JP4845066B1 - Method and apparatus for detecting state of power storage device - Google Patents

Abstract

A state detection method and apparatus for an electricity storage device capable of determining whether an appropriate discharge capacity is maintained regardless of whether charging / discharging is stopped or not are stopped.
In step S7, a voltage change amount ΔVa_n is calculated from a voltage V_end when charging / discharging is stopped and a current voltage V_now stored in a storage unit 120. In step S9, the discharge capacity correction function F (SOH_n1, x) corresponding to the deterioration degree SOH_n1 read in step S8 is read from the storage unit 120, and in step S10, ΔVa_n is substituted for the variable x to calculate the discharge capacity correction amount COD_SOH_n. To do. In step S11, the current discharge capacity COD_now is calculated from the current voltage V_now and the discharge capacity correction amount COD_SOH_n calculated in step S10.
[Selection] Figure 1

Description

  The present invention relates to a state detection method and apparatus for a power storage device, and more particularly to a state detection method and apparatus related to the discharge capability of a power storage device.

  In recent years, there has been an increasing need for power storage devices. For example, automobiles are equipped with many electrical devices that operate by receiving power supply from a storage battery, which is a power storage device, and the importance of storage batteries is increasing. In recent years, by-wire has progressed, and safety-related parts represented by electric brakes (EPB) have been electrically controlled. In addition, along with energy saving and carbon dioxide emission regulations, it is required to secure an idling stop function and a restart capability at a short stop at an intersection or the like.

  In fields other than automobiles, for example, in order to promote the use of natural energy such as solar power generation and wind power generation, power storage devices are used for leveling generated power and storing surplus power. Furthermore, the power storage device is also used as a backup power source such as a stabilized power source and an auxiliary power source for supplying power to an electric device during a power failure. As such an electricity storage device, a device that accompanies movement of an electrolyte such as a secondary battery or a capacitor is used.

  In general, under the condition that the electricity storage device is sufficiently stable after the charge / discharge stop, there is a 1: between the open-circuit voltage (OCV) and the remaining capacity (SOC: State of charge) as indicated by reference numeral 81 in FIG. There is a relationship corresponding to 1. However, such a 1: 1 relationship is obtained under stable conditions such as in a laboratory. For example, in the case of a storage battery containing an electrolytic solution, the storage device after charging / discharging has the respective effects of ion generation / extinction reaction on the electrode plate surface due to electrochemical reaction, and ion movement due to diffusion or convection of the electrolytic solution, etc. Is receiving.

  Such an effect always occurs in an electricity storage device in which ions move in an electrolyte solution such as a Li ion battery or a lead storage battery. Even in the case of a capacitor, when an electrolytic solution is used as a power storage medium, the concentration of the medium changes, so that it is also affected by ion diffusion and the like. Even when a solid electrolyte is used as a medium instead of the electrolytic solution, ions in the electrolyte are biased due to a power storage action. For this reason, it takes time to reach a stable state depending on the medium or medium, and a convergence time corresponding to the characteristics of each power storage device is required until a stable OCV is obtained (for example, a liquid lead acid battery In the case of about 20 hours).

  As described above, when the ion concentration in the electrolyte or electrolyte changes transiently, it takes a long time until the ion concentration becomes sufficiently homogeneous. As a result of measuring the battery voltage, a 1: 1 relationship is not established between the OCV and the SOC. 36 and 37 are diagrams illustrating an example of a transient change in OCV when the SOC and temperature of the storage battery are constant. FIG. 36 shows that even if the SOC is constant, it takes time for the OCV (reference numeral 82) to stabilize at a constant value. In addition, FIG. 37 shows changes in the OCV (reference numerals 83, 84, 85) in the storage battery when the SOH (degradation level, state of health) is different. Even when the discharge conditions are the same, it does not converge to the same OCV if the SOH is different.

  Thus, in order to obtain the SOC from the OCV with high accuracy, it is necessary to use an SOC that appropriately reflects the SOH of the electricity storage device. In addition, transient changes after stopping charging / discharging include those with short reaction times such as ion formation / annihilation reactions, and those with long reaction times such as electrolyte diffusion and convection. ing. Such transient changes with different reaction times also differ depending on the SOC and SOH.

  To make it possible to use the electricity storage device stably, if its state detection is performed with high accuracy and there is a risk of insufficient discharge capacity, it will be detected early so that it can be dealt with. There is a need. In a system using an electricity storage device, a lower limit voltage (a limit point of discharge capacity) of the electricity storage device that is required to be maintained even during charging / discharging is set in order to properly operate electric devices in the system. . Therefore, in the state detection of the power storage device, it is important to accurately determine whether the voltage of the power storage device is higher than the lower limit voltage as the determination of the discharge capability ((COD: Capability of Discharge)).

  The COD of the electricity storage device is determined by whether or not the voltage of the electricity storage device can always be maintained higher than the lower limit voltage for any load. An example of the voltage change of the electrical storage device at the time of discharge is shown in FIG. FIG. 38 schematically shows the change over time of the battery voltage 33 when a load is connected to the storage battery and discharged. The battery voltage 33 at the time of discharge decreases with time. However, when the lower limit voltage required for the system, that is, the limit point of the discharge capacity, is reached, it becomes impossible to supply appropriate electric power to the electrical equipment of the system.

The amount of voltage drop from the initial battery voltage 31 can be expressed as the following equation.
Voltage drop = reaction resistance (increase) x current + internal potential (decrease)
Here, the voltage drop due to the reaction resistance (arrow D) is associated with the energy required to cause the electrochemical reaction, and changes due to deterioration (SOH) of the electricity storage device. The internal potential drop (arrow C) is due to a change in the active material due to the electrochemical reaction, and changes depending on the remaining capacity (SOC) of the electricity storage device. From FIG. 38, even if the internal potential 34 is higher than the lower limit voltage 35, if the decrease due to the discharge reaction resistance is large, the limit point of the discharge capacity is reached. As described above, in an electricity storage device with an electrochemical reaction, the discharge capacity COD is determined by the internal potential C of the storage battery, the discharge reaction resistance D, and the lower limit voltage 35 defined by the system specifications. For this purpose, it is necessary to separately determine the discharge reaction resistance D (deterioration) and the internal potential C (remaining capacity).

  As a method for determining the discharge capability of the power storage device, a method is conceivable in which the remaining capacity is directly measured and determined by completely resting the power storage device after the system is stopped and then fully charging again. However, in this method, the power storage device becomes unusable due to the remaining capacity measurement, and there is a possibility that the original function cannot be realized particularly in a system in which the power storage device is used for backup. Moreover, since it takes a considerable amount of time for both discharging time and charging time to discharge and measure the entire capacity, the operating efficiency of the system is greatly reduced.

  As a method for determining a deterioration state of an electricity storage device, a method is known in which an internal state is estimated by an impedance method and a discharge capacity is estimated based on the information. However, this method can be applied when the power storage device is used at or near a full charge, but cannot be applied when the power storage device is operated in a partial state of charge (PSOC). In recent years, power storage devices have come to be used for natural energy leveling applications. In such applications, power storage devices are operated in a partially charged state in which the remaining capacity differs greatly from full charge.

  The difference in operation method between when the power storage device is operated at full charge and when it is operated at PSOC will be described with reference to FIG. FIG. 4A shows state detection in the conventional operation method, and FIG. 4B shows state detection in the PSOC operation method. In the conventional operation method, it is required to detect the decrease 42a of the deterioration margin 42 due to deterioration and determine the remaining deterioration margin 42b. On the other hand, in the PSOC operation method, the decrease 44a, 45a of the charging area 44 and the deterioration margin 45 due to deterioration is detected, and the range of the operation area 43 is set in order to secure necessary charging capacity and discharging capacity. It is necessary to perform control such as changing and newly providing a charging area 44b and a deterioration margin 45b.

  In the conventional method of operating a power storage device that is always used in a fully charged state, it is considered that the impedance of the power storage device changes due to only the influence of deterioration. Therefore, the degree of deterioration (SOH) of the electricity storage device can be known by measuring the impedance. On the other hand, in the operation by PSOC, since the impedance is affected by both the deterioration and the remaining capacity, the degree of deterioration cannot be obtained from the impedance.

  In the electric storage device, it has been described above that transient changes with different reaction times occur after charging and discharging. However, in order to reflect such differences in reaction times, for example, in Patent Document 1, transient changes are made up of three time constants. A method for evaluating the components separately is described. Here, the transient response changes according to the charge / discharge time, and there is a mention of the resistance component, the polarization component according to the internal reaction of the battery, and the diffusion rate of the electrolytic solution.

Japanese Patent Laid-Open No. 2005-106615

  However, a method for accurately detecting the state of the electricity storage device during charging / discharging during system operation has not been known. As supplementary means for determining the remaining capacity during system operation, there is a method of estimating the current remaining capacity based on the integrated current value at the time of charging / discharging of the power storage device, and determining the discharge capacity using this. However, only the integrated values of the charging current and the discharging current cannot reflect the decrease in charging / discharging efficiency accompanying the change in the internal state quantity such as the deterioration of the storage device, and the storage device calculated from the integrated current value cannot be reflected. There may be a difference between the remaining capacity and the remaining capacity of the power storage device that can actually be used, and the discharge capacity may not be accurately calculated. In addition, it is not possible to determine the discharge capability, such as whether or not the voltage of the power storage device can be maintained higher than the voltage required by the system simply by monitoring the remaining capacity.

  An example in which the voltage of the power storage device is different even when the current integrated value is the same will be described below with reference to FIG. In the figure, the voltage at the end of charging when charging / discharging at which the current integrated value is the same between charging and discharging is displayed with the horizontal axis as the number of repeated cycles. The accumulated charge amount and the accumulated discharge amount in one cycle are both 5% (ΔSOC = 5%), and the accumulated charge / discharge amount in each cycle is set to 0. In FIG. 40, the remaining capacity (SOC) at the start of charging / discharging of the electricity storage device is 90% (reference numeral 51 to 53), 80% (reference numeral 54), 70% (reference numeral 55 to 60), 60% (reference numeral 61). Shows the case.

  FIG. 40 shows that the voltage at the end of charging increases as the number of charge / discharge cycles increases. This indicates that the state quantity inside the electricity storage device changes as the charge / discharge cycle is repeated. Further, even when the change amount of the current integrated value is 0, the state amount of the electricity storage device is changing. The data shown in FIG. 40 is experimental data obtained using a Furukawa Battery liquid lead storage battery (JIS standard 55D23).

  On the other hand, in the state detection after stopping charging / discharging, transient changes with different reaction times occur inside the electricity storage device. unknown. Even when the state detection is performed by dividing the transient change after stopping charging / discharging into components having different time constants as in the state detection method described in Patent Document 1, if the SOC or SOH of the electricity storage device changes, each time constant also changes. Although it is necessary to adjust according to it, there existed a problem that it was difficult to obtain | require the time constant with respect to different SOC and SOH with high precision, and it became difficult to detect the state of a storage battery with high precision.

  Therefore, the present invention has been made to solve these problems, and it is possible to determine whether appropriate discharge capacity is maintained regardless of whether charging / discharging is stopped or not. An object of the present invention is to provide a device state detection method and apparatus.

1st aspect of the state detection method of the electrical storage device of this invention is a state detection method of the electrical storage device which determines the discharge capability during charging / discharging and charging / discharging stop for every predetermined | prescribed period, Comprising: The last charging / discharging stop The measured voltage value of the electricity storage device measured immediately after is stored in a predetermined storage unit as a charge / discharge stop voltage V_end, the charge / discharge stop voltage V_end is read from the storage unit, and the charge / discharge stop voltage The current voltage change value ΔVa_n is calculated by subtracting the current voltage measurement value V_now (assuming the number of cycles is n) from V_end, and the discharge capacity created in advance from the deterioration degree SOH of the electricity storage device and the voltage change amount ΔVa_n. The correction function F (SOH, ΔVa_n) is used to calculate the discharge capacity correction amount COD_SOH_n of the power storage device, and the current discharge capacity COD_now of the power storage device is expressed by the following equation: COD_now = V_now−C D_SOH_n
And when the discharge capability COD_now is greater than a predetermined threshold value COD_Th, it is determined that the discharge capability of the power storage device is maintained.

  In another aspect of the method for detecting a state of an electricity storage device according to the present invention, the deterioration degree SOH is a deterioration degree SOH_n1 calculated when the number of cycles n1 (n1 ≦ n) during the charge / discharge stop closest to the present time, The discharge capacity correction amount COD_SOH_n reads the discharge capacity correction function F (SOH_n1, x) (x is a variable) corresponding to the deterioration degree SOH_n1 from the storage unit, and substitutes the voltage change amount ΔVa_n for the variable x. It is characterized by being calculated.

  In another aspect of the state detection method for an electricity storage device of the present invention, the discharge capacity correction function F (SOH, ΔVa) is 2 or more (m Of the relaxation function fi (i = 1 to m) for each reaction rate, and the voltage measurement value is stored in the storage unit while charging and discharging of the electricity storage device is stopped, The relaxation function fi is optimized using the voltage measurement value stored in the storage unit according to the elapsed time from the charge / discharge stop.

In another aspect of the state detection method of the electricity storage device of the present invention, when the electricity storage device is in a charge / discharge stop and the elapsed time from the charge / discharge stop exceeds a predetermined time (first relaxation time),
The relaxation function fi for each reaction rate corresponding to a fast transient change is optimized using the voltage measurement value stored in the storage unit, and the fast transition change is made using the optimized relaxation function for each reaction rate fi. A dependent deterioration degree SOH_fast_n is calculated, and a predetermined degree is calculated from the deterioration degree SOH_slow_n2 and the deterioration degree SOH_fast_n depending on the slow transient change calculated when the number of cycles n2 (n2 ≦ n) closest to the current charge / discharge is stopped. Using the function G, the current deterioration degree SOH_n is expressed by the following equation: SOH_n = G (SOH_fast_n, SOH_slow_n2)
The discharge capacity correction amount COD_SOH_n is obtained by reading the discharge capacity correction function F (SOH_n, x) corresponding to the deterioration degree SOH_n from the storage unit and substituting the voltage change amount ΔVa_n into the variable x. It is calculated.

In another aspect of the state detection method for an electricity storage device of the present invention, the electricity storage device is in a charge / discharge stop and the elapsed time from the charge / discharge stop exceeds a predetermined second relaxation time longer than the first relaxation time. Further, the relaxation function fi for each reaction rate depending on a slow transient change is optimized using the measured voltage value stored in the storage unit, and the optimized relaxation function for each reaction rate fi is used. A degradation degree SOH_slow_n that depends on a slow transient change is calculated, and the current degradation degree SOH_n is calculated using the function G from the calculated degradation degree SOH_fast_n that depends on the fast transient change and the degradation degree SOH_slow_n that depends on the slow transient change. Is represented by the following formula: SOH_n = G (SOH_fast_n, SOH_slow_n)
It is characterized by calculating.

  According to another aspect of the state detection method of the power storage device of the present invention, the voltage measurement is performed immediately after the charge before the state detection is completed by charging the power storage device with a predetermined capacity immediately after the charge / discharge stop (charging before the state detection). A value is stored in the storage unit as the charge / discharge stop voltage V_end.

A first aspect of the state detection device for an electricity storage device according to the present invention is a state detection device for an electricity storage device that determines the discharge capability during charge / discharge and during charge / discharge stop for each predetermined cycle, and the voltage of the electricity storage device A storage unit that stores measurement values, a state detection unit that reads data stored in the storage unit and determines the discharge capability of the power storage device for each cycle, and inputs determination results from the state detection unit State output means for outputting to the outside, and the storage unit stores the voltage measurement value of the electricity storage device measured immediately after the last charge / discharge stop as a charge / discharge stop voltage V_end, and the state detection unit Reads the charge / discharge stop voltage V_end from the storage unit, and subtracts the current voltage measurement value V_now (assuming the number of cycles is n) from the charge / discharge stop voltage V_end to calculate the current voltage change amount ΔVa_n. The discharge capacity correction amount COD_SOH_n of the power storage device is calculated using a discharge capacity correction function F (SOH, ΔVa_n) created in advance from the degree of deterioration SOH of the power storage device and the voltage change amount ΔVa_n. The current discharge capacity COD_now is expressed by the following equation: COD_now = V_now−COD_SOH_n
And when the discharge capability COD_now is greater than a predetermined threshold value COD_Th, it is determined that the discharge capability of the power storage device is maintained.

  According to the present invention, it is possible to provide an electrical storage device state detection method and apparatus capable of determining whether an appropriate discharge capacity is maintained regardless of whether charging / discharging is stopped or not. It becomes possible.

It is a flowchart for demonstrating the flow of a process of the state detection method of the electrical storage device of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the state detection apparatus of the electrical storage device of 1st Embodiment. It is a flowchart for demonstrating the flow of a process of the state detection method of the electrical storage device of the 2nd Embodiment of this invention. It is a graph which shows the relationship at the time of discharge of the electrical storage device at the time of stability, and SOH. It is a graph which shows the transient change of OCV after stopping a 1st discharge. It is a graph which shows a time-dependent change of the amount of voltage drops when performing 2nd discharge at the time of different elapsed time after the 1st discharge stop. It is a graph which shows the time change of OCV and OCV change amount after charge stop. It is a flowchart for demonstrating the flow of a process of the state detection method of the electrical storage device of the 3rd Embodiment of this invention. It is a flowchart for demonstrating the flow of a process of the state detection method of the electrical storage device of the 4th Embodiment of this invention. It is a flowchart explaining the state detection method of a 1st reference example. It is a block diagram which shows schematic structure of the state detection apparatus using the state detection method of a 1st reference example. It is a flowchart which determines the timing which performs the data measurement required for a state detection. It is a flowchart explaining the method to determine charging / discharging stop. It is a flowchart explaining the selection method of OCV _20hr . It is a flowchart explaining the method of optimizing F (t). It is a flowchart explaining the method of optimizing F (t). It is a flowchart explaining the method of calculating state quantity SOH and SOC. It is a graph which shows an example of a relaxation function and a relaxation function for every reaction rate. It is a graph which shows an example of the relaxation function for every reaction rate, and its ratio. It is a graph which shows an example of a stable OCV estimation formula. It is a flowchart explaining the state detection method of a 2nd reference example. It is a graph which shows an example of charging efficiency (eta) 1 and (eta) 2. It is a flowchart explaining the state detection method of a 3rd reference example. It is a graph which shows an example of the change of the relaxation function for every reaction rate. It is a graph which shows an example of the change of SOH with respect to a quick reaction rate. It is a graph which shows an example of the correction coefficient with respect to SOH. It is a flowchart explaining the determination method of the state quantity in a 3rd reference example. It is a schematic diagram for stratification of an electrical storage device. It is a flowchart explaining the outline of the state detection method of the electrical storage device which concerns on a 4th reference example. It is a block diagram of the state detection apparatus of the electrical storage device which concerns on a 4th reference example. It is a graph which shows the change of the electric current by the charge / discharge in driving | operation, and charge before state detection, and a voltage. It is a flowchart explaining the process after charge before a state detection is complete | finished after a state detection mode is requested | required. It is a flowchart explaining a process when state detection mode is materialized. It is a flowchart explaining the outline of the state detection method of the electrical storage device which concerns on other embodiment of this invention. It is a graph which shows the relationship between a stable open end voltage and SOC. It is a graph which shows the change of OCV when SOC is constant. It is a graph which shows the change of OCV when SOH differs. It is a figure which shows typically the time change of the battery voltage when connecting a load to a storage battery and making it discharge. It is explanatory drawing explaining the difference in the operation system when operating an electrical storage device by a full charge, and operating by PSOC. It is a graph which shows the voltage at the time of completion | finish of charging / discharging when charging and discharging with the same integrated current value are repeated.

  A power storage device state detection method and apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description. Hereinafter, the state detection method and state detection device of the power storage device of the present invention will be described by taking a storage battery such as a liquid lead storage battery mounted on a vehicle as the power storage device as an example. However, the contents described below are not limited to in-vehicle storage batteries, but can be similarly applied to power storage devices used for solar power generation, wind power generation, and the like, and power storage devices used for backup power sources such as a stabilized power source and an auxiliary power source. Is.

  The method and apparatus for detecting the state of an electricity storage device according to the present invention enables determination of the discharge capability of the electricity storage device regardless of whether the electricity storage device is being charged / discharged or stopped. First, the basic processing contents related to the method for detecting the state of the electricity storage device of the present invention will be described in the case of state detection when transient change after charge / discharge stop is mitigated (hereinafter referred to as mitigation state detection). Explain to the subject. Hereinafter, the voltage when the power storage device stops charging / discharging and reaches a state satisfying a predetermined stability condition is defined as a stable voltage at stop, and voltage measurement when time t has elapsed since the power storage device stopped charging / discharging. The amount of change from the stable voltage when the value is stopped is defined as the amount of change in the voltage when stopped.

  A relaxation function F (t) that depends on a predetermined state quantity of the power storage device is created and used in advance as a function for calculating the above-described stop voltage change amount. Then, the relaxation function F (t) is optimized using the amount of change in the stop voltage obtained from the voltage measurement value, and the state detection is performed by estimating a predetermined state quantity from the optimized relaxation function F (t). In the method for detecting the state of the electricity storage device of the present invention, the discharge capability (COD) is estimated using the relaxation function F (t), and the estimated COD is compared with a preset threshold value. It is determined whether the discharge capacity is properly maintained.

  In the present invention, as the COD used for the determination of the discharge capacity, the battery voltage when the electricity storage device is stable is estimated using the relaxation function F (t). In addition, when the estimated COD is larger than this threshold, a voltage value set so that the battery voltage does not become lower than the lower limit voltage required by the system is used even when charging / discharging from that state. This threshold value is set so that the battery voltage does not fall below the system-required lower limit voltage due to at least the amount of voltage fluctuation due to normal charging / discharging. In addition, examples of state quantities that can be estimated from the relaxation function F (t) include SOH (State of health), which is an indicator of the degree of deterioration of the power storage device, and SOC indicating the remaining capacity.

  There are transient changes in electricity storage devices after charge / discharge stoppages, from those with fast reaction speeds, such as ion generation / annihilation reactions, to those with slow reaction speeds, such as electrolyte migration. It affects the change in the state quantity. Therefore, in the state detection method for an electricity storage device of the present invention, a change in state quantity for each reaction rate is estimated using the relaxation function F (t), and these are integrated to determine the state quantity.

  As the stable voltage at the time of stop, the open-circuit voltage of the electricity storage device (hereinafter referred to as OCV at the time of stability) when a sufficient time has elapsed after stopping charging / discharging can be used. The open end voltage OCV is a voltage between terminals when the terminal of the electricity storage device is opened and the discharge is stopped. The stable voltage at the time of stop used in the method for detecting the state of the electricity storage device of the present invention is not limited to the stable OCV, and when the transient influence on the electricity storage device is limited, the stable voltage at that time can be used. . As an example, a minute current (dark current) may be supplied to the load control device while the power supply from the power storage device to the load is stopped. Even when the load is stopped, the voltage when a sufficient time elapses after the load is stopped can be set as the stable voltage at the time of stop.

  In addition, even when the charge / discharge amount from the electricity storage device is always a constant value, the transient effect on the electricity storage device is considered to be sufficiently small, so the voltage when sufficient time has elapsed since the load was stopped. Can be a stable voltage when stopped. In this way, when the current due to charging / discharging is small or constant and the influence on the transient change inside the electricity storage device is limited within a predetermined range, when the power supply to the load is stopped, In addition to determining that the discharge has stopped, the voltage when a long time has elapsed after stopping the charge / discharge in a state where a minute current or a constant current is continued can be set as a stable voltage at the time of stop. In this case, it is preferable that a voltage correction amount for correcting a voltage change due to a minute current or a constant current is determined in advance, and the voltage measurement value is corrected using this.

The following description will be made using a stable OCV as an example of a stable voltage at a stop. When the OCV at the time of stability is used, the state quantity SOC can be expressed by the following equation using the relationship shown in FIG.
SOC = FS (OCVs ′ (SOC ′, SOH, T)) (1)
OCV _s (SOC, SOH, T) = lim (V _mes (t)) (2)
Here, OCV _s is a stable OCV calculated this time, OCV ′ is a previously calculated OCV stable time, t is an elapsed time since charge / discharge stop, SOC ′ is a remaining capacity calculated last time, and V _mes (t) is an elapsed time. The measured voltage value at t and T represents the temperature of the electricity storage device. Lim in the equation (2) indicates that the elapsed time t from the charge / discharge stop is infinite, and the right side of the equation (2) indicates the power storage when the elapsed time t after the charge / discharge stop is infinite. The device voltage measurement V _mes (t) is shown. Even when a stop stable voltage other than the stable OCV is used, a relational expression similar to the above can be created and used in advance with the SOC.

  In the above equation, the SOC is determined depending on the previously calculated OCVs ′, and at the same time, the OCVs also depends on the SOC, and further changes depending on the state quantity SOH and the temperature T of the power storage device. It shows that Further, since OCVs depends on the state quantity SOH, the state quantity SOC also depends on SOH, and it is necessary to perform each update at an appropriate timing.

OCV _s is V _mes (t) when the elapsed time t from charge / discharge stop is infinite as shown in the equation (2), but in practice, when the change of V _mes (t) becomes sufficiently small. It can be V _mes (t) at the time of a possible elapsed time t. Further, when the electricity storage device is a liquid lead-acid battery, OCV _s is V _mes (t) when the amount of change in OCV per hour is 5 mV or less, or when 20 hours have elapsed since charging / discharging was stopped. It can be. In the following _description , V _mes (t) when 20 hours have elapsed from the stop of charging / discharging of the storage battery is defined as OCV _20hr of the following formula, and this is used for OCV _s .
OCV _20hr = V _mes (t = 20hr)
OCV _s (SOC, SOH, T) ≒ OCV _20hr (3)

When the amount of change from the stable OCV of the voltage measurement value V _mes (t) after charge / discharge stop, that is, the OCV change amount (voltage change amount at stop) is ΔV (t),
_{ΔV (t) = V mes (} t) -OCV 20hr (4)
It can be expressed as. This OCV change amount ΔV (t) has been treated including all transient changes using the term “polarization” in the conventional definition of electrochemistry. However, since ΔV (t) is a voltage change caused by a relaxation process until it approaches the stable OCV, it is affected by the following voltage change factors.

  Factors of voltage change include the electrode plate state, the ion concentration in the vicinity of the electrode plate, their solid-phase reaction, solid-liquid reaction, and precipitation and convection of the electrolyte, and ion movement accompanying diffusion. The OCV variation ΔV (t) is considered to be caused by a combination of relaxation processes having different reaction rates. Thus, since the transient change after stopping charging / discharging of the electricity storage device includes reaction processes with different speeds, in order to accurately determine the discharging capability of the electricity storage device after stopping charging / discharging, It is preferable to detect the state using a method for evaluating the state change.

The OCV variation ΔV (t) is expressed by the following equation using a function F (t) composed of m polynomials according to the difference in reaction rate.
ΔV (t) = F (t)
= F ₁ (t) + f ₂ (t) +... F _m (t) = Σf _i (t) (5)
In the above relaxation function F (t), each term f _i (t) indicates the contribution to the voltage change for each relaxation process having a different reaction rate of the electricity storage device. Hereinafter, the relaxation function for each reaction rate f _i ( t). Each f _i (t) is a function that depends on the deterioration degree SOH, the remaining capacity SOC, and the temperature T, which are state quantities of the power storage device. The relaxation function f _i (t) for each reaction rate in the equation (5) is optimized by using the OCV change amount ΔV (t) calculated from the voltage measurement value V _mes (t) after the charge / discharge stop. Can be determined.

In the state detection device using the state detection method of the present invention, the initial values SOC ⁰ , SOH _i ⁰ , and OCV _20hr ⁰ of SOC, SOH, and OCV _20hr before the state detection is started are _stored in the state detection device. Using the respective reference values SOC ^{ref (0)} , SOH _i ^{ref (0)} , and OCV _20hr ^{ref (0)} stored in advance, the following settings can be made.
SOC ⁰ = SOC ^{ref (0)}
SOH _i ⁰ = SOH _i ^{ref (0)}
OCV _20hr ⁰ = OCV _20hr ^{ref (0)}

The relaxation function F of the equation (5) representing the OCV change amount ΔV (t) after the nth (n is an integer of 1 or more) charge / discharge stop after the state detection device starts the state detection of the power storage device. When (t) and the relaxation function f _i (t) for each reaction rate are F ⁿ (t) and f _i ⁿ (t), respectively, the SOC and the SOH corresponding to the i-th reaction rate (SOC ⁿ , SOH respectively) _i ⁿ ), the relaxation function fi _n (t) for each reaction rate is expressed by the following equation.
f _in (t) = f _i ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * g (T) (6)
^{_{Here, f i ref (t),}} SOC ref, SOH i ref is, f _i (t) in the predetermined initial state (e.g. unused state), SOC, a SOH _i, g (T) is It is a function representing temperature dependence.

In the equation (6), when the temperature T and the SOC are constant regardless of time, SOH _i ⁿ is calculated as follows: SOH _i ⁿ = {f _i ⁿ (t) / f _i ^ref (t)} * SOH _i ^ref (7 )
It can be calculated from Therefore, it optimizes the f _i ⁿ (t) of formula (5) to the [Delta] V (t) that is calculated from the voltage measured value V _mes (t), calculates the SOH _i ⁿ from equation (7) using the same Can do.

When SOH _i ⁿ for each transient response having a different reaction rate is calculated from the equation (7), the total SOH ⁿ calculated by integrating these is obtained by using a predetermined function G: SOH ⁿ = G (SOH ₁ ⁿ , SOH ₂ ⁿ ,..., SOH _m ⁿ ) (8)
It can be expressed as For example, if m coefficients are A to M for m SOH _i ,
SOH ⁿ = A * SOH ₁ ⁿ + B * SOH ₂ ⁿ +... + M * SOH _m ⁿ
= A * {f ₁ ⁿ (t) / f ₁ ^ref (t)} SOH ₁ ^ref +
B * {f ₂ ⁿ (t) / f ₂ ^ref (t)} SOH ₂ ^ref +... +
M * {f _m ⁿ (t) / f _m ^ref (t)} SOH _m ^ref (8-1)
It can be expressed as. However, Formula (8-1) is an example showing the relational expression of Formula (8), and is not limited to this. Using the SOH ⁿ calculated as described above, it is possible to detect the deterioration state of the power storage device. Similarly, SOC ⁿ which is another state quantity can be calculated using the optimized relaxation function F (t).

Using SOH _i ⁿ calculated by Equation (7) Update the f _i ⁿ (t) by the following equation, using this to calculate the SOC _i ^n.
f _i ⁿ (t) = f _i ^ref (t) * {SOC _i ⁿ⁻¹ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * g (T) (6-1)

From Expression (4) and Expression (6-1), OCV _20hr can be calculated by the following expression.
OCV _{20 hr} = V _mes (t) −Σ [f _i ^ref (t) * {SOC ⁿ⁻¹ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref }] * g (T) (9)
By substituting this OCV _{20 hr} into (Equation 1), SOC ⁿ can be calculated and used for SOC state detection.

As described above, m reference values f _i ^ref (t) (i = 1 to m) corresponding to m kinds of reaction rates and m deterioration values reference values SOH _i ^ref (i = 1 to m). And m relaxation rate functions f _i ⁿ (t) (i = ^{1 to} m) after the nth charge / discharge stop based on the reference value SOC ^ref of one remaining capacity. Can do. As a result, it is possible to detect OCV, SOC, and SOH reflecting the degree of deterioration corresponding to different reaction rates and to perform highly accurate state detection.

  In the above, the basic processing content related to the state detection method has been described for the state detection at the time of relaxation after the charge / discharge stop, but the state detection method of the power storage device of the present invention is limited to the state detection at the time of relaxation. However, it is possible to detect the state of the electricity storage device even during charging / discharging. Hereinafter, the state detection when the system is in operation and the power storage device is charging / discharging is referred to as state detection during charging / discharging. In the above description, since only the state detection at the time of relaxation is targeted, the number n of state detection cycles is the number of charge / discharge stops. However, in the state detection including the state detection at the time of charge / discharge, the cycle number n is set to a predetermined time interval, for example. It is good to set the number of cycles when the state detection is performed periodically.

  In the relaxation state detection, the OCV converges to the stable OCV with the elapsed time t from the stop of charging / discharging (the OCV change amount ΔV (t) converges to 0). Therefore, the relaxation function can be simply expressed as a function F (t) of the elapsed time t. However, the discharge capability COD of the electricity storage device during charge / discharge is strongly affected by the amount of voltage change from the voltage at the time of charge / discharge stop when the elapsed time from the latest charge / discharge stop is short, and deteriorates when the elapsed time becomes long Highly affected by SOH.

  Accordingly, the function F used as the relaxation function in the relaxation state detection after the charge / discharge stop is hereinafter referred to as a discharge capacity correction function F as a function used in both the relaxation state detection and the charge / discharge state detection. Further, ΔVa (t) is used to distinguish the amount of voltage change from the voltage at the time of stopping charging / discharging from the amount of change ΔV (t) in equation (4). At this time, the discharge capacity correction function F is expressed as F (SOH, ΔVa) as a function of the voltage change amount ΔVa (t) and the deterioration degree SOH. Here, the dependency on the elapsed time t is included in the time dependency of the voltage change amount ΔVa (t).

The voltage at the latest charge / discharge stop, that is, the voltage at the last charge / discharge stop when viewed from the state detection time (current) is defined as the charge / discharge stop voltage, and this is expressed as V_end. Further, when the elapsed time from the last charge / discharge stop to the state detection time point (current) is t and the current voltage is V_now, the voltage change amount ΔVa (t) is ΔVa (t) = V_end−V_now (10)
Is calculated by Here, the charging / discharging stop voltage V_end is V_cha_end when charging is stopped, and V_dis_end when discharging.

The relationship between the OCV change amount ΔV (t) and the voltage change amount ΔVa (t) while charging and discharging are stopped will be described below. Since V _mes (t) in the equation (4) is V_now here, the calculation formula for the OCV variation ΔV (t) shown in the equation (4) can be rewritten as the following equation.
ΔV (t) = V_now-OCV 20hr (4-1)
= F (SOH, ΔVa)
Equation (10) and equation (4-1) than, between the voltage change amount .DELTA.Va (t) and the OCV variation ΔV (t) ΔVa (t) + ΔV (t) = V_end-OCV 20hr (11)
There is a relationship.

Since the discharge capacity (COD_now) during the charge / discharge stop is equal to the OCV when stabilized, that is, OCV _{20 hr} , from the equation (4-1),
_{COD_now = OCV 20hr = V_now-ΔV} (t)
= V_now-F (SOH, ΔVa) (12)
Given in. That is, the discharge capacity COD_now is a value obtained by subtracting the discharge capacity correction amount, that is, the value of the discharge capacity correction function F (SOH, ΔVa) from the current voltage V_now.

Similarly to the charging / discharging stop, the discharging capability COD_now during charging / discharging can also be calculated using the equation (12). When the discharge capacity correction amount, which is the value of the discharge capacity correction function F (SOH, ΔVa), is expressed as COD_SOH, the state detection method for the storage device of the present invention performs both the state detection during charge / discharge and the state detection during relaxation. The discharge capacity COD_now can be calculated by the following equation.
ΔVa (t) = V_end−V_now
COD_SOH = F (SOH, ΔVa)
COD_now = V_now-COD_SOH
When the discharge capacity COD_now calculated by the above equation is larger than the threshold value COD_Th, it is determined that the discharge capacity is maintained, and when it is less than the threshold value COD_Th, it is determined that the discharge capacity is insufficient.

(First embodiment)
A power storage device state detection method and apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart for explaining the flow of processing of the state detection method for an electricity storage device according to the present embodiment, and FIG. 2 is a block diagram showing the configuration of the state detection device for the electricity storage device according to the present embodiment.

  The state detection apparatus 100 of this embodiment shown in FIG. 2 detects the state of the electricity storage device (storage battery) 10 mounted on the vehicle 1 of the target system. The vehicle 1 includes a charging unit (alternator) 11 for charging the storage battery 10 during engine operation, and a control unit 12 for controlling charging by the charging unit 11. In addition, a load 2 of various electrical components is mounted on the vehicle 1 and is connected to a storage battery 10 to receive power. The storage battery 10 is provided with a voltage measuring means 20, a current measuring means 21, and a temperature measuring means 22, and the state detection device 100 inputs each measurement value and performs state detection.

  The state detection device 100 includes a state detection unit 110, a storage unit 120, and a state output unit 130. The state detection unit 110 inputs the voltage measurement value, the current measurement value, and the temperature measurement value of the storage battery 10 from the voltage measurement unit 20, the current measurement unit 21, and the temperature measurement unit 22, respectively, and performs processing by the state detection method of the present embodiment. The state of the storage battery 10 is detected. The storage unit 120 stores various reference data and measurement data necessary for the state detection process. Furthermore, the state output means 130 is means for notifying a driver or the like of a state detection result or the like.

  The state detection method of the power storage device of the present embodiment is periodically executed at predetermined time intervals in the state detection unit 110 after the state detection device 100 is activated, regardless of whether the storage battery 10 is being charged or discharged. In FIG. 1, when the n-th state detection is started in step S1, the voltage measurement value of the storage battery 10 is acquired using the voltage measuring means 20 in step S2, and this is set as the current voltage V_now.

  In step S3, it is determined whether the storage battery 10 is charging / discharging (determination result is YES) or charging / discharging is stopped (determination result is NO). If the determination result is YES, the process proceeds to step S8, and the determination result is NO. In step S4, the process proceeds to step S4. In this determination, a current measurement value of the storage battery 10 is acquired using the current measurement means 21, and when the value is 0, it is determined that charging / discharging is stopped, and when it is not 0, charging / discharging is determined. Alternatively, it may be determined that charging / discharging is stopped when the absolute value of the current measurement value is equal to or less than a predetermined current threshold, and that charging / discharging is determined otherwise.

  If it is determined in step S3 that charging / discharging is stopped (determination result is NO), it is next determined in step S4 whether the storage battery 10 is immediately after stopping charging / discharging. If the determination result is YES, the process proceeds to step S5. If NO, the process proceeds to step S7. This determination can be made immediately after stopping charging / discharging when it is determined that charging / discharging is being performed in the previous (n-1th) state detection. If it is determined in step S4 that it is immediately after the charge / discharge stop (the determination result is YES), the current voltage V_now is changed to the voltage V_end at the time of charge / discharge stop (V_cha_end at the time of charge stop, V_dis_end at the time of stop of discharge) in step S5. After setting and storing this in the storage unit 120, the process proceeds to step S7.

In step S7, the voltage V_end at the time of the charge / discharge stop preserve | saved at the memory | storage part 120 is read. This voltage V_end when charging / discharging is stopped is stored in the storage unit 120 in step S5 when charging / discharging stops closest to the present time. A voltage change amount ΔVa_n is calculated from the voltage V_end at the time of stopping charging / discharging and the current voltage V_now using the following equation.
ΔVa_n = V_end−V_now

  In step S8, the deterioration degree SOH_n1 stored in the storage unit 120 is read. Here, n1 indicates the number of cycles when the SOH is last updated (n1 ≦ n), and the deterioration degree SOH_n1 is the last SOH updated last time. As the initial value SOH_0 of SOH_n, the characteristic value of the new storage battery 10 is stored in advance in the storage unit 120 as reference data, and the SOH is read from the reference data and used. Alternatively, a characteristic value of a general power storage device is stored in advance in the storage unit 120 as reference data, and the SOH of this reference data is set to SOH_0. This SOH_0 is rewritten with SOH_1 calculated at the time of initial state detection after the storage battery 10 is mounted. In step S9, the discharge capability correction function F (SOH_n1, x) corresponding to the deterioration degree SOH_n1 read in step S8 is read from the storage unit 120.

In step S10, the discharge capacity correction amount COD_SOH_n is calculated by substituting ΔVa_n calculated in step S7 for the variable x of the discharge capacity correction function F (SOH_n1, x).
COD_soh_n = F (SOH_n1, ΔVa_n)
In step S11, the current discharge capacity COD_now is calculated from the current voltage V_now and the discharge capacity correction amount COD_SOH_n calculated in step S10 using the following equation.
COD_now = V_now-COD_SOH_n

  In step S12, the current discharge capacity COD_now calculated in step S11 is compared with a discharge capacity threshold value COD_Th, and when the current discharge capacity COD_now is greater than the threshold value COD_Th, it is determined that the discharge capacity of the storage battery 10 is maintained (step). S13) On the other hand, when the current discharge capacity COD_now is less than or equal to the threshold value COD_Th, it is determined that the discharge capacity is insufficient (step S14). This determination result can be appropriately output to the state output means 130 to notify the driver or the like.

  As described above, according to the state detection method and state detection device for the electricity storage device of the present embodiment, it is determined whether the discharge capability is appropriately maintained regardless of whether charging / discharging is stopped or not. It becomes possible. In the present embodiment, the previous SOH_n1 closest to the present stored in the storage unit is used as the deterioration degree SOH required for calculating the discharge capacity correction amount, but the change in SOH is sufficiently small in the short term. Therefore, even if SOH_n1 is used, the current discharge capacity COD_now can be estimated with high accuracy.

(Second Embodiment)
The state detection method of the electrical storage device which concerns on the 2nd Embodiment of this invention is demonstrated using FIG. FIG. 3 is a flowchart for explaining the flow of processing of the state detection method for the power storage device of this embodiment. In this embodiment, in the state detection at the time of charge / discharge stop, determination of the discharge capability reflecting the short-term transient change after charge / discharge stop is possible.

  Below, the influence which COD of an electrical storage device receives from the transient change after a charge / discharge stop is demonstrated first. FIG. 4 shows the relationship between the SOH during discharge and the discharge capacity COD. In FIG. 4, the voltage measurement value (D1) when the storage device is stabilized after 20 hours have elapsed after the discharge is stopped is shown on the vertical axis as the discharge capacity COD, and the SOH calculated under the conditions is shown on the horizontal axis. . Moreover, although the broken line L1 which approximates a voltage measurement value was shown together, it turns out that there exists a one-to-one relationship between SOH and COD as the broken line L1 shows. From this, it can be seen that the COD can be obtained with high accuracy by calculating the stable SOH with high accuracy.

  On the other hand, the influence of the transient change when the electricity storage device after charging is not stable is examined below. FIG. 5 shows a transient change in the OCV after the charging is stopped. FIG. 4A shows the change in the OCV when the horizontal time axis is shown in a logarithmic scale, and FIG. 4B shows the same graph when the horizontal time axis is a linear scale. The change of OCV of this is typically shown. As shown in the figure, after the charging is stopped, the transient change due to the charging gradually relaxes, and the OCV gradually converges to the stable OCV.

  However, as the elapsed time after stopping charging is shorter, the influence of transient change due to charging is greater, so if discharging is performed at that time, it is considered that the influence of the previous charging is strongly affected. Therefore, FIG. 6 shows the change over time in the amount of voltage drop when discharging is performed at a plurality of time points with different elapsed times after stopping charging. Here, the elapsed time from the stop of charging is 30 seconds (reference t1), 100 seconds (reference t2), 300 seconds (reference t3), 3600 seconds (reference t4), 36000 seconds (reference t5), and 72000 seconds (reference) It shows the change over time in the amount of voltage drop when discharging is performed at time t6). Here, the discharge of 100 [A] is continued for 30 seconds as the discharge.

  FIG. 6 shows that the amount of voltage drop increases as the elapsed time after stopping charging is shorter. In particular, the amount of voltage drop (symbol t1) when discharging is performed when 30 seconds have elapsed after stopping charging is larger than when the elapsed time from stopping charging to starting discharging is made longer. If the elapsed time from the stop of charging is increased to a certain extent, the difference in voltage drop is hardly observed. Since the difference in the voltage drop amount ΔVa affects the COD, when determining the COD when the elapsed time from the stop of charging is short, the correction of the COD corresponding to the difference in the voltage drop amount ΔVa is performed. preferable.

In the present embodiment, it is considered that the difference in the voltage drop amount ΔVa is caused by a change in the deterioration degree SOH_fast due to a fast transient change, and SOH_fast is calculated based on Expression (7), and is created in advance and stored in the storage unit 120. SOH is calculated using the function G (SOH_fast, SOH_slow) shown in the stored equation (8). Here, SOH_slow indicates the degree of deterioration due to a slow transient change calculated when the most recent charge / discharge stop. In order to accurately calculate the degradation degree SOH_fast due to a fast transient change, a voltage measurement value is used for a fast reaction rate relaxation function f _i (t) of the discharge capacity correction function F (SOH, ΔVa). To optimize. This optimization is possible after a predetermined time (first relaxation time) has elapsed since the charge / discharge stop.

  On the other hand, when determining COD when the elapsed time from the stop of discharge is long, the influence of the voltage drop ΔVa is small, and the accuracy of the SOH described with reference to FIG. 4 has a great influence. In addition, although the above-mentioned FIGS. 4-6 demonstrated the influence of the transient change after a charge stop, it is the same also about the influence of the transient change after a discharge stop.

  In the state detection method of the electricity storage device of the present embodiment, when the elapsed time from the charge / discharge stop is short, SOH_fast corresponding to the difference in the voltage change amount ΔVa due to the fast transient change is accurately calculated, and the discharge is performed using this. Estimating capacity COD. Here, the elapsed time from the stop of charging / discharging for classifying fast transient changes will be described below with reference to FIG. Said 1st relaxation time can be made into the elapsed time which distinguishes this quick transient change. Fig.7 (a) shows the time change of OCV (code | symbol 71) and OCV variation | change_quantity (DELTA) V (code | symbol 72) after a charge stop in a lead liquid storage battery (battery capacity 48 [Ah]), FIG.7 (b) is. The time change of OCV (code | symbol 73) and OCV variation | change_quantity (code | symbol 74) after charge stop in a lead small seal type storage battery (battery capacity 5.5 [Ah]) is shown.

  In the liquid storage battery shown in FIG. 7A, it takes a long time for the electrolyte to stabilize because of its structure, and it cannot be said that the absolute value of the OCV variation ΔV does not become smaller than 0.2V. Therefore, in FIG. 7A, the elapsed time t_fast from the charge / discharge stop when the absolute value of the OCV change amount ΔV decreases to approximately 0.2 V is set as the elapsed time corresponding to the fast transient change. On the other hand, in the sealed storage battery shown in FIG. 7B, the time taken for the electrolyte solution to stabilize is short due to its structure, and the elapsed time from the stop of charging / discharging when the absolute value of the OCV variation ΔV decreases to 0.3V. Let time t_fast be an elapsed time corresponding to a fast transient change. The elapsed time t_fast corresponding to the fast transient change is used as the first relaxation time below.

  The state detection method of the electrical storage device of this embodiment is demonstrated below using the flowchart shown in FIG. From the start of the n-th state detection to the determination of whether or not charging / discharging is stopped in step S3, the same processing as steps S1 to S3 shown in the flowchart of FIG. 1 is performed. Moreover, when it determines with charging / discharging in step S3, step S7-S10 (the above is made into the process block A) of FIG. 1, step S11, and step S12-S14 (the above is made into the process block B), and Do the same process.

  On the other hand, if it is determined in step S3 that charging / discharging is not being performed (charging / discharging is stopped), the same processing as in steps S4 and S5 in FIG. It is determined whether or not it is longer than the relaxation time. Then, when the elapsed time is equal to or shorter than the first relaxation time, the processing block A, step S11, and processing block B are performed as in the first embodiment. On the other hand, if it is determined in step S20 that the elapsed time from the charge / discharge stop is longer than the first relaxation time, the following steps S21 to S27 are performed in the present embodiment.

  In step S21, the voltage change amount ΔVa_n is calculated in the same manner as in step S7 of the processing block A. In the next step S22, the deterioration degree SOH_fast_n due to a fast transient change is calculated using equation (7). In step S23, the deterioration degree SOH_slow_n due to the slow transient change stored in the storage unit 120 is read. In step S24, the SOH calculation formula G (SOH_fast, SOH_slow) is read from the storage unit 120. In step S25, the current SOH_n is calculated by substituting the calculated SOH_fast_n and the read SOH_slow_n into SOH_fast and SOH_slow of the SOH calculation formula G (SOH_fast, SOH_slow), respectively.

In step S26, as in step S9, the discharge capability correction function F (SOH_n, x) corresponding to the deterioration degree SOH_n calculated in step S25 is read from the storage unit 120. In step S27, the discharge capacity correction amount COD_SOH_n is calculated by substituting ΔVa_n calculated in step S21 for the variable x of the discharge capacity correction function F (SOH_n, x).
COD_soh_n = F (SOH_n1, ΔVa_n)
Thereafter, in step S11, the current discharge capacity COD_now is calculated from the current voltage V_now and the discharge capacity correction amount COD_SOH_n calculated in step S27. Further, the processing of the processing block B is performed using the current discharge capacity COD_now.

  According to the state detection method of the electricity storage device of the present embodiment and the state detection device of the electricity storage device of the present embodiment using the state detection method, it is possible to appropriately discharge regardless of whether charging / discharging is stopped or not. In addition to the use of SOH_n1 of the first embodiment, the deterioration degree SOH is calculated based on fast transient characteristics when the charge / discharge stop time is short. It is possible to estimate the current discharge capacity COD_now with higher accuracy.

(Third embodiment)
The state detection method of the electrical storage device which concerns on the 3rd Embodiment of this invention is demonstrated using FIG. FIG. 8 is a flowchart for explaining the flow of processing of the state detection method for the power storage device of this embodiment. In this embodiment, as the state detection at the time of charge / discharge stop, the discharge capability reflecting the transient change after the charge / discharge stop can be calculated. That is, during charging / discharging of the electricity storage device, not only the deterioration degree SOH_fast due to the fast transient change but also the deterioration degree SOH_slow due to the slow transient change is calculated to obtain the deterioration degree SOH with high accuracy, and this is used to discharge the electricity storage device. Judgment is made by estimating the ability with high accuracy. Hereinafter, the elapsed time corresponding to the slow transient change is referred to as a second relaxation time.

  In the flowchart of FIG. 8, from the start of the n-th state detection until the determination of whether the elapsed time of step S20 is greater than the first relaxation time, the state detection method of the second embodiment shown in the flowchart of FIG. Perform the same process as Then, when it is determined in step S20 that the elapsed time is equal to or shorter than the first relaxation time, the processing block A, step S11, and processing block B in FIG. 3 are performed. On the other hand, when it is determined in step S20 that the elapsed time is longer than the first relaxation time, the voltage change amount ΔVa_n is calculated in step 21 as in the second embodiment, and then the process proceeds to step S30.

  In step S30, it is determined whether or not the elapsed time from the charge / discharge stop is longer than the second relaxation time. As a result, when the elapsed time is equal to or shorter than the second relaxation time, steps S22 to S27 (processing block C) are performed as in the second embodiment. On the other hand, if it is determined in step S30 that the elapsed time from the charge / discharge stop is longer than the second relaxation time, the following steps S31 to S34 are performed in the present embodiment.

  In step S31, the OCV change amount ΔV_n is calculated based on equation (4), and using this, the discharge capacity correction function F (SOH, ΔVa) is optimized from the relationship of equation (5) in step S32. In step S33, the current deterioration degree SOH_n is calculated using equations (7) and (8). Further, in step S34, the discharge capacity correction amount COD_SOH_n is calculated by substituting ΔVa_n calculated in step S21 and SOH_n calculated in step S33 into the optimized discharge capacity correction function F (SOH, ΔVa).

  Thereafter, in step S11, the current discharge capacity COD_now is calculated from the current voltage V_now and the discharge capacity correction amount COD_SOH_n calculated in step S27. Further, the processing of the processing block B is performed using the current discharge capacity COD_now.

  According to the power storage device state detection method of the present embodiment and the power storage device state detection device of the present embodiment using the state detection method, the discharge capacity is appropriate regardless of whether charging / discharging is stopped or not. In addition to being able to determine whether or not the current discharge capacity is maintained, it is possible to calculate the deterioration SOH with high accuracy regardless of the elapsed time after stopping when charging / discharging is stopped. COD_now can be estimated.

(Fourth embodiment)
The state detection method of the electrical storage device which concerns on the 4th Embodiment of this invention is demonstrated using FIG. FIG. 9 is a flowchart for explaining the flow of processing of the state detection method for the power storage device of this embodiment.

  When the state of the power storage device is detected after charging / discharging is stopped, the transient change greatly varies depending on the previous charging / discharging history. For example, in a storage battery mounted on an automobile, various charging and discharging operations are repeated during vehicle operation. Therefore, migration, precipitation, convection, diffusion, etc. that occur in the electrolyte in the storage battery vary depending on vehicle operation conditions. Therefore, the transient change of the storage battery after stopping charging / discharging differs depending on the vehicle operating conditions up to that point, and it is impossible to create a reproducible stop state that can be regarded as the same or the same tendency.

  The present embodiment has been made to solve these problems, and provides a storage device state detection method and apparatus for detecting a state by reducing the influence of charge / discharge before stopping the storage device. In the present embodiment, when the state detection is performed after the charge / discharge stop, the storage battery 10 is charged with a predetermined capacity immediately after the charge / discharge stop (hereinafter referred to as pre-state detection charge), and after the pre-state detection charge is completed, the electricity storage device. Detect the state of For example, 5% of the rated capacity may be charged as the pre-state detection charging.

  The flowchart shown in FIG. 9 has the same processing flow as the state detection method of the third embodiment shown in FIG. 8 except immediately after the charge / discharge stop. In this embodiment, the flow depends on the elapsed time after the stop. It is possible to estimate the current discharge capacity COD_now with high accuracy by calculating the deterioration degree SOH with high accuracy. In addition to this, in this embodiment, if it is determined in step S4 that charging / discharging has just stopped, charging before state detection is performed in step S40. By performing such pre-state detection charging, the power storage device shifts to a reproducible transient change state. This makes it possible to detect the state in a reproducible transient state that can be regarded as equivalent or have the same tendency, and to detect the state of the power storage device with higher accuracy.

The state detection method and apparatus of the power storage device of the present invention described above are not limited to power storage devices mounted on conventional engine-driven vehicles, but include electric vehicles, mobile phones, backup batteries that operate during power outages, and It can be applied to a power storage device used for leveling the power of natural energy generated by sunlight or wind power in cooperation with a power system, and a system incorporating the power storage device. The state detection method and apparatus for an electricity storage device of the present invention are not limited to the above applications as long as the electricity storage device is mounted and monitoring or state determination is necessary. Examples of the electricity storage device include a storage battery, a capacitor, and the like, which are devices that can increase or decrease the energy inside the device via the movement of electrons or ions and take out the internal energy as electric power from the outside. For example, there are a Li ion battery, a Ni hydrogen battery, a sodium-sulfur battery, a lead battery, a capacitor, and the like, which can be applied to a power storage system that combines these. The example of the said electrical storage device is a part, and is not limited to the said storage battery or a capacitor.

According to the storage device state detection method and apparatus of the present invention, the discharge capability of the storage device can be determined even when the system is not stopped. Disappear. In addition, since the method for determining the discharge capability of the power storage device is constructed with an algorithm that calculates the condition that is strongly influenced by factors external to the power storage device and other conditions, it is possible to use the method according to the situation. As a result, the selection range of the control method based on the determination result is widened, and a more flexible system operation is possible.

Below, the state detection method after a charge / discharge stop is demonstrated still in detail using a reference example.
In the method and apparatus for detecting the state of the electricity storage device of the first reference example, the transient change of the electricity storage device after the charge / discharge stop is viewed as the change in voltage measurable from the electricity storage device. In other words, the voltage when the storage device stops charging / discharging and reaches a state where the predetermined stability condition is satisfied is defined as the stable voltage at stop, and the amount of change from the stable voltage at stop after the charge / discharge stop is used. To detect the state of the electricity storage device in a transient state. Hereinafter, the amount of change from the stable voltage at the stop of the voltage measurement value when the time t has elapsed since the storage device has stopped charging / discharging is referred to as the stop voltage change.

  In the storage device state detection method and apparatus according to the present reference example, a relaxation function F (t) that depends on a predetermined state amount of the storage device is created in advance as a function for calculating the amount of voltage change at the time of stop. Used. Then, the relaxation function F (t) is optimized using the amount of change in the stop voltage obtained from the voltage measurement value, and the state is detected by estimating a predetermined state quantity from the optimized relaxation function F (t). Yes. In the state detection method of this reference example, the voltage state immediately before the charge / discharge stop is detected, the predetermined state quantity is estimated using the above relaxation function F (t), and the estimated state quantity is set in advance. By comparing with each criterion, it is determined whether or not the discharge capability (COD) of the electricity storage device is appropriately maintained. As the predetermined state quantity, for example, SOH (State of health) which is an indicator of the degree of deterioration of the power storage device, SOC indicating the remaining capacity, or the like can be used.

  There are transient changes in electricity storage devices after charge / discharge stoppages, from those with fast reaction speeds, such as ion generation / annihilation reactions, to those with slow reaction speeds, such as electrolyte migration. It affects the change in the state quantity. Therefore, in the state detection method of the electricity storage device of this reference example, the change in the state quantity for each reaction rate is estimated using the relaxation function F (t), and these are integrated to determine the state quantity. For example, the state quantity at the time when the elapsed time after the end of charge / discharge is short is determined in consideration of the influence of the slow reaction rate.

  As the stable voltage at the time of stop, an open-circuit voltage OCV (hereinafter referred to as a stable time OCV) of the electricity storage device when a sufficient time has elapsed since charging / discharging is stopped is known. OCV is a voltage between terminals when the terminal of the electricity storage device is opened and discharge is stopped. The stable voltage at the time of stop used in the method for detecting the state of the power storage device of the present reference example is not limited to the OCV, and when the transient influence on the power storage device is limited, the stable voltage at that time can be used. . As an example, a minute current (dark current) may be supplied to the load control device while the power supply from the power storage device to the load is stopped. Even when the load is stopped, the voltage when a sufficient time elapses after the load is stopped can be set as the stable voltage at the time of stop.

  In addition, even when the charge / discharge amount from the electricity storage device is always a constant value, the transient effect on the electricity storage device is considered to be sufficiently small, so when sufficient time has passed since the load was stopped. The voltage can be a stable voltage when stopped. In this way, when the current due to charging / discharging is small or constant and the influence on the transient change inside the electricity storage device is limited within a predetermined range, when the power supply to the load is stopped, In addition to determining that the discharge has stopped, the voltage when a long time has elapsed after stopping the charge / discharge in a state where a minute current or a constant current is continued can be set as a stable voltage at the time of stop. In this case, it is preferable that a voltage correction amount for correcting a voltage change due to a minute current or a constant current is determined in advance, and the voltage measurement value is corrected using this.

The following description will be made using a stable OCV as an example of a stable voltage at a stop. When the OCV at the time of stability is used, the state quantity SOC can be expressed by the following equation using the relationship shown in FIG.
SOC = FS (OCVs ′ (SOC ′, SOH, T)) (1-1)
OCV _s (SOC, SOH, T) = lim (V _mes (t)) (1-2)
Here, OCV _s represents the stable OCV calculated this time, OCV ′ represents the previously calculated stable OCV, SOC ′ represents the remaining capacity of the previous calculation, and T represents the temperature of the power storage device. In addition, lim in the above expression indicates that the elapsed time t from the charge / discharge stop is infinite, and the right side of the expression (1-2) indicates that the elapsed time after the charge / discharge stop is infinite. The voltage measurement value V _mes (t) of the electricity storage device is shown. Similarly, when using a stable voltage at the time of stop other than the stable OCV, a relational expression similar to the above can be created in advance with the SOC.

  In the above equation, the SOC is determined depending on the previously calculated OCVs ′, and at the same time, the OCVs also depends on the SOC, and further changes depending on the state quantity SOH and the temperature T of the power storage device. It shows that Moreover, since OCVs depends on another state quantity SOH, the state quantity SOC also depends on SOH, and it is necessary to perform each update at an appropriate timing.

OCV _s is V _mes (t) when the elapsed time t from the charge / discharge stop is infinite as shown in the equation (1-2). However, in practice, the change in V _mes (t) is sufficient. It can be set to V _mes (t) at the time of elapsed time t that is considered to be smaller. Further, when the electricity storage device is a liquid lead-acid battery, OCV _s is V _mes (t) when the amount of change in OCV per hour is 5 mV or less, or when 20 hours have elapsed since charging / discharging was stopped. It can be. Below, the storage device state detection method of the present invention will be described by taking as an example the case where the storage device is a storage battery such as a liquid lead storage battery.

In the following _description , V _mes (t) when 20 hours have elapsed from the stop of charging / discharging of the storage battery is defined as OCV _20hr of the following formula, and this is used for OCV _s .
OCV _20hr = V _mes (t = 20hr)
OCV _s (SOC, SOH, T) ≒ OCV _20hr (1-3)

When the amount of change from the stable OCV of the voltage measurement value V _mes (t) after charge / discharge stop, that is, the OCV change amount (voltage change amount at stop) is ΔV (t),
_{ΔV (t) = V mes (} t) -OCV 20hr (1-4)
It can be expressed as. This voltage change amount ΔV (t) has been handled including all transient changes using the term “polarization” in the conventional definition of electrochemistry. However, since ΔV (t) is a voltage change caused by the relaxation process until the stable OCV is approached, it is influenced by the following factors of voltage change. Factors of voltage change include the electrode plate state, the ion concentration in the vicinity of the electrode plate, their solid-phase reaction, solid-liquid reaction, and precipitation and convection of the electrolyte, and ion movement accompanying diffusion. ΔV (t) is considered to be caused by a combination of relaxation processes having different reaction rates. Therefore, since the transient change after charging / discharging of the electricity storage device 11 includes reaction processes with different speeds, in order to determine the discharging capability of the electricity storage device 11 after stopping charging / discharging with high accuracy, the reaction rate It is preferable to detect the state using a method capable of evaluating the state change for each.

ΔV (t) is expressed as follows using a function F (t) made up of m polynomials according to the difference in reaction rate.
ΔV (t) = F (t)
= F ₁ (t) + f ₂ (t) +... F _m (t) = Σf _i (t) (1-5)
In the above relaxation function F (t), each term f _i (t) indicates the contribution to the voltage change in the relaxation process with different reaction speeds of the storage battery. Hereinafter, the relaxation function f _i (t) for each reaction speed. And Each f _i (t) is a function that depends on the deterioration degree SOH, which is the state quantity of the storage battery, the remaining capacity SOC (ion concentration), and the temperature T. The relaxation function f _i (t) for each reaction rate in the equation (1-5) is optimized by using ΔV (t) calculated from the voltage measurement value V _mes (t) after the charge / discharge stop. Can be determined.

In the state detection system using the state detection method of this reference example, the initial values SOC ⁰ , SOH _i ⁰ , and OCV _20hr ⁰ of SOC, SOH, and OCV _20hr before the state detection is started are _stored in the state detection system. Can be set as follows using the respective reference values SOC ^{ref (0)} , SOH _i ^{ref (0)} , and OCV _20hr ^{ref (0)} stored in advance.
SOC ⁰ = SOC ^{ref (0)}
SOH _i ⁰ = SOH _i ^{ref (0)}
OCV _20hr ⁰ = OCV _20hr ^{ref (0)}
Here, the reference values SOC ^{ref (0)} , SOH _i ^{ref (0)} , and OCV _20hr ^{ref (0)} are values acquired in advance by separate batteries.

The relaxation function F (1-5) representing the OCV variation ΔV (t) after the n-th (n is an integer of 1 or more) charge / discharge stop after the state detection is started by the state detection system. t) and the relaxation function f _i (t) for each reaction rate are F ⁿ (t) and f _i ⁿ (t), respectively, and SOC and SOH corresponding to the i-th reaction rate (respectively SOC ⁿ and SOH _i ⁿ ), the relaxation function fi _n (t) for each reaction rate is expressed by the following equation.
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * g (T) (1-6)
^{_{Here, f i ref (t),}} SOC ref, SOH i ref is, f _i (t) in the predetermined initial state (e.g. unused state), SOC, a SOH _i, g (T) is It is a function representing temperature dependence.

In the equation (1-6), when the temperature T and the SOC are constant regardless of the time, SOH _i ⁿ is calculated as follows: SOH _i ⁿ = {f _i ⁿ (t) / f _i ^ref (t)} * SOH _i ^ref (1-7)
It can be calculated from Therefore, to optimize the f _i ⁿ (t) of formula (1-5) to [Delta] V (t) that is calculated from the voltage measured value _{V mes (t), SOH i} n from the equation (1-7) by using the Can be calculated.

When SOH _i ⁿ for each transient response with different reaction rates is calculated from the equation (1-7), the total SOH ⁿ calculated by integrating these is
SOH ⁿ = (SOH ₁ ⁿ , SOH ₂ ⁿ ,..., SOH _m ⁿ ) (1-8)
It can be expressed as For example, if m coefficients are A to M for m SOH _i ,
SOH ⁿ = A * SOH ₁ ⁿ + B * SOH ₂ ⁿ +... + M * SOH _m ⁿ
= A * {f ₁ ⁿ (t) / f ₁ ^ref (t)} SOH ₁ ^ref +
B * {f ₂ ⁿ (t) / f ₂ ^ref (t)} SOH ₂ ^ref +... +
M * {f _m ⁿ (t) / f _m ^ref (t)} SOH _m ^ref (1-8-1)
It can be expressed as. However, the formula (1-8-1) is an example representing the relational expression of the formula (1-8), and is not limited thereto. Using the SOH ⁿ calculated as described above, it is possible to detect the deterioration state of the storage battery. Similarly, SOC ⁿ which is another state quantity can be calculated using the optimized relaxation function F (t).

Since the relaxation function F (t) shown in the equation (1-5) has a relaxation function f _i (t) for each reaction rate with different reaction rates, the elapsed time after the nth charge / discharge stop. Is short, f _i ⁿ (t) corresponding to a slow reaction rate cannot be optimized. As a result, SOC ⁿ by using the relaxation function F (t), it is not possible to update the SOH _i ^n. Therefore, until the optimization of f _i ⁿ (t) corresponding to the slow reaction rate is possible, instead of SOC ⁿ and SOH _i ⁿ , the values SOC ⁿ⁻¹ and SOH _i ⁿ⁻ at the previous charge / discharge stop time are used. ¹ is used, and the expression (1-6) is approximately expressed as the following expression.
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ⁻¹ / SOC _i ^ref }
* {SOH _i ^n-1 / SOH _i ^ref } * g (T) (1-6-1)

When the equation (1-6-1) can be used for f _i ⁿ (t) corresponding to a slow reaction rate, it is possible to detect the state from a point in time after a short period of time after stopping charging and discharging. It becomes. In particular, when charging / discharging is performed only below a predetermined threshold value, the relaxation function F ⁿ (t) using SOC ⁿ⁻¹ and SOH _i ⁿ⁻¹ after the end of the previous charging / discharging is used for state detection. It becomes possible.

On the other hand, for the remaining capacity SOC of the storage battery, the charge / discharge current during the period from the end of the previous (n-1) charge / discharge stop until the current (nth) charge / discharge stop The remaining amount change ΔSOC can be calculated by integration, and SOC ⁿ can be calculated by correcting the previous remaining amount SOC ⁿ⁻¹ using this. That is,
SOC ^n-1 '= SOC ^n-1 + ΔSOC
And using this in place of SOC ⁿ , equation (1-6) can be approximated as:
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ⁻¹ ′ / SOC ^ref }
* {SOH _i ^n-1 / SOH _i ^ref } * g (T) (1-6-2)

Using the SOH _i ⁿ calculated by the equation (1-7), f _i ⁿ (t) is updated by the following equation, and this is used to calculate the SOC _i ⁿ .
f _i ⁿ (t) = f _i ^ref (t) * {SOC _i ⁿ⁻¹ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * g (T) (1-6-3)

From Expression (1-4) and Expression (1-6-3), OCV _20hr can be calculated by the following expression.
OCV _{20 hr} = V _mes (t) −Σ [f _i ^ref (t) * {SOC ⁿ⁻¹ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref }] * g (T) (1-9)
By substituting this OCV _{20 hr} into the equation (1-1), SOC ⁿ can be calculated and used for SOC state detection.

As described above, m reference values f _i ^ref (t) (i = 1 to m) corresponding to m kinds of reaction rates and m deterioration values reference values SOH _i ^ref (i = 1 to m). And m relaxation rate functions f _i ⁿ (t) (i = ^{1 to} m) after the nth charge / discharge stop based on the reference value SOC ^ref of one remaining capacity. Can do. As a result, it is possible to detect OCV, SOC, and SOH reflecting the degree of deterioration corresponding to different reaction rates and to perform highly accurate state detection.

  The state detection method of the electrical storage device of a 1st reference example is demonstrated below using FIG. FIG. 10 is a flowchart showing the flow of processing by the state detection method of this reference example. FIG. 11 is a block diagram showing a schematic configuration of a state detection device using the state detection method of this reference example. The state detection device 210 shown in FIG. 11 is configured to detect the state of the storage battery 1 mounted on the vehicle as an example. Charging means 202 and a load 203 are connected to the storage battery 201, and charging by the charging means 202 and discharging to the load 203 are possible. Further, the storage battery 201 is provided with a temperature measuring unit 201a, a voltage measuring unit 201b, and a current measuring unit 201c, and each measurement value can be input to the state detection device 210 via the input unit 204. Yes. Furthermore, the control apparatus 205 which controls charging / discharging of the storage battery 201 is provided. It is also possible to input control information from the control device 205 via the input means 204 to the state detection device 210.

  The state detection device 210 includes an arithmetic device 211, a fixed storage unit (ROM) 212, a temporary storage unit (RAM) 213, a timer 214, and a state output unit 215. The arithmetic device 211 inputs the temperature measurement value, the voltage measurement value, and the current measurement value of the storage battery 201 using the input unit 204, and stores them in the temporary storage unit 213. Further, the fixed storage means 212 stores a relaxation function fi (t) for each reaction rate and initial values and reference values of various state quantities. The arithmetic unit 211 uses the initial value and reference value stored in the fixed storage unit 212, the voltage measurement value stored in the temporary storage unit 213, and the like to store the storage battery 201 at a predetermined time period counted by the timer 214. It is configured to detect the state and output the result to the state output means 215. The output information of the status output means 215 can supply control parameter information for use by the control device 205.

The state detection method of this reference example is demonstrated below using the flowchart shown in FIG. First, in step S <b> 201, the voltage measurement value and the current measurement value of the storage battery are input using the input unit 204. In the next step S202, it is determined from the input current measurement value whether the charge / discharge stop has been started. If it is determined that the charge / discharge stop has been started, in step S203, the previous voltage measurement value is stored in the temporary storage means 213 as the discharge end voltage _VDE or the charge end voltage _VCE . The next step in the case in step S204, as compared to V ^ref of the reference values stored discharge end voltage V _DE or charging end voltage V _CE in the fixed storage device 212, higher than the reference value V ^ref The process proceeds to S205. On the other hand, if the discharge end voltage V _DE or the charge end voltage V _CE is lower than the reference value V ^ref , it is determined that the discharge capacity COD is insufficient, and the process proceeds to step S213 to indicate the COD shortage as the state output means 215. To output.
Here, V ^ref is a value (for example, 12.8 V) measured in advance with another battery.

If it is determined in step S204 that the discharge end voltage V _DE or the charge end voltage V _CE is equal to or higher than V ^ref, it is determined in step S205 whether charging / discharging is stopped or charging / discharging is resumed. If it is determined that charging / discharging has been resumed, the state detection is terminated. On the other hand, when the charge / discharge stop is continued, the voltage measurement value is set to V _mes in step S206 and stored in the temporary storage means 213. In the next step S207, OCV _20hr which is a stable voltage at the time of stop is selected, and ΔV (t) is calculated in step S208 using this and the voltage measurement value V _mes .

  In step S209, the relaxation function F (t) is optimized using ΔV (t) calculated in step S208. Regarding the fitting method, there are various methods of calculation using regression calculation such as the least square method. However, in this fitting, ΔV (20 hr) = 0, so that the regression is simply performed using the sum of exponential functions. If the calculation is performed, the error becomes large. Therefore, by subtracting the slope of the tangent line near ΔV (20 hr) = 0, a function that always satisfies ΔV (20 hr)> 0 (for example, Expression (1-10-4) described later) is introduced, and the difference is calculated. It is desirable to perform fitting with the sum of exponential functions.

In step S210, a predetermined state quantity (hereinafter referred to as S) is estimated using the optimized relaxation function F (t). In step S211, the estimated state quantity S is compared with the reference value S ^ref stored in the fixed storage means 212. When it is determined that the state quantity S satisfies a predetermined condition, the process proceeds to step S212, and the COD is determined. The secured status is output to the status output means 215. On the other hand, if it is determined in step S211 that the state quantity S does not satisfy the predetermined condition, the process proceeds to step S213, and the fact that the COD is insufficient is output to the state output means 215.

The state detection method of the storage battery of the reference example, the formula SOC calculation formula and SOC of (1-1), SOH, reference value SOC corresponding to the initial value of the ^{_{OCV 20hr ref (0), SOH}} ref (0), OCV 20hr ^{ref (0)} is stored in the fixed storage unit 212 in advance, and the initial values thereof are used as SOC ⁰ = SOC ^{ref (0)} , SOH _i ⁰ = SOH _i ^{ref (0)} , OCV _20hr ⁰ = OCV. Set _20hr ^{ref (0)} .

  Details of the processing in step S201 are shown in FIG. In FIG. 12, the timer count value is confirmed at a predetermined confirmation timing, and when the timer count (t_count) exceeds the measurement timing value for the predetermined measurement timing (step S201-2). The voltage and current of the storage battery 201 are input from the input unit 214 (step S201-4).

  FIG. 13 shows an example of a method for determining whether to stop charging / discharging the storage battery 1 in step S202. The charge / discharge stop is determined when the measured current value measured in step S202-2 is equal to or less than a predetermined threshold value stored in the fixed storage unit 212 (step S202-4). Is determined to be parked or stopped, or information indicating that the state detection device 210 is connected to the storage battery 201 is input to the computing device 211 (step S202-1), using these pieces of information. It is also possible to determine whether to stop charging / discharging (step S202-3).

The OCV _20hr selection method in step S207 is shown in the flowchart of FIG. The previous calculated values SOC ^n-1 and SOH ^n-1 are used as SOC ⁿ and SOH ⁿ at the start of the ^nth OCV _20hr calculation (step S207-1). The current temperature T of the storage battery 201 uses the measured value input from the input means 204 (step S207-2). _Assuming that the OCV _20hr selected by this is OCV _20hr ^temp , a relational expression created in advance under h types of conditions combining a plurality of SOC and SOH values and temperatures.
H (SOC_j, SOH_k, T_l) = OCV 20hr ref (h) (h, j, k, l is a natural number)
Using (step S207-4), the OCV _{20 hr} ^temp set by the following equation (step S207-5).
OCV _20hr ^temp = OCV _20hr ^{ref (h)}

In the following, for the sake of simplicity, the formula (1-5) is composed of the following four terms.
F (t) = f _fast (t) + f _slow (t)
= {F _fast1 (t) + f _fast2 (t)} +
{F _slow1 (t) + f _slow2 (t)} (1-10)

As an example, for example, (Equation 1-10) is a function of fast relaxation rate 1: f _fast1 (t) = A * exp (−B * t ^ C) (1-10-1)
Fast relaxation rate function 2: f _fast2 (t) = D * exp (-E * t ^ F) (1-10-2)
Slow relaxation rate function 1: f _slow1 (t) = G * exp (-H * t ^ I) (1-10-3)
Slow relaxation rate function 2: f _slow2 (t) = -a / 72000 * t + b (1-10-4))
This makes it easy to create a function that optimizes ΔV (t). However, this function is complicated or simplified depending on the calculation speed of the calculation device 211, the memory capacity of the fixed storage means 212 and the temporary storage means 213, and the accuracy conditions required for the measurement sensor. May be.

A method for obtaining F ⁿ (t) from ΔV (t) according to the elapsed time of the timer count (step S209) will be described with reference to FIGS. The functions shown by the equations (1-10-1) to (1-10-4) are sections divided by four reference times (10 seconds, 1000 seconds, 36000 seconds, 72000 seconds), and each is dominant. Each coefficient is determined by fitting as follows. Here, the reference time (10 seconds, 1000 seconds, 36000 seconds, 72000 seconds) is an example, and can be set according to the relaxation characteristics of the reaction rate of the storage battery. In addition, the reference time can be changed not only by the reaction speed inside the storage battery but also by the running condition and rest condition in the actual vehicle, the required accuracy of the sensor, and the like.

A method for obtaining F ⁿ (t) from ΔV (t) when the elapsed time after charging / discharging is stopped is shorter than 20 hours will be described with reference to FIG. The original a (step S209-1), the calculated value F ^n-1 after the previous charge-discharge stop (t) when the time t is determined to less than the first reference time (10 seconds), F ⁿ (T) is calculated by the following equation (step S209-2).
F ⁿ (t) = f _fast1 ⁿ⁻¹ (t) + f _fast2 ⁿ⁻¹ (t) +
f _slow1 ^n-1 (t) + f _slow2 ^n-1 (t)} (1-11)

Similarly, when it is determined that the time t is greater than or equal to the first reference time and shorter than the second reference time (1000 seconds) (step S209-3), F ⁿ⁻¹ ( Based on t) and the latest data, F ⁿ (t) is calculated by the following equation (step S209-4).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ⁻¹ (t) +
f _slow1 ^n-1 (t) + f _slow2 ^n-1 (t)} (1-12)

Further, when it is determined that the time t is equal to or longer than the second reference time and shorter than the third reference time (36000 seconds) (step S209-5), F ^n-1 (t) after the last charge / discharge is completed. Based on the latest data, F ⁿ (t) is calculated by the following equation (step S209-6).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ (t) +
f _slow1 ^n-1 (t) + f _slow2 ^n-1 (t)} (1-13)

When it is determined that the time t is equal to or longer than the third reference time and shorter than the fourth reference time (72000 seconds) (step S209-7), F ^n-1 (t) after the end of the previous charge / discharge is completed. Based on the latest data, F ⁿ (t) is calculated by the following equation (step S209-8).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ (t) +
f _slow1 ⁿ (t) + f _slow2 ^n-1 (t)} (1-14)
OCV _20hr ⁿ = F ⁿ (20 hr) by substituting t = 20 hours for F ⁿ (t) obtained from the above equations (1-11) to (1-14).
Is obtained (step S209-11).

When it is determined that the time t is equal to or longer than the fourth reference time (for example, 20 hours) (step S209-7), as shown in FIG. 16, the OCV _20hr ^temp obtained from the latest V _mes (20 hr), ΔV ⁿ (t) = ΔV (t) ^temp + OCV _{20 hr} ^temp −OCV _{20 hr} ⁿ (1-15) based on ΔV (t) recorded so far (ΔV (t) ^temp )
ΔV ⁿ (t) is calculated (step S209-13), and F ⁿ (t) is calculated by the following equation (step S209-15).
F ⁿ (t) = f _fast1 ⁿ (t) + f _fast2 ⁿ (t) +
f _slow1 ⁿ (t) + f _slow2 ⁿ (t)} (1-16)

FIG. 17 shows f _i (t) calculated in the processing of FIGS. 15 and 16 and stored in the temporary storage unit 213, the reference value f _i ^ref (t) previously stored in the fixed storage unit 212, and SOH _i. with ^ref, it shows a flow of processing in step S210 of calculating SOH _i ^n, the SOC. The OCV _20hr ⁿ , the reference value f _i ^ref (t), the SOH _i ^ref and the temperature T ⁿ obtained above are read from the storage means 212 and 213 (steps S210-1 and S213) and stored in the fixed storage means 212. SOC ^ref_n is calculated by substituting each value into the relational expression of the function I (OCV _{20hr —} ⁿ , SOH _i ⁿ , T ⁿ ) = SOC ^ref_n (step S210-6), and SOC ⁿ = SOC ^ref_n Is calculated (step S210-7).

As an example of optimization of the relaxation function F (t) in the storage battery state detection method of the present reference example, an example of changes in each term when the relaxation function F (t) is expressed as in Expression (1-10) As shown in FIG. FIG. 18 is a graph showing changes in ΔV (t) (= F (t)) when the horizontal axis is the elapsed time from the end of charge / discharge, and reference numerals 251 to 254 denote the expressions (1-10), respectively. The change of each term ( _ffast1 (t), _ffast2 (t), _fslow1 (t), _fslow2 (t)) is shown. Moreover, the code | symbol 250 has shown the true value and the code | symbol 255 has shown the value of F (t) calculated from Formula (1-10). It is shown that ΔV (t) can be predicted with high accuracy by using F (t) of this reference example.

In the following, the degree of stratification with slow reaction rate (diffusion of electrolyte, etc.) is SOH ₁ (i = 1) in formula (1-7), and SOH ₁ ⁿ after the ^nth charge / discharge is
SOH ₁ ⁿ = f _slow ⁿ (t) / f _slow ^ref * SOH ₁ ^ref
= {F _slow1 ⁿ (t) + f _slow2 ⁿ (t)} /
{F _slow1 ^ref (t) + f _slow2 ^ref (t)} * SOH ₁ ^ref
(1-17)
It shall be calculated by In the above, f _i ⁿ (t) and f _i ^ref (t) in the expression (1-7) are further added to the sum of two terms {f _slow1 ⁿ (t) + f _slow2 ⁿ (t)}, {f _slow1 ^ref ( t) + f _slow2 ^ref (t)}.

As an example, using a liquid lead acid battery of size model number 55D23 manufactured by Furukawa Battery, under the conditions of an environmental temperature of 25 ° C. and a DOD (Depth of discharge) of 10%, 20 charge / discharge cycles from an unused state are performed 50 times. And 100 runs. Based on the measurement data after 20 cycles of charge / discharge, 50 cycles of charge / discharge, and 100 cycles of charge / discharge, 5 hours elapsed (t = 5 hours) from the end of charge / discharge. SOH ₁ ⁿ is calculated from the OCV change amount f _i ⁿ (5 hr) at the time as follows.
^{_{SOH 1 50 = {f slow1 50}} (5hr) + f slow2 50 (5hr)} /
{F _slow1 ²⁰ (5 hr) + f _slow2 ²⁰ (5 hr)} * SOH ₁ ²⁰ (1-18)
SOH ₁ ¹⁰⁰ = {f _slow1 ¹⁰⁰ (5 hr) + f _slow2 ¹⁰⁰ (5 hr)} /
{F _slow1 ²⁰ (5 hr) + f _slow2 ²⁰ (5 hr)} * SOH ₁ ²⁰ (1-19)

FIG. 19 shows f _slow ⁿ (t) / f _slow ²⁰ (t) calculated from the measurement data. Reference numerals 261, 262, and 263 indicate f _slow ²⁰ (t), f _slow ⁵⁰ (t), and f _slow ¹⁰⁰ (t), respectively, and reference numerals 264 and 265 indicate f _slow ⁵⁰ (t) / f _slow ²⁰ ( t), f _slow ¹⁰⁰ (t) / f _slow ²⁰ (t). From the figure, at the time of t = 18000 seconds, for example, {f _slow1 ⁵⁰ (5 hr) + f _slow2 ⁵⁰ (5 hr)} /
{F _slow1 ²⁰ (5hr) + f _slow2 ²⁰ (5hr)}
= F _slow ⁵⁰ (5hr) / F _slow ²⁰ (5hr)
= 1.52

Similarly,
f _slow ¹⁰⁰ (5hr) / f _slow ²⁰ (5hr)
= 1.63
Is obtained. Thus, it becomes possible to grasp the change in the battery state according to the number of charge / discharge cycles from the change amount F (t) of the OCV.

Further, OCV when the elapsed charge and discharge after the end of 20 hours as an example, with respect to the charge-discharge cycle number ^{_{20,50,100 OCV 20hr 20 = 12.896 [V}} ]
OCV _20hr ⁵⁰ = 13.032 [V]
OCV _20hr ¹⁰⁰ = 13.036 [V]
FIG. 20 shows the relationship between f _slow ⁿ (t) / f _slow ²⁰ (t) and OCV _20hr ²⁰ described above. The result shown in FIG. 20 can be used for the stable OCV estimation formula for estimating the OCV _{20 hr of the} same type of storage battery.

  As described above, according to the present invention, it is possible to provide a state detection method for a storage battery that performs state detection by evaluating deterioration due to reaction processes having different speeds. By detecting the deterioration degree SOH of the battery, it is possible to accurately detect the remaining capacity SOC.

The state detection method of the electrical storage device which concerns on a 2nd reference example is demonstrated below using FIG. FIG. 21 is a flowchart showing a process flow according to the state detection method of this reference example. In this reference example, after determining COD based on the discharge end voltage V _DE or the charge end voltage V _CE in step S204 of the first reference example, the remaining capacity SOC _stop ⁿ at the time of charge / discharge stop in step S221. Is used to determine the COD. That is, in step 221, the remaining capacity SOC _stop ⁿ is compared with the reference value SOC _stop ^ref stored in the fixed storage means 212. If the remaining capacity SOC _stop ⁿ is greater than or ^equal to the reference value SOC _stop ^ref , the next step is performed. Proceeding to S205 and thereafter, if it is smaller than the reference value SOC _stop ^ref, it is determined that the COD is insufficient, and the process proceeds to step S213. Thereby, the discharge capability of the storage battery 201 can be determined with higher accuracy.

A method of calculating the remaining capacity SOC _stop ⁿ when charging / discharging is stopped will be described with reference to FIG. With respect to the SOC _stop ^n-1 calculated at the time of stopping the charging / discharging, the SOC increased / decreased after the charging / discharging is restarted until the current charging / discharging stop (this is set as the remaining capacity increase / decrease amount ΔSOC) is corrected. By doing so, the remaining capacity SOC _stop ⁿ at the current charge / discharge stop can be calculated. The remaining capacity increase / decrease amount ΔSOC can be calculated by integrating the charge / discharge current of the storage battery 1 from the previous charge / discharge restart to the current charge / discharge stop.

In this reference example, the remaining capacity increase / decrease amount can be calculated with higher accuracy by further performing a predetermined correction on the ΔSOC calculated as described above. In the state detection method of this reference example, the remaining capacity SOC _stop ⁿ when charging / discharging is stopped is calculated by the following equation.
SOC _stop ⁿ = SOC _stop ^n-1 + ΔSOC * η ₁ ^n-1 * η ₂ ^n-1 (1-20)
Here, η ₁ ^n-1 is a function of slow relaxation rate f _slow (10 hr) (f _{slow1 in} formula (1-10-3) or formula (1-10-4) as shown in FIG. a correction coefficient which is determined depending of the ^{_{f slow2), η 2 n-}} 1 , as shown in FIG. 22 (b), is a correction coefficient determined in dependence on the charging end voltage V _CE ⁿ . These correction coefficients correct the charging efficiency of the storage battery 201.

The state detection method of the electrical storage device which concerns on the 3rd reference example of this invention is demonstrated below using FIG. FIG. 23 is a flowchart illustrating a process flow according to the state detection method of this reference example. In this reference example, the processing method of steps S210 and S211 is changed to step S230 in the processing of the second reference example shown in FIG. In steps S210 and S211 of the second reference example (the same applies to the first reference example), a predetermined state quantity S is calculated and compared with the reference value S ^ref stored in the fixed storage unit 212. It was determined whether or not the amount S satisfies the condition indicating that the discharge capacity is maintained. On the other hand, in step S230 of this reference example, the state quantity S is evaluated for each reaction rate, and it is determined whether the condition for maintaining the discharge capacity is satisfied for each reaction rate. Also, the determination based on the ratio between the slow reaction rate and the fast reaction rate is performed.

Taking the deterioration degree SOH as an example of the state quantity S, a determination method for each reaction rate and a determination method based on the ratio of the slow reaction rate and the fast reaction rate will be described below. The degree of deterioration SOH _fast ⁿ and SOH _slow ^{n for} each reaction rate can be calculated as follows using equation (1-7).
SOH _fast ⁿ '= {f _fast ⁿ (t) / f _fast ^ref_n (t)} * SOH _fast ^ref
(1-21)
SOH _slow ⁿ = {f _slow ⁿ (t) / f _slow ^ref_n (t)} * SOH _slow ^ref
(1-22)
Furthermore, the total SOH ⁿ obtained by integrating the degradation degrees SOH _fast ⁿ and SOH _slow ⁿ for each reaction rate is expressed as in equation (1-8), and can be calculated from equation (1-8-1), for example. it can.

The degree of deterioration SOH _{fast / slown} calculated based on the ratio between the slow reaction rate and the fast reaction rate can also be calculated by the following equation as described above.
SOH _{fast / slow} ⁿ = {f _{fast / slow} ⁿ (t) / f _{fast / slow} ^ref_n (t)}
* SOH _{fast /} ^slow_ref (1-23)
The degradation degree SOH _{fast / slow} ⁿ calculated based on the ratio of the slow reaction rate and the fast reaction rate is obtained by using the ratio of the slow reaction rate and the fast reaction rate as shown in FIG. It becomes possible to evaluate a change in the degree of deterioration based on a large change event, either a speed transient event or a slow reaction rate transient event.

In order to correct the influence of the remaining capacity SOC _stop ^n, which is the state quantity at the time of charge / discharge stop, and the voltage V _CE ⁿ at the end of charge for SOH _fast ⁿ ′ calculated by the above equation (1-21), The corrected deterioration degree SOH _fast ⁿ is calculated by the following equation. This correction corrects the fact that SOH _fast ⁿ changes as shown in FIG. 25 with respect to a fast reaction rate.
SOH _fast ⁿ = SOH _fast ⁿ '* α ₁ ⁿ * α ₂ ⁿ (1-24)
The correction parameters α ₁ ⁿ and α ₂ ⁿ show changes as shown in FIGS. 26A and 26B, for example, with respect to the remaining capacity SOC _stop ⁿ and the charging end voltage V _CE ⁿ . Accordingly, the change shown in FIGS. 26A and 26B is expressed by a predetermined function (high-speed transient change correction amount calculation formula), so that the correction parameter α _{1 is obtained} from the remaining capacity SOC _stop ⁿ and the charging end voltage V _CE ^{n. n} and α ₂ ⁿ can be calculated.

In the above description, correction of SOH _fast ⁿ has been described. For SOH _slow ⁿ , for example, formulas for calculating correction parameters β ₁ ⁿ and β ₂ ⁿ are created in advance, and correction is similarly performed using the formulas. It is possible.

The SOD _fast ⁿ , SOH _slow ⁿ , and SOH _{fast / slow} ⁿ calculated as described above are used, and the COD of the storage battery 1 can be determined by comparing with the respective reference values as shown in FIG. . In FIG. 27, the state quantity is represented by S _fast or the like, but when SOH is evaluated, it is replaced with SOH _fast ⁿ or the like. In step S231, SOH _slow ⁿ is calculated using equation (1-22), and in step S232, it is compared with the reference value SOH _slow ^ref_n . As a result, when SOH _slow ⁿ is less than SOH _slow ^ref_n , it is determined that the COD is insufficient, and the process proceeds to step S213. Otherwise, the process proceeds to the next step S233.

Similarly, SOH _fast ⁿ is determined in steps S233 and S234, and SOH _{fast / slow} ⁿ is determined in steps S235 and S236. In any case, when a predetermined condition is satisfied, the process proceeds to step S212 and it is determined that the COD is maintained. In this reference example, it is possible to detect the state of the storage battery 1 with high accuracy by performing the processing as shown in FIGS.

  In the above description, the reference example in which SOC and SOH are calculated as the state quantities of the power storage device and the state is detected using the SOC and SOH has been described. The state detection method of the electricity storage device of the present invention is not limited to this, and other state quantities relating to the discharge capability of the electricity storage device can be used. In addition to the SOC and SOH, as a state quantity that can be used for determining the discharge capability of the electricity storage device, there is a concentration change amount of the electrolytic solution in the electricity storage device. The density | concentration of electrolyte solution is changing with charging / discharging, and it takes time until it stabilizes even after charging / discharging stops.

Therefore, in order to use the amount of change in the electrolyte concentration for state detection, the electrolyte solution for each term f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t) A density change amount calculation formula for calculating the density change amount is created in advance and stored in the fixed storage unit 212. Then, an electrolyte solution concentration change amount is calculated from the concentration change amount calculation formula using the optimized relaxation function F (t), and state detection is performed by determining whether or not this satisfies a predetermined condition. Can be. By further using the amount of change in the electrolyte concentration in the state detection method of the electricity storage device, it is possible to detect the state with high accuracy.

  Another state quantity that can be used to determine the discharge capability of the electricity storage device is a change in the concentration distribution (stratification) of the electrolyte solution. An example of the concentration distribution of the electrolytic solution of the electricity storage device is shown in FIG. FIG. 28 schematically shows a state in which the stratification 294 is formed by changing the concentration distribution of the electrolytic solution 293 around the positive electrode 291 and the negative electrode 292. In the electricity storage device, the concentration distribution of the electrolytic solution changes with charge / discharge, and a stratification 294 as shown in the figure is formed. In this stratification, the lateral stratification, which is a deviation of the concentration distribution in the lateral direction (arrow 295) with respect to the liquid surface of the electrolytic solution, and the concentration distribution in the vertical direction (arrow 296) with respect to the liquid surface of the electrolytic solution. There is vertical stratification that is biased. This change in stratification occurs as the electrolyte concentration changes due to charge / discharge, and it takes time to stabilize after stopping the charge / discharge, similar to the change in electrolyte concentration.

Therefore, in order to use the stratification change amount for state detection, the stratification change with respect to the terms f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t). A stratification change amount calculation formula for calculating the amount is created in advance and stored in the fixed storage unit 212. Then, the stratification change amount is calculated from the stratification change calculation formula using the optimized relaxation function F (t), and state detection is performed by determining whether or not this satisfies a predetermined condition. Can be. By using the amount of stratification change in the state detection method of the electricity storage device, it is possible to detect the state with high accuracy.

  As another state quantity that can be used for determining the discharge capability of the electricity storage device, there is a change in the concentration distribution bias (lateral stratification) in the lateral direction with respect to the liquid surface of the electrolytic solution. This change in lateral stratification occurs as the electrolyte concentration changes due to charging / discharging, and it takes time to stabilize after stopping the charging / discharging, similar to the change in electrolyte concentration.

Therefore, in order to use the lateral stratification change amount for state detection, the lateral stratification with respect to the terms f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t). A lateral stratification change amount calculation formula for calculating the change amount of stratification is created in advance and stored in the fixed storage means 212. Then, using the optimized relaxation function F (t), the lateral stratification change amount is calculated from the lateral stratification change calculation formula, and the state detection is performed by determining whether or not this satisfies a predetermined condition. Can be done. By using the amount of lateral stratification change in the state detection method of the power storage device, it is possible to detect the state with high accuracy.

  As another state quantity that can be used for determining the discharge capability of the electricity storage device, there is a change in the concentration distribution (horizontal stratification, vertical stratification) in the horizontal and vertical directions with respect to the liquid surface of the electrolytic solution. When this is the amount of vertical and horizontal stratification change, the amount of vertical and horizontal stratification change occurs as the electrolyte concentration changes due to charge and discharge. take time.

Therefore, in order to use the vertical and horizontal stratification change amount for the state detection, the vertical and horizontal stratification with respect to the terms f _fast (t), f _slow (t) and f _fast (t) / f _slow (t) of the relaxation function F (t). A vertical and horizontal stratification change amount calculation formula for calculating the change amount is generated in advance and stored in the fixed storage unit 12. Then, using the optimized relaxation function F (t), the vertical / horizontal stratification change amount is calculated from the vertical / horizontal stratification change calculation formula, and the state detection is performed by determining whether or not this satisfies a predetermined condition. Can be done. By using the amount of vertical and horizontal stratification change in the state detection method of the power storage device, it is possible to detect the state with high accuracy.

Another state detection method after stopping charging / discharging will be described in more detail.
When detecting the state of an electricity storage device after stopping charging / discharging, the transient change varies greatly depending on the previous charging / discharging history, etc., so it is highly influenced by the charging / discharging history and the discharge capability etc. can be determined with high accuracy. There was a problem that it became difficult.

  For example, in a storage battery mounted on an automobile, various charging and discharging operations are repeated during vehicle operation. Therefore, migration, precipitation, convection, diffusion, and the like that occur in the electrolyte in the storage battery vary depending on vehicle operation conditions. Therefore, the transient change of the storage battery after stopping charging / discharging differs depending on the vehicle operating conditions up to that point, and it is impossible to create a reproducible stop state that can be regarded as the same or the same tendency. As in the state detection method described in Patent Document 1, even when the state change is detected by dividing the transient change after stopping the charge / discharge into components having different time constants, if the transient change of the storage battery after stopping the charge / discharge is greatly different, There is a problem that it is difficult to obtain each time constant component with high accuracy, and it is difficult to detect the state of the storage battery with high accuracy.

  Accordingly, in order to solve these problems, a state detection method and a device for a state of an electricity storage device that detect the state by reducing the influence of charging and discharging before stopping the electricity storage device are provided.

  In the state detection method of the power storage device of the fourth reference example, a state detection mode for appropriately detecting the state of the power storage device is provided in order to appropriately maintain the discharge capability of the power storage device. The state detection mode is a system that includes an electricity storage device.For example, when the operation is stopped and charging / discharging of the electricity storage device is stopped, or when a considerable time has elapsed after the charging / discharging is stopped, It is executed by maintenance personnel. When the state detection mode is requested for the power storage device, the state of the power storage device is detected with high accuracy.

  Hereinafter, the state detection method and state detection device of the power storage device of this reference example will be described by taking a battery mounted on the vehicle as an example of the power storage device. However, the contents described below are not limited to in-vehicle batteries, but can be similarly applied to power storage devices used for photovoltaic power generation, wind power generation, and the like, and power storage devices used for backup power sources such as a stabilized power source and an auxiliary power source. Is.

  The state detection method and apparatus of the electricity storage device of this reference example will be described below with reference to FIGS. FIG. 29 is a flowchart for explaining an outline of the state detection method of the power storage device of this reference example, and FIG. 30 is a block diagram of the state detection device of the power storage device of this reference example.

  The state detection device 400 of this reference example is mounted on the vehicle 310 and detects the state of the power storage device (storage battery) 311, and includes a signal input unit 401, an output display unit 402, a measurement unit 403, and a state detection unit 410. It has. The power storage device 311 is connected to a load 312 such as an in-vehicle electric device, and further connected to an in-vehicle charger 314 such as an alternator. The signal input unit 401 is used to input a signal (hereinafter referred to as a state detection mode start signal) for a user such as a driver to request a state detection mode, and the output display unit 402 is a state detection unit. This is used to notify the user of the result of the above. Since both the signal input unit 401 and the output display unit 402 are used by the driver, it is preferable to provide the signal input unit 401 and the output display unit 402 at or near the driver's seat.

  The state detection unit 410 inputs measurement values such as the voltage and current of the power storage device 311 from the measurement unit 403, and performs processing for detecting the state of the power storage device 311 with high accuracy using the measurement values. In addition, the state detection unit 410 includes a state detection mode switch 411. Instead of inputting the state detection mode start signal from the signal input unit 401, the state detection mode switch 411 is turned on to detect the state. A mode start signal is output to the state detection unit 410. The state detection mode switch 411 is provided so that maintenance personnel can quickly detect the state of the power storage device 311 during maintenance such as during periodic inspection.

  The state detection unit 410 is configured to cause the power storage device 311 to be charged with a predetermined capacity (hereinafter referred to as pre-state detection charging) before performing state detection. That is, when the state detection unit 410 requests the control unit 313 to charge the power storage device 311 before detecting the state, the control unit 313 starts the engine and operates the on-vehicle charger 314, thereby causing the power storage device 311 to have a predetermined capacity. Control to allow charging. Alternatively, maintenance personnel or the like can perform charging before detecting the state of the power storage device 311. In this case, a maintenance person or the like connects the battery charger 311 to the external charger 320 and charges it before detecting the state. The state detection unit 410 is configured to detect the state of the power storage device 311 after the pre-state detection charging by the in-vehicle charger 314 or the external charger 320 is performed. A communication bus such as LIN (Local Interconnect Network) or CAN (Controller Area Network) is used as a communication unit between the state detection unit 410 and the signal input unit 401, the output display unit 402, the measurement unit 403, and the control unit 313. Can be used.

  Next, the outline of the state detection method of this reference example will be described using the flowchart shown in FIG. When performing the state detection of the power storage device 311 using the state detection device 400 of the present reference example, first, a state detection mode start signal is input to the state detection unit 410 (step S301). Thereby, the state detection unit 410 determines whether a predetermined state detection permission condition is satisfied (step S302). This state detection permission condition includes that at least the power storage device 311 stops charging / discharging.

  If it is determined in step S302 that the state detection permission condition is satisfied, the state detection mode is set to ON in step S303, and the power storage device 311 is charged before state detection in the next step S304. When the pre-state detection charging is completed, the state detection unit 410 detects the state of the power storage device 311 (step S305). As the state detection, for example, the remaining capacity SOC of the power storage device 311 can be estimated, and the discharge capacity of the power storage device 311 can be determined based on this. When the discharge capability of the power storage device 311 is determined by the state detection process, the result is output to the output display unit 402 and notified to the user, maintenance personnel, and the like (step S306). On the other hand, if it is determined in step S302 that the condition detection permission condition is not satisfied, the process ends without performing the processes in steps S303 to S306.

  Below, the state detection method of the electrical storage device 311 performed in the state detection part 410 is demonstrated. Since the transient change after stopping charging / discharging of the battery 311 includes reaction processes with different speeds, in order to determine the discharging capability of the battery 311 after stopping charging / discharging with high accuracy, the state change for each reaction speed. It is better to detect the state using a method that can evaluate the above. For example, the battery voltage change ΔV (t) after stopping charging / discharging is expressed by the following equation using a function (hereinafter referred to as a relaxation function) F (t) consisting of m polynomials depending on the difference in reaction rate. Can be expressed as

ΔV (t) = F (t)
= F ₁ (t) + f ₂ (t) +... F _m (t) = Σf _i (t) (2-1)
Here, the voltage change amount ΔV (t) includes the voltage measurement value V _mes (t) when the time t has elapsed since the completion of the pre-state detection charging, and a sufficient time (for example, 20 hours) after the charge / discharge stop. It represents the difference from the stable voltage at the time of stopping (hereinafter referred to as OCV _{20 hr} ) when it becomes substantially constant after elapse.
_{ΔV (t) = V mes (} t) -OCV 20hr (2-2)
In this reference example, state detection is performed using the above equation.

In the above relaxation function F (t), each term f _i (t) represents the contribution to the voltage change in the relaxation process with different reaction speeds of the battery 311. Hereinafter, the relaxation function for each reaction speed f _i (t ). Each f _i (t) is a function depending on the deterioration degree SOH, which is the state quantity of the battery 311, the remaining capacity SOC (ion concentration), and the temperature T. Calculating a [Delta] V (t) from the voltage measured value V _mes (t), to optimize at the calculated [Delta] V (t) from equation (2-1) a voltage measured value V _mes (t), for each reaction rate A relaxation function f _i (t) can be determined.

In the state detection method of this reference example, the voltage measurement value of the power storage device 311 is input at a predetermined cycle after the completion of the pre-state detection charging, and the relaxation function F (t) is optimized every time the voltage measurement value is input. Have been updated. When the relaxation function for each reaction rate when optimized using the voltage measurement value measured for the nth time is f _i ⁿ (t), f _i ⁿ (t) can be expressed as the following equation.
f _i ⁿ (t) = f _i ^ref (t) * {SOC ⁿ / SOC ^ref }
* {SOH _i ⁿ / SOH _i ^ref } * G (T) (2-3)
Here, f _i ^ref (t), SOC ^ref , and SOH _i ^ref respectively represent a relaxation function for each reaction rate, a remaining capacity SOC, and a deterioration degree SOH for each reaction rate in a predetermined reference state, and G (T) Represents the dependence on the temperature T of the electricity storage device. The equation (2-3), it is possible to calculate the residual capacity SOC ⁿ and the reaction rate per degree of degradation SOH _i ⁿ is estimated using the n-th voltage measurement. The discharge capacity of the electricity storage device 311 can be determined from the SOC ⁿ . Further, the reaction rate per degree of degradation SOH _i ⁿ from degradation degree SOH obtained by integrating the total reaction rate, it is possible to determine the degree of deterioration of power storage device 311.

  In order to optimize the relaxation function F (t) shown in the equation (2-1) with high accuracy, there is a reproducibility so that the transient change at the time of state detection can always be regarded as the same or the same trend. The state is preferable. Therefore, in the state detection method of the power storage device 311 of this reference example, the charge / discharge state is shifted to a reproducible state as much as possible before the state detection, and then the state detection is performed. In order to shift the charge / discharge state before the start of state detection to a reproducible state as much as possible, in this reference example, charging of a predetermined capacity (charging before state detection) is performed in step S304 of FIG. State detection is performed by measuring changes and the like.

  As an appropriate state-precharging charge capacity for transferring the electricity storage device 311 to a reproducible state, out of the electrophoresis of the electrolyte accompanying charging / discharging during vehicle operation, the influence of electrophoresis accompanying discharge is negated. It is preferable that the capacity is sufficient. As a result, the effect of the pre-state detection charging due to the discharge during vehicle operation can be reduced, and the voltage change associated with the charge polarization can be measured during the state detection. In the following, an appropriate capacity for charging before state detection will be described for a storage battery of an automobile.

  In actual driving of a car, the charge / discharge capacity changes arbitrarily and frequently, so it is conceivable to measure and accumulate the charge / discharge capacity during driving and determine the charge capacity before state detection based on this. It is done. However, in the method of integrating the charge / discharge capacity during traveling, a charge / discharge capacity with high accuracy cannot always be obtained, and it is difficult to determine an appropriate charge capacity when shifting to the state detection mode. In addition, if the system shifts to the state detection mode after a large amount of discharge has been performed, such as when idling stops are repeatedly performed, the required capacity for charging before state detection may increase. There is a problem that the time required for the process becomes longer.

  Therefore, in the state detection method of this reference example, instead of determining the charge capacity before state detection using the accumulated charge and discharge during traveling, the transient change during charging is examined in advance for each target power storage device. Based on this, the pre-state detection charge capacity is determined in advance. As an example, in the case of a vehicle equipped with the Furukawa Battery 55B24 (36 [Ah]), when the vehicle travels normally for about 1 to 2 hours, the charge / discharge capacity (ΔSOC) of the battery during traveling (ΔSOC) ( (Absolute value) is 0.5% or less.

  Therefore, by setting the capacity for charging before state detection to a capacity sufficiently larger than the charge / discharge amount at the time of traveling, the influence of charging / discharging before shifting to the state detection mode can be sufficiently reduced. As a result, in the state detection method of this reference example, since the storage battery state when performing state detection is governed by a transient change caused by charging before state detection, it can be said that the state is a reproducible transient state. . It will be described with reference to FIG. 31 how the transient change of the storage battery after charging before state detection changes depending on the charge / discharge capacity at the time of the previous run. FIG. 31 shows changes in the current and voltage of the storage battery at the time of detection of the state after operation to stop, and how the transient change changes depending on the magnitude relationship between the charge / discharge capacity during operation and the charge capacity before detection of the state. It is the graph which showed typically what to do. Here, the charging capacity before state detection is set to 5% of the rated capacity.

  FIG. 31A shows changes in current and voltage when the pre-state detection charge capacity is larger than the charge / discharge capacity during operation, and FIG. 31B shows the charge / discharge capacity and state detection during operation. FIG. 31 (c) shows changes in current and voltage when the charge / discharge capacity during operation is larger than the charge capacity before state detection. In the case where the pre-state detection charge capacity shown in FIG. 31A is larger, the charge / discharge capacity during operation is set to 1% or less. In this case, the influence of charging / discharging during operation is reduced by the pre-state detection charging, and as a result, the voltage change after the pre-state detection charging monotonously decreases and converges to a stable voltage.

  In addition, assuming that the charge / discharge capacity during operation and the charge capacity before state detection shown in FIG. 31 (b) are approximately the same, the charge / discharge capacity during operation is set to 1% to 5%. Also in this case, the influence of charging / discharging during operation can be reduced by the pre-state detection charging, and the voltage change after the pre-state detection charging decreases monotonously to a stable voltage as in FIG. Shows a tendency to converge. Further, when the charge / discharge capacity during operation shown in FIG. 31 (c) is larger than the pre-state detection charge capacity, the voltage tends to increase monotonously after the completion of the pre-state detection charge, as shown in FIG. 31 (a). , (B) shows a completely different tendency.

  Charging / discharging capacity during vehicle travel is usually about 1% or less, and when the pre-state detection charge capacity is 5%, the effect of charge / discharge polarization due to charge / discharge during normal vehicle travel is sufficiently reduced. can do. As a result, in the state detection after performing the pre-state detection charging, the discharge capability is detected based on the transient change shown in FIGS. 31A and 31B due to the 5% capacity charging. By using a function form that can optimally approximate a transient change caused by charging of 5% capacity as the relaxation function F (t) in Expression (2-1), state detection using the relaxation function F (t) is enhanced. It becomes possible to carry out with accuracy.

  On the other hand, when the charge / discharge capacity during operation as shown in FIG. 31 (c) is larger than the charge capacity before state detection, a voltage lower than the stable voltage is measured. It is possible to notify a user or the like that the ability is reduced. As an example in which the discharge capacity during operation increases, there is a case where the operation is stopped after idling stop is repeatedly performed in a short time. The voltage measurement value becomes lower than the stable voltage, in addition to the case where the amount of discharge during operation is particularly large, the deterioration of the storage battery 11 or the case where it has been left for a long time. Even in such a case, it is possible to detect a decrease in capacity (insufficient capacity) or an increase in deterioration by the state detection method of this reference example.

  In addition, the capacity for charging before state detection can be set to a different value depending on what type of driving is targeted for normal vehicle driving, and also considers the size, characteristics, etc. of the storage battery installed in the vehicle. It is better to decide. For example, in the case of setting the capacity for state pre-charge detection for discharge due to idling stop, it is preferable to set a charge capacity that is equal to or greater than the capacity discharged at idling stop. By performing charging that is larger than the discharge capacity during operation, state detection can be performed in a transient state in which the voltage at the time of state detection monotonously decreases as shown in FIGS. 31 (a) and 31 (b). it can.

  The state detection method of the present reference example, which has been outlined with reference to FIG. 29, will be described in further detail with reference to FIGS. FIG. 32 is a flowchart for explaining processing from when the state detection mode is requested to when charging before state detection ends. FIG. 32A shows the flow of processing when a driver or the like inputs a state detection mode start signal from the signal input means 401, and FIG. 32B shows a state detection mode switch by a maintenance person or the like. The flow of processing when 411 is turned on is shown.

  In either case of inputting the state detection mode start signal from the signal input means 401 or turning on the state detection mode switch 411, there is a possibility that the signal is input by an erroneous operation. Therefore, FIG. 32A describes the flow of processing when configured to prevent erroneous operations, and FIG. 32B describes the flow of processing when no erroneous operations are taken into consideration. However, FIG. 32 (b) can be configured to prevent erroneous operation as in FIG. 32 (a), and erroneous operation prevention processing can be omitted in FIG. 32 (a).

  In FIG. 32A, when a state detection mode start signal is input from the signal input means 401 (step S311), this signal is output to the state detection unit 410. When receiving the state detection mode start signal, the state detection unit 410 displays a confirmation message on the output display unit 402 to confirm that the state detection is requested (step S312). Based on the confirmation message, for example, when a confirmation signal is input from the signal input means 401 (step S313), it is next determined whether a predetermined state detection permission condition is satisfied (step S314).

  As said condition detection permission conditions, it is requested | required that the storage battery 311 is not charging / discharging at least. As a method for determining that the storage battery 311 is not charging / discharging, for example, it is confirmed that the vehicle 310 is in a stopped state (the key switch is in the OFF position). Further, whether the state detection unit 410 and the peripheral device can communicate with each other, whether the measurement value from the measurement unit 403 indicates a value within the normal range, or can start the engine and operate the in-vehicle charger 314 normally. If any of them is abnormal, the state detection permission condition may not be established.

  If the result of determination in step S314 is that the condition detection permission condition is satisfied, the condition detection mode is set to ON in step S315. At this time, the output display unit 402 may display that the state detection mode is turned on. In step S316, the on-vehicle charger 314 is used to cause the storage battery 311 to start pre-state detection charging. The pre-state detection charging using the in-vehicle charger 314 is performed by the state detection unit 410 requesting the control unit 313 to charge a predetermined capacity, and the control unit 313 starts the engine and operates the in-vehicle charger 314. .

  On the other hand, if the state detection permission condition is not satisfied in the determination in step S314, the process ends without performing the processes in steps S315 and S316. At this time, which of the state detection permission conditions is not satisfied may be displayed on the output display unit 402.

  Next, the flow of processing for starting state detection by turning on the state detection mode switch 411 will be described with reference to FIG. When a maintenance worker or the like turns on the state detection mode switch 411 (step S321), a state detection mode start signal is output to the state detection unit 410. When the state detection unit 410 receives the state detection mode start signal, it next determines whether a predetermined state detection permission condition is satisfied (step S322). The condition detection permission condition can be the same as in the case of FIG.

  If the state detection permission condition is satisfied as a result of the determination in step S322, the state detection mode is set to ON in step S323, and in step S324, the state is detected before the state is detected for the storage battery 311 using the external charger 320. Start charging. Charging by the external charger 320 is performed by maintenance personnel or the like. Therefore, in step S324, it is preferable to display a charge start request message on the output display means 402, so that a maintenance staff or the like confirms this and performs charging. When charging of a predetermined capacity is completed, maintenance personnel or the like operate the state detection mode switch 411, or input a signal notifying that pre-state detection charging has ended from the signal input unit 401. Good.

  On the other hand, if the state detection permission condition is not satisfied in the determination in step S322, the process ends without performing the processes in steps S323 and S324. At this time, which of the state detection permission conditions is not satisfied may be displayed on the output display unit 402.

  Next, the flow of processing when the state detection mode is established will be described with reference to FIG. The process shown in FIG. 33 is executed at a predetermined cycle. First, in step S331, it is determined whether the state detection mode is on. As a result, if the state detection mode is on, the process proceeds to step S332, and if the state detection mode is off, the process ends without performing the following processing. In the next step S332, it is determined whether the condition detection permission condition is satisfied. The confirmation of the condition detection permission condition is always performed during the condition detection mode period. As a result, if the state detection permission condition is satisfied, the process proceeds to the next step S333. If the state detection permission condition is not satisfied, the process proceeds to step S339. In this case, which of the state detection permission conditions is not satisfied may be displayed on the output display unit 402.

  In step S333, it is determined whether or not charging before state detection is completed. When the pre-state detection charging is performed using the in-vehicle charger 314, it can be determined by checking whether the charging is completed with respect to the control unit 313. Alternatively, the determination can be made based on the elapsed time from the start of charging. Further, when the pre-state detection charging is performed using the external charger 320, the determination is made by inputting a charge end signal from the state detection mode switch 411 or the signal input unit 401. If the result of determination in step S333 is that pre-state detection charging has been completed, processing proceeds to the next step S334. On the other hand, if it is determined that the pre-state detection charging has not ended, the processing ends without performing the following processing.

In step S334, the current voltage measurement value V _mes (t) is input using the measuring unit 403. In step S335, the relaxation function F (t) is input using the voltage measurement value V _mes (t) input so far. To optimize. In the next step S336, the discharge capacity of the storage battery 311 is estimated using the optimized F (t). As the discharge capacity, for example, the estimated value of the stable voltage OCV _20hr at the time of stoppage is updated from the equations (2-1) and (2-2), and the SOC obtained from the relationship between the OCV _20hr and the SOC as shown in FIG. Can be used. In step S337, the SOC estimated in this way is temporarily stored in a predetermined storage unit.

  In step S338, it is determined whether the elapsed time t from the start of state detection has reached a predetermined time. If the elapsed time t has reached the predetermined time, the process proceeds to step S339. On the other hand, if the elapsed time t has not reached the predetermined time, the process ends without performing the following processing. In step S339, the discharge capability temporarily stored in step S337 is read, and when this is equal to or greater than a predetermined threshold, it is determined that the discharge capability is normal, and when it is less than the predetermined threshold, it is determined that the discharge capability is abnormal. In step S340, the result of determining the discharge capability is output to the output display means 402. Further, in step S341, the state detection mode is turned off and the process is terminated.

  Another reference example of the state detection method of the electricity storage device will be described below with reference to the flowchart shown in FIG. In the state detection method of this reference example, state detection by pulse discharge (step S351) and state detection by impedance measurement (step S352) are performed before performing state detection of the storage battery 311 in the state detection mode. The state detection by pulse discharge measures the current and voltage when the storage battery 311 is pulse-discharged, and detects the discharge capacity and the deterioration state of the storage battery 311 based on the measured current and voltage. In the state detection by impedance measurement, the internal impedance of the storage battery 311 is estimated from measured values of current and voltage, and the deterioration state of the storage battery 311 is detected based on this.

  The state detection method by the state detection mode of this reference example may be performed independently as in the fourth reference example, or the state detection by pulse discharge and the state detection by impedance measurement as in this reference example. It can also be done in combination. In addition, it is not always necessary to combine state detection by pulse discharge and state detection by impedance measurement, and one of state detection by pulse discharge and state detection by impedance measurement is combined with state detection by state detection mode. Is also possible.

  In the above description, the case where the state detection is performed immediately after the charge / discharge of the storage battery 311 is stopped has been described. However, the present invention is not limited to this, and for example, the state detection is performed even when the charge / discharge of the storage battery 311 is stopped for a long time. Can do. For example, the discharge capability of the storage battery 311 can be confirmed by executing the state detection mode at a frequency of about once a month. At the same time, recovery charging (5% charging) of the storage battery 311 can be performed safely and efficiently even when parking for a long time by charging before state detection in the state detection mode.

  In this reference example, as a method of performing pre-state detection charging, in response to a request from the state detection unit 410, the control unit 313 starts the engine and operates the in-vehicle charger 314 to charge the storage battery 311. However, instead of this, a state detection mode start signal may be input immediately before the driver finishes traveling and stops the engine. In this case, for example, even if the key switch is turned off, the on-vehicle charger 314 immediately performs the pre-state detection charging without stopping the engine, and when the charging is completed, the engine is automatically stopped.

  In the above reference example, the case where it is detected whether the discharge capability is secured as the state detection of the power storage device has been described. However, the present invention is not limited to this, and it is also easy to determine deterioration of SOH or the like. is there. Since the relaxation function F (t) also has dependency on the SOH, an equation for calculating the SOH can be derived from the relaxation function F (t). By using such an expression, it is possible to estimate the SOH and determine the deterioration state of the electricity storage device.

  As described above, according to the state detection method and state detection device of the power storage device of the present reference example, the state of the power storage device is a reproducible transient change by charging a predetermined capacity before performing the state detection. Has moved to. As a result, it is possible to perform state detection in a reproducible transient state that can be regarded as equivalent or have the same tendency, and it is possible to detect the state of the power storage device with high accuracy. As a result, insufficient charging or failure of the power storage device can be detected at an early stage, and the reliability as a backup of vehicle operation or auxiliary equipment can be improved. Furthermore, the charging before the state detection can prevent a large capacity shortage and reduce the deterioration of the power storage device, thereby realizing stable operation of the system and extending the life of the power storage device.

  Note that the description in the present embodiment shows an example of the state detection method of the power storage device according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the power storage device state detection method in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1: Vehicle 2: Load 10: Storage battery 11: Charging means 12: Control means 20: Voltage measuring means 21: Current measuring means 22: Temperature measuring means 100: State detection device 110: State detection part 120: Storage part 130: State output means

Claims (7)

It is a state detection method of an electricity storage device that determines the discharge capability during charging / discharging and stopping charging / discharging for each predetermined cycle,
The measured voltage value of the electricity storage device measured immediately after the last charge / discharge stop is stored in a predetermined storage unit as the charge / discharge stop voltage V_end,
Read the charge / discharge stop voltage V_end from the storage unit,
The current voltage change amount ΔVa_n is calculated by subtracting the current voltage measurement value V_now (assuming the number of cycles is n) from the charge / discharge stop voltage V_end,
A discharge capacity correction amount COD_SOH_n of the power storage device is calculated using a discharge capacity correction function F (SOH, ΔVa_n) created in advance from the deterioration degree SOH of the power storage device and the voltage change amount ΔVa_n.
The current discharge capacity COD_now of the electricity storage device is expressed by the following equation: COD_now = V_now−COD_SOH_n
Calculated by
It is determined that the discharge capacity of the power storage device is maintained when the discharge capacity COD_now is greater than a predetermined threshold value COD_Th. The deterioration degree SOH is a deterioration degree SOH_n1 calculated when the number of cycles n1 (n1 ≦ n) during the charge / discharge stop closest to the present time,
The discharge capacity correction amount COD_SOH_n reads the discharge capacity correction function F (SOH_n1, x) (x is a variable) corresponding to the deterioration degree SOH_n1 from the storage unit, and substitutes the voltage change amount ΔVa_n for the variable x. The state detection method for an electricity storage device according to claim 1, wherein The discharge capacity correction function F (SOH, ΔVa) is a response function relaxation function fi (i = 1) of 2 or more (assumed to be m) prepared in advance corresponding to the speed of transient change in the electric storage device. ~ M) linear combination,
During the charge / discharge stop of the electricity storage device, the voltage measurement value is stored in the storage unit,
The said reaction rate relaxation function fi is optimized using the said voltage measurement value preserve | saved at the said memory | storage part according to the elapsed time from the said charging / discharging stop. The Claim 1 or 2 characterized by the above-mentioned. The state detection method of the electrical storage device of description. When the electric storage device is in a charge / discharge stop and the elapsed time from the charge / discharge stop exceeds a predetermined time (first relaxation time),
Optimize the relaxation rate fi for each reaction rate corresponding to a fast transient using the measured voltage value stored in the storage unit,
A degradation degree SOH_fast_n that depends on a fast transient change is calculated using the optimized relaxation function fi for each reaction rate,
The current degree of deterioration using a predetermined function G based on the degree of deterioration SOH_slow_n2 and the degree of deterioration SOH_fast_n depending on the slow transient change calculated when the number of cycles n2 (n2 ≦ n) closest to the current charge / discharge is stopped SOH_n is expressed by the following formula: SOH_n = G (SOH_fast_n, SOH_slow_n2)
Calculated by
The discharge capacity correction amount COD_SOH_n is calculated by reading the discharge capacity correction function F (SOH_n, x) corresponding to the deterioration degree SOH_n from the storage unit and substituting the voltage change amount ΔVa_n into the variable x. The state detection method of the electrical storage device of Claim 3 characterized by these. When the electric storage device is in a charge / discharge stop and an elapsed time from the charge / discharge stop exceeds a predetermined second relaxation time longer than the first relaxation time,
Further, the relaxation function fi for each reaction rate depending on a slow transient change is optimized using the voltage measurement value stored in the storage unit,
A degradation degree SOH_slow_n depending on a slow transient change is calculated using the optimized relaxation function fi for each reaction rate,
Based on the calculated deterioration degree SOH_fast_n depending on the fast transient change and deterioration degree SOH_slow_n depending on the slow transient change, the current deterioration degree SOH_n is expressed by the following equation using the function G: SOH_n = G (SOH_fast_n, SOH_slow_n)
The state detection method of the electrical storage device according to claim 4, wherein Immediately after stopping charging / discharging, the power storage device is charged to a predetermined capacity (charging before state detection), and the voltage measurement value measured immediately after the end of charging before state detection is stored in the storage unit as the voltage V_end at the time of stopping charging / discharging. The state detection method of the electrical storage device of any one of Claims 1 thru | or 5 characterized by the above-mentioned. A state detection device for an electricity storage device that determines discharge capability during charge / discharge and charge / discharge stop for each predetermined cycle,
A storage unit for storing a voltage measurement value of the power storage device;
A state detection unit that reads data stored in the storage unit and determines the discharge capacity of the power storage device for each cycle;
A state output unit that inputs a determination result from the state detection unit and outputs the determination result to the outside, and
The storage unit stores the measured voltage value of the electricity storage device measured immediately after the last charge / discharge stop as a charge / discharge stop voltage V_end,
The state detection unit
Read the charge / discharge stop voltage V_end from the storage unit,
The current voltage change amount ΔVa_n is calculated by subtracting the current voltage measurement value V_now (assuming the number of cycles is n) from the charge / discharge stop voltage V_end,
A discharge capacity correction amount COD_SOH_n of the power storage device is calculated using a discharge capacity correction function F (SOH, ΔVa_n) created in advance from the deterioration degree SOH of the power storage device and the voltage change amount ΔVa_n.
The current discharge capacity COD_now of the electricity storage device is expressed by the following equation: COD_ow = V_ow−COD_SOH_n
Calculated by
It is determined that the discharge capacity of the power storage device is maintained when the discharge capacity COD_ow is greater than a predetermined threshold value COD_h.

Images