JP2023157422A - battery system - Google Patents

Abstract

To provide a battery system with a battery pack capable of improving the accuracy of diagnosis while labor-saving for the diagnosis by diagnosing the battery pack at the right time.SOLUTION: A restraint load estimation unit 55b estimates an estimated restraint load Le by a battery pack restraint band. When the estimated restraint load Le is greater than or equal to a predetermined value X, the diagnostic mode processing unit 55c performs a diagnosis of a restraint load Ls of the restraint band. The restraint load Ls is calculated based on a first battery voltage V1 when charging/discharging is not made for a first predetermined time T1 with SOC of a first predetermined value α or lower, a second battery voltage V2 when charge/discharge is not made for a second predetermined time T2 with the SOC at or above a second predetermined value β, and charge current integrated value ΣI when charging from the first predetermined value α to the second predetermined value β.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a battery system, and particularly to a battery system including an assembled battery.

Japanese Patent Application Publication No. 2020-119820 (Patent Document 1) discloses that in an assembled battery in which a plurality of stacked cells (single cells) are restrained by a restraining member, the degree of deterioration, temperature, and SOC (State of Charge) of the assembled battery are determined. Fatigue failure of the restraining member is determined by estimating the restraining load of the restraining member.

JP2020-119820A

In Patent Document 1, fatigue failure of the restraint member is diagnosed by estimating the restraint load of the restraint member. The restraint load is estimated using the degree of deterioration, temperature, and SOC estimated from the capacity retention rate. Therefore, in order to accurately estimate the restraint load, it is required to calculate the capacity retention rate with high accuracy.

In order to obtain a highly accurate capacity maintenance rate, it is preferable to perform suitable charge/discharge control (hereinafter also referred to as diagnostic mode charge/discharge control) in order to calculate the capacity maintenance rate. However, the charging and discharging control for diagnostic mode is different from the charging and discharging control when the assembled battery is used. For this reason, frequently executing charge/discharge control for diagnostic mode results in waste of power and time.

An object of the present disclosure is to improve diagnostic accuracy while saving labor in diagnosis by diagnosing the assembled battery at appropriate timing in a battery system including assembled batteries.

The battery system of the present disclosure includes an assembled battery in which a plurality of stacked unit cells are restrained by a restraining member, and a control device that controls the assembled battery. The control device includes a restraint load estimation section that estimates a restraint load due to the restraint member, and a diagnosis mode processing section that performs diagnosis of the assembled battery when the restraint load estimated by the restraint load estimation section is equal to or greater than a predetermined value.

When a cell is used for a long period of time, the electrode expands and gas is generated within the cell, causing the cell to expand. Further, when the SOC of the unit cell is large, the electrode expands and the unit cell expands. When the cell expands, the restraining load on the restraint member increases, and the mechanical load (load, pressure, stress, etc.) applied to the restraint member and the cell is large, and the harsh environment can lead to various malfunctions of the assembled battery. expensive.

According to this configuration, when the restraint load estimated by the restraint load estimation section of the control device is equal to or greater than a predetermined value, the diagnosis mode processing section of the control device executes the diagnosis of the assembled battery. Therefore, the assembled battery is diagnosed when the restraining load of the restraining member is large and there is a high possibility that various malfunctions of the assembled battery will occur, so the assembled battery is diagnosed at an appropriate timing and labor-saving in diagnosis is achieved. It will be done. Furthermore, since the assembled battery is diagnosed in a harsh environment, it is expected that the accuracy of diagnosis will improve.

Preferably, the diagnosis executed by the diagnostic mode processing section is a diagnosis of restraint load, and the diagnostic mode processing section discharges the assembled battery so that the SOC of the assembled battery becomes equal to or less than a first predetermined value, and a first voltage acquisition unit that acquires a first battery voltage that is the voltage of the assembled battery when charging and discharging of the assembled battery is stopped for a first predetermined time in a state where the assembled battery is below a predetermined value; A charging current integrating unit that charges the battery and integrates the charging current; and a charging current integrating unit that charges the battery and integrates the charging current; and a charging current integrating unit that charges the battery when the SOC reaches or exceeds a second predetermined value, and stops charging the battery when charging and discharging the assembled battery is stopped for a second predetermined period of time; A restraint load is calculated based on a second voltage acquisition unit that acquires a second battery voltage, a charging current integrated value calculated by a charging current integration unit, the first battery voltage, and the second battery voltage. A restraint load calculation section may also be included.

According to this configuration, the diagnosis mode processing section executes the diagnosis of the restraint load. The first voltage acquisition section of the diagnostic mode processing section discharges the assembled battery so that the SOC of the assembled battery becomes equal to or less than a first predetermined value, and performs charging and discharging of the assembled battery in a state where the SOC becomes equal to or less than the first predetermined value. The first battery voltage, which is the voltage when the battery is stopped for one predetermined period of time, is acquired. After acquiring the first battery voltage, the charging current integration unit charges the assembled battery and integrates the charging current. When the SOC becomes equal to or higher than a second predetermined value, the second voltage acquisition unit stops charging and acquires a second battery voltage that is a voltage when charging and discharging of the assembled battery is stopped for a second predetermined period of time. The restraint load calculation unit calculates the restraint load based on the charging current integrated value, the first battery voltage, and the second battery voltage.

The diagnostic mode processing section performs charging/discharging control for the diagnostic mode in order to calculate the restraint load. Then, a restraint load is calculated from the charging current integrated value, the first battery voltage, and the second battery voltage during charge/discharge control for the diagnostic mode. Further, the first battery voltage is the voltage when charging and discharging of the assembled battery is stopped for a first predetermined time, and the second battery voltage is the voltage when charging and discharging of the assembled battery is stopped for a second predetermined time, This is the voltage after polarization is eliminated. Therefore, the restraint load can be calculated with high accuracy. In addition, when the restraint load estimated by the restraint load estimating section exceeds a predetermined value and a highly accurate restraint load is required, such as for predicting breakage of a restraint member, the diagnostic mode processing section performs charging/discharging control for the diagnostic mode. Since the restraint load is calculated by performing the following steps, it is possible to avoid wasting power and time.

Preferably, the first battery voltage and the second battery voltage are the voltages of a single battery, and the restraint load calculation unit calculates the battery voltage based on the charging current integrated value, the first battery voltage, and the second battery voltage. The full charge capacity of the battery may be estimated, and the restraint load may be calculated using the smallest value of the estimated full charge capacities.

According to this configuration, the full charge capacity of the cell is estimated and the restraint load is calculated using the smallest value of the estimated full charge capacity, so the restraint load is calculated based on the state of the cell that has deteriorated the most. The load is calculated. It is preferable that the restraint load calculated for predicting breakage of the restraint member is the restraint load under the most severe condition, and improvement in diagnostic accuracy of the assembled battery can be expected.

Preferably, the diagnosis executed by the diagnostic mode processing section is a diagnosis of a minute short circuit in the assembled battery, and the diagnostic mode processing section sets a threshold value that is smaller when the restraining load is large than when the restraining load is small. The battery may include a setting section and a micro short circuit detection section that determines that a micro short circuit has occurred when a parameter indicating a micro short circuit in the assembled battery is equal to or greater than a threshold value.

According to this configuration, the diagnostic mode processing section executes diagnosis of a minute short circuit in the assembled battery. The micro short circuit detection section of the diagnostic mode processing section determines that a micro short circuit has occurred when a parameter indicating a micro short circuit in the assembled battery is equal to or greater than a threshold value. The threshold value setting unit sets a smaller threshold value when the restraint load is large than when the restraint load is small, so that when the restraint load is large, the detection sensitivity of micro short circuits becomes high. Therefore, minute short circuits can be detected with high accuracy. In addition, in situations where the restraint load estimated by the restraint load estimator exceeds a predetermined value and a micro short circuit is likely to occur, the diagnostic mode processing unit diagnoses the micro short circuit. This enables labor-saving diagnosis.

According to the present disclosure, in a battery system including an assembled battery, by diagnosing the assembled battery at an appropriate timing, it is possible to expect an improvement in the accuracy of the diagnosis while saving labor in the diagnosis.

FIG. 1 is a diagram illustrating a schematic configuration of a power system including a battery system according to an embodiment. FIG. 1 is a perspective view schematically showing the structure of an assembled battery according to the present embodiment. FIG. 2 is a diagram illustrating functional blocks configured in a control device in this embodiment. 7 is a flowchart illustrating an example of processing executed by the control device in the present embodiment. FIG. 7 is a diagram illustrating functional blocks configured in a control device in a second embodiment. 7 is a flowchart illustrating an example of processing executed by the control device in Embodiment 2. FIG. It is a figure which shows the structure of the electric vehicle equipped with the battery system in a modification.

Embodiments of the present disclosure will be described in detail below with reference to the drawings. In the embodiments described below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a diagram showing a schematic configuration of a power system including a battery system according to the present embodiment. As shown in FIG. 1, the power system 1 includes a house 10, a power grid (power system) 20, a distribution transformer (pole transformer) 30, a smart meter 40, and a battery system 50.

The power grid 20 is a power system consisting of power plants, power transmission lines, high-voltage substations, etc., and is managed by a power retailer or the like. The electric power of the power grid 20 that has been stepped down to a voltage of, for example, 6.6 kV by the distribution substation is stepped down to, for example, single-phase three-wire 100V/200V by the pole transformer 30, and then passed through the smart meter 40. It is connected to the home power line 4. The smart meter 40 is an electronic electricity meter with a communication function, and measures the amount of electricity exchanged between the power grid 20 and the house 10 during a predetermined measurement period (for example, 30 minutes), For example, every 60 minutes), the measured power amount is transmitted to a server under the jurisdiction of the power retailer.

In the house 10 connected to the power grid 20 via the smart meter 40, for example, power conditioner (PCS) 12, solar power generation device 13, heat pump Various electric devices (household loads) such as a water heater 14, a refrigerator 15, and an air conditioner (cooling/heating device) 16 are connected using in-house power lines. Further, a battery system 50 is connected to the distribution board 11 via an in-house power line. Thereby, the power supplied from the power grid 20 can be consumed, or the power generated by the solar power generation device 13 or the power discharged from the battery system 50 can be supplied to the power grid 20 (reverse power flow). The power generated by the solar power generation device 13 is consumed by the household load and is stored in the battery system 50. Furthermore, the power discharged from the battery system 50 is consumed by household loads.

The house 10 is provided with a HEMS controller 60. The HEMS controller 60 is configured to be able to communicate with each electrical device such as the HEMS-compatible distribution board 11, PCS 12, refrigerator 15, air-conditioning device 16, and the battery system 50. The HEMS controller 60 acquires information on each electrical device and controls the operation of each electrical device.

Battery system 50 includes a battery 51, a monitoring unit 52, a charger/discharger 53, and a control device 55. The battery 51 is composed of a battery pack in which a plurality of single cells are stacked.

FIG. 2 is a perspective view schematically showing the structure of the assembled battery according to this embodiment. The assembled battery 510 includes a plurality of cells (single cells) 81, a plurality of resin frames 82, a pair of end plates 83, and a pair of restraint bands 84. In the assembled battery 510, a stacked body is formed by stacking a plurality of cells 81 and a plurality of resin frames 82.

Each of the plurality of cells 81 is a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The number of cells included in assembled battery 510 is not particularly limited. The configuration of each cell 81 is common, and the stacked cells 81 are electrically connected in series.

Each of the plurality of resin frames 82 is arranged between two adjacent cells 81 in the stacking direction. A pair of end plates 83 are arranged at one end and the other end of the laminate in the stacking direction. The end plates 83 are arranged to sandwich the laminate from both sides in the stacking direction.

A plurality of restraint bands (restraint members) 84 are arranged on the upper surface and the lower surface of the resin frame 82. The restraint band 84 restrains the pair of end plates 83 with the stack sandwiched therebetween.

The battery 51 may be a battery pack in which a plurality of assembled batteries 510 are connected in series or in parallel, or may be a battery module consisting of one assembled battery 510.

Referring to FIG. 1, the monitoring unit 52 includes a voltage sensor, a current sensor, and a temperature sensor (not shown). The voltage sensor detects the voltage Vb of the assembled battery 510 (more specifically, the voltage of each cell 81). The current sensor detects the current Ib input to and output from the assembled battery 510. The temperature sensor detects the temperature Tb of the assembled battery 510. Each sensor outputs a signal indicating its detection or measurement result to the control device 55.

The charger/discharger 53 charges and discharges the battery 51 (battery assembly 510). The charger/discharger 53 is connected to the distribution board 11 and the PCS 12 via an in-home power line, and includes a relay that switches connection/cutoff of a power path and a power conversion circuit (for example, a bidirectional converter). The charger/discharger 53 charges the assembled battery 510 using the power of the power grid 20 and the power generated by the solar power generation device 13 (charging mode). The charger/discharger 53 supplies power to the household load or the power grid 20 by discharging the power stored in the assembled battery 510 (discharge mode). The charger/discharger 53 is controlled by a control device 55.

The control device 55 is configured by, for example, an electronic control unit (ECU), and is capable of communicating with the HEMS controller 60. The control device 55 controls the charger/discharger 53 to control charging and discharging of the assembled battery 510 and diagnoses the assembled battery 510.

As shown in FIG. 2, the assembled battery 510 is restrained by a restraint band (restraint member) 84. When the cell (single cell) 81 is used for a long period of time, the electrode expands and gas is generated within the cell 81, causing the cell 81 to expand. Further, when the SOC of the cell 81 is large, the electrode expands and the cell 81 expands. When the cell 81 expands, the restraint load on the restraint band 84 increases, and the mechanical load (load, pressure, stress, etc.) applied to the restraint band 84 and the cell 81 increases, so that, for example, there is a possibility that the restraint band 84 will break. be.

In this embodiment, by diagnosing the restraint load of the restraint band 84, it is possible to predict the breakage of the restraint band 84, etc.

FIG. 3 is a diagram illustrating functional blocks configured in the control device 55 in this embodiment. The SOC calculation unit 55a calculates the SOC of the assembled battery 510. The method for calculating the SOC may be a known coulomb counting method that integrates charging and discharging currents, or may be calculated from SOC-OCV (Open Circuit Voltage) characteristics. Further, it may be a combination of the SOC-OCV characteristic and the Coulomb counting method.

The restraint load estimation unit 55b estimates the restraint load (estimated restraint load Le) of the restraint band 84. In this embodiment, the estimation is based on the usage period of the battery pack 510. When the cell (single cell) 81 deteriorates as the assembled battery 510 is used, the electrode expands and gas is generated within the cell 81, causing the cell 81 to expand and the restraining load to increase. The relationship between the usage period of the assembled battery 510 and the restraining load is determined in advance through experiments, simulations, and the like. When the assembled battery 510 is new, an initial restraint load (design restraint load) is set in the restraint load estimator 55b. Then, the restraint load estimation unit 55b estimates the estimated restraint load Le so that the restraint load increases as the usage period of the assembled battery 510 passes.

The diagnosis mode processing unit 55c executes diagnosis of the restraint load (restraint load Ls) of the restraint band 84 when the estimated restraint load Le becomes equal to or greater than the predetermined value X. The diagnostic mode processing unit 55c performs charge/discharge control for the diagnostic mode and calculates the restraint load Ls of the restraint band 84.

The diagnostic mode processing section 55c includes a first voltage acquisition section 551, a charging current integration section 552, a second voltage acquisition section 553, and a restraint load calculation section 554. The first voltage acquisition unit 551 discharges the battery pack 510 until the SOC of the battery pack 510 becomes equal to or less than the first predetermined value α. The first predetermined value α may be, for example, 5%. The charger/discharger 53 is set to the discharge mode, and the assembled battery 510 is discharged. The power discharged from the assembled battery 510 is consumed by, for example, a household load. When the SOC of the battery pack 510 drops to the first predetermined value α, the first voltage acquisition unit 551 stops discharging the battery pack 510 and suspends charging and discharging. Then, the first voltage acquisition unit 551 acquires the first battery voltage V1, which is the voltage Vb when the first predetermined time T1 has elapsed since the discharging of the assembled battery 510 has stopped (charging and discharging have stopped). In this embodiment, the first battery voltage V1 is a voltage for each cell 81. Note that the first predetermined time T1 may be, for example, one hour, and the first battery voltage V1 is the voltage Vb when polarization is eliminated.

After the first voltage acquisition unit 551 acquires the first battery voltage V1, the charging current integration unit 552 charges the assembled battery 510 and integrates the current Ib (charging current) to calculate the charging current integrated value ΣI. . Charging current integration unit 552 sets charger/discharger 53 to charging mode and charges assembled battery 510. The charging power may be the power of the power grid 20 or the power generated by the solar power generation device 13. Charging current integration section 552 calculates charging current integrated value ΣI by integrating current Ib output from monitoring unit 52. The charging current integrated value ΣI is a time integral value of the current Ib, and corresponds to the amount of change in the capacity [Ah] of the assembled battery 510 (cell 81).

When the SOC of the assembled battery 510 increases to the second predetermined value β due to charging and the SOC becomes equal to or higher than the second predetermined value β, the second voltage acquisition unit 553 stops charging and suspends charging and discharging. The second predetermined value β may be, for example, 85%. The second voltage acquisition unit 553 acquires the second battery voltage V2, which is the voltage Vb when the battery pack 510 is in a stopped charging state (charging/discharging paused state) after a second predetermined time T2 has elapsed. In this embodiment, the second battery voltage V2 is a voltage for each cell 81. Note that the second predetermined time T2 may be, for example, one hour, and the second battery voltage V2 is the voltage Vb when polarization is eliminated. Charging current integration section 552 stops integrating current Ib (charging current) when charging stops.

The restraint load calculation unit 554 calculates the restraint load Ls based on the integrated current value ΣI, the first battery voltage V1, and the second battery voltage V2. In this embodiment, the full charge capacity FC of each cell 81 is estimated from the integrated current value ΣI, the first battery voltage V1, and the second battery voltage V2. Then, the restraint load Ls is determined using the estimated minimum value FCmin of the full charge capacity FC. For example, calculate the SOC change amount ΔS (=SOC2-SOC1), which is the difference between SOC1, which is the SOC of the cell 81 calculated from the first battery voltage V1, and SOC2, which is the SOC of the cell 81 calculated from the second battery voltage V2. . Then, the full charge capacity FC of the cell 81 is estimated as FC=ΣI/(ΔS/100).

The restraint load calculation unit 554 estimates the full charge capacity FC for each cell 81, and determines the restraint load Ls using the minimum value FCmin of the estimated full charge capacity FC. For example, the relationship between the full charge capacity FC and the restraint load Ls is determined in advance through experiments or the like, and this relationship is made into a map and stored in the storage section of the control device 55. Then, the restraint load Ls is determined by searching the map using the minimum value FCmin.

The control device 55 may predict breakage of the restraint band 84 using the restraint load Ls calculated by the restraint load calculation unit 554. For example, when the restraint load Ls exceeds a preset allowable value, it may be determined that there is a possibility of the restraint band 84 breaking, and an MIL (Malfunction Indication Lamp) (not shown) may be turned on.

FIG. 4 is a flowchart showing an example of processing executed by the control device 55 in this embodiment. This flowchart is repeatedly processed every predetermined period. In step (hereinafter, step is abbreviated as "S") 10, an estimated restraint load Le is calculated. The estimated restraint load Le is calculated by the restraint load estimation unit 55b so that the restraint load increases as the usage period of the assembled battery 510 passes. In subsequent S11, it is determined whether the estimated restraint load Le is greater than or equal to a predetermined value X. If the estimated restraint load Le is less than the predetermined value X, a negative determination is made and the current routine ends. If the estimated restraint load Le is equal to or greater than the predetermined value X, an affirmative determination is made and the process proceeds to S12.

In S12, the assembled battery 510 is discharged, and the process proceeds to S13. In S13, it is determined whether the SOC of the assembled battery 510 is less than or equal to a predetermined value α. If the SOC is greater than the predetermined value α, a negative determination is made and the process returns to S12 to continue discharging the assembled battery 510. When the SOC decreases to the predetermined value α due to the discharge of the assembled battery 510, the SOC becomes equal to or less than the predetermined value α, and an affirmative determination is made in S13, and the process proceeds to S14.

In S14, discharging of the assembled battery 510 is stopped and charging/discharging is put into a suspended state, and then the process proceeds to S15. In S15, it is determined whether or not the first predetermined time T1 has elapsed since the discharging of the assembled battery 510 has stopped (charging and discharging have stopped). When the state in which charging and discharging of the assembled battery 510 is suspended has elapsed for a first predetermined time T1, an affirmative determination is made in S15 and the process proceeds to S16.

In S16, the voltage Vb is acquired as the first battery voltage V1, and the process proceeds to S17. In S17, the assembled battery 510 is charged and the charging current integrated value ΣI is calculated by integrating the current Ib.

In subsequent S18, it is determined whether the SOC of the assembled battery 510 is equal to or greater than a predetermined β. If the SOC is less than the predetermined value β, a negative determination is made and the process returns to S17 to continue charging the assembled battery 510 and continue calculating the charging current integrated value ΣI. When the SOC increases to the predetermined value β by charging the assembled battery 510, the SOC becomes equal to or higher than the predetermined value β, and an affirmative determination is made in S18, and the process proceeds to S19.

In S19, charging of the assembled battery 510 is stopped and charging/discharging is put into a suspended state, and then the process proceeds to S20. In S20, it is determined whether or not the second predetermined time T2 has elapsed since charging of the assembled battery 510 has stopped (charging and discharging have stopped). When the state in which charging and discharging of the assembled battery 510 is suspended has elapsed for a second predetermined time T2, an affirmative determination is made in S20 and the process proceeds to S21.

In S21, the voltage Vb is acquired as the second battery voltage V2, and the process proceeds to S22. In S22, as explained above, the full charge capacity FC of each cell 81 is estimated using the charging current integrated value ΣI, the first battery voltage V1, and the second battery voltage V2.

In the following S23, a map search is performed using the minimum value FCmin of the full charge capacity FC of each cell 81, and after calculating the restraint load Ls, the current routine is ended.

According to the present embodiment, when the estimated restraining load Le estimated by the restraining load estimating section 55b is equal to or greater than the predetermined value X, the diagnostic mode processing section 55c executes the diagnosis of the assembled battery. Therefore, the diagnosis of the assembled battery 510 is executed when the restraining load of the restraining band 84 is large and there is a high possibility that various malfunctions of the assembled battery 510 will occur. Labor saving is achieved.

According to the present embodiment, the diagnostic mode processing unit 55c uses the first voltage acquisition unit 551, the charging current integration unit 552, and the second voltage acquisition unit 553 to calculate the restraint load Ls. Performs charging/discharging control. Then, the restraining load Ls is calculated from the charging current integrated value ΣI, the first battery voltage, V1, and the second battery voltage V2 during the charging/discharging control for the diagnostic mode. Further, the first battery voltage V1 is the voltage when charging and discharging of the assembled battery 510 is stopped for a first predetermined time T1, and the second battery voltage V2 is the voltage when charging and discharging of the assembled battery 510 is stopped for a second predetermined time T2. This is the voltage when polarization is eliminated. Therefore, the restraining load Ls can be calculated with high accuracy. Further, when the estimated restraint load Le estimated by the restraint load estimating unit 55b exceeds a predetermined value performs charging/discharging control for the diagnostic mode and calculates the restraint load Ls, so it is possible to avoid wasting power and time.

In the embodiment described above, the restraining load estimating unit 55b estimates the estimated restraining load Le based on the usage period of the assembled battery 510. However, the estimated restraint load Le may be calculated in the restraint load estimating section 55b using the method described in Patent Document 1 mentioned above. For example, the capacity maintenance rate of the assembled battery 510 is determined by dividing the current integrated value between two appropriate points when the assembled battery 510 is being charged and discharged as usual by the SOC difference between the two points. Then, the degree of deterioration of the battery pack 510 may be determined from the capacity maintenance rate, and the estimated restraint load Le may be calculated from this degree of deterioration, the SOC, and the temperature Tb of the battery pack 510. Furthermore, the restraining load estimating section 55b may calculate the estimated restraining load Le using an output signal (output voltage) of a strain gauge provided in the assembled battery 510.

(Embodiment 2)
In the second embodiment, the diagnostic mode processing unit 55c of the control device 55 diagnoses a micro short circuit in the assembled battery 510. The configurations of the battery system and power system in Embodiment 2 are the same as those in Embodiment 1, so the parts that are different from Embodiment 1 will be described below.

FIG. 5 is a diagram illustrating functional blocks configured in the control device in the second embodiment. The control device 55 of the second embodiment includes a restraint load estimating section 55b and a diagnostic mode processing section 55c. The restraint load estimating section 55b is the same as in the first embodiment.

The diagnosis mode processing unit 55c of the second embodiment executes a diagnosis of a micro short circuit in the assembled battery 510 when the estimated restraint load Le becomes equal to or greater than a predetermined value Y. The diagnostic mode processing section 55c includes a threshold setting section 561, a cell voltage acquisition section 562, a voltage difference calculation section 563, and a micro short circuit detection section 564.

The threshold value setting unit 561 sets the threshold value S using the estimated restraint load Le estimated by the restraint load estimation unit 55b. The threshold value S is set to a smaller value as the estimated restraint load Le becomes larger.

The cell voltage acquisition unit 562 acquires the voltage (cell voltage) of each cell 81 using the voltage Vb output from the monitoring unit 52. The cell voltage acquisition unit 562 acquires the voltage of each cell 81, for example, from the voltage Vb when the assembled battery 510 is being charged.

The voltage difference calculation unit 563 calculates a voltage difference ΔVb that is the difference between the maximum value and the minimum value of the voltage of each cell 81 acquired by the cell voltage acquisition unit 562.

The micro short circuit detection unit 564 detects a micro short circuit in the assembled battery 510 (cell 81) by comparing the voltage difference ΔVb and the threshold value S. When the voltage difference ΔVb is greater than or equal to the threshold value S (ΔVb≧S), the micro short circuit detection unit 564 determines that a micro short circuit has occurred, and detects the micro short circuit. The micro short circuit may be a micro short circuit between the terminals of the cell 81 (inside the circuit of the assembled battery 510) or a micro short circuit inside the cell 81. The diagnostic mode processing unit 55c turns on the MIL 57 when the minute short circuit detection unit 564 detects a minute short circuit in the assembled battery 510.

FIG. 6 is a flowchart showing an example of processing executed by the control device 55 in the second embodiment. This flowchart is repeatedly processed every predetermined period. In S40, an estimated restraint load Le is calculated. The estimated restraint load Le is calculated by the restraint load estimation unit 55b so that the restraint load increases as the usage period of the assembled battery 510 passes. In subsequent S41, it is determined whether the estimated restraint load Le is greater than or equal to a predetermined value Y. If the estimated restraint load Le is less than the predetermined value Y, a negative determination is made and the current routine ends. If the estimated restraint load Le is greater than or equal to the predetermined value Y, an affirmative determination is made and the process proceeds to S42.

In S42, a threshold value S is set. The threshold value S is set to a smaller value as the estimated restraint load Le becomes larger. Once the threshold value S is set, the process advances to S43, and it is determined whether the assembled battery 510 is being charged. When the assembled battery 510 is not being charged, the process waits until the assembled battery 510 is being charged, and when the assembled battery 510 is being charged, an affirmative determination is made in S43 and the process proceeds to S44.

In S44, the voltage of each cell 81 (cell voltage) is acquired using the voltage Vb output from the monitoring unit 52. Note that the voltage of the cell 81 is acquired during charging of the assembled battery 510 because CC (Constant Current) charging or CCCV (Constant Current, Constant Voltage) charging is performed when charging the assembled battery 510. This is because the voltage does not change suddenly.

In the following S45, the voltage difference ΔVb, which is the difference between the maximum value and the minimum value of the voltage of each cell 81 obtained in S44, is calculated, and then the process proceeds to S46. In S46, it is determined whether the voltage difference ΔVb is greater than or equal to the threshold value S. When the voltage difference ΔVb is smaller than the threshold value S (ΔVb<S), a negative determination is made in S46 and the current routine ends. If the voltage difference ΔVb is greater than or equal to the threshold value S (ΔVb≧S), it is determined that a minute short circuit has occurred in the assembled battery 510, the process proceeds to S47, the MIL is turned on, and the current routine is ended.

According to the second embodiment, when the estimated restraint load Le estimated by the restraint load estimator 55b is equal to or greater than the predetermined value Y, the diagnostic mode processing unit 55c executes the diagnosis of the assembled battery. Therefore, the diagnosis of the assembled battery 510 is executed when the restraining load of the restraining band 84 is large and there is a high possibility that various malfunctions of the assembled battery 510 will occur. Labor saving is achieved.

According to this second embodiment, the diagnostic mode processing section 55c executes a diagnosis of a minute short circuit in the assembled battery 510. The micro short circuit detection section 564 of the diagnostic mode processing section 55c determines that a micro short circuit has occurred when the parameter (voltage difference ΔVb calculated by the voltage difference calculation section 563) indicating a micro short circuit in the assembled battery 510 is equal to or higher than the threshold value S. judge. The threshold setting unit 561 sets the threshold S to a smaller value as the estimated restraint load Le becomes larger. Therefore, the threshold S becomes a smaller value when the estimated restraint load Le is large than when the estimated restraint load Le is small. Become. Therefore, when the restraining load of the restraining band 84 is large, the detection sensitivity of micro short circuits becomes high, and micro short circuits can be detected with high accuracy. In addition, in a situation where the estimated restraining load Le estimated by the restraining load estimating section 55b is equal to or higher than the predetermined value Y and a micro short circuit is likely to occur, the diagnostic mode processing section 55c diagnoses the micro short circuit, so the assembled battery 510 can be diagnosed, thereby saving labor in diagnosis.

In this second embodiment, a minute short circuit is detected using the voltage difference ΔVb. However, it may be possible to monitor the voltage drop of the cells 81 when the battery pack 510 is not charging or discharging, and if there is a cell 81 whose voltage drop is equal to or greater than a threshold value, it may be determined that a micro short circuit has occurred. Alternatively, the resistance value of each cell 81 may be determined from the current and voltage during charging and discharging of the assembled battery 510, and if there is a cell 81 with a resistance value greater than or equal to a threshold value, it may be determined that a micro short circuit has occurred. .

In the second embodiment, detection (diagnosis) of a minute short circuit in the assembled battery 510 is performed when the estimated restraining load Le is equal to or greater than a predetermined value Y. However, when the estimated restraint load Le is smaller than the predetermined value Y, a minute short circuit in the assembled battery 510 may be detected. In this case, the magnitude of the threshold value to be compared with the voltage difference ΔVb is set to a value larger by a certain amount than the maximum value of the threshold value S set by the threshold value setting unit 561, and a micro short circuit in the assembled battery 510 is detected. Thereby, the detection sensitivity of micro short circuits can be appropriately set, and erroneous detection can be suppressed.

The control device 55 may perform the restraint load diagnosis in the first embodiment and the micro short circuit diagnosis in the second embodiment. In this case, the predetermined value Y may be set larger than the predetermined value X. According to this configuration, the threshold value setting unit 561 can set the threshold value S using the restraint load Ls calculated by the restraint load calculation unit 554 (FIG. 3: Embodiment 1), and the threshold value S can be set using the restraint load with high accuracy. It becomes possible to set.

(Modified example)
In each of the above embodiments, the battery system 50 (battery assembly 510) is a stationary battery installed in the house 10. However, the battery system (battery assembly) may be mounted on a vehicle.

FIG. 7 is a diagram showing a schematic configuration of an electric vehicle equipped with a battery system according to a modified example. In this modification, an example will be described in which the electric vehicle 100 is an electric vehicle (BEV: Battery Electric Vehicle), but the electric vehicle 100 is not limited to being a BEV. For example, the electric vehicle 100 is not limited to a BEV. Plug-in Hybrid Electric Vehicle), externally chargeable fuel cell electric vehicle (FCEV), etc. may be used.

Electric vehicle 100 includes a battery pack 101 , a boost converter 102 , an inverter 103 , a motor generator 104 , a transmission gear 105 , drive wheels 106 , and a control device 200 .

Battery pack 101 is mounted on electric vehicle 100 as a driving power source (that is, a power source) for electric vehicle 100 . The battery pack 101 is a battery pack in which assembled batteries similar to the assembled battery 510 in the above embodiment are connected in series or in parallel. A monitoring unit 107 is arranged in the battery pack 101, and detects the voltage Vb of the assembled battery (the voltage of each cell), the current Ib input/output to the assembled battery, and the temperature Tb.

Battery pack 101 is connected to boost converter 102 via system main relays 108a and 108b. Boost converter 102 is connected to inverter 103, and inverter 103 converts DC power from boost converter 102 into AC power.

Motor generator (three-phase AC motor) 104 generates kinetic energy for driving electric vehicle 100 by receiving AC power from inverter 103 . Kinetic energy generated by motor generator 104 is transmitted to drive wheels 106. On the other hand, when decelerating electric vehicle 100 or stopping electric vehicle 100, motor generator 104 converts the kinetic energy of electric vehicle 100 into electrical energy. AC power generated by motor generator 104 is converted to DC power by inverter 103 and supplied to battery pack 101 through boost converter 102 . Thereby, regenerated power can be stored in the battery pack 101.

Electric vehicle 100 is configured to include an external charging function for charging battery pack 101 with external power source 90 . Electric vehicle 100 includes a charger 109 and charging relays 110a and 110b. The external power source 90 is a power source provided outside the vehicle, and is, for example, a commercial power source. Charger 109 converts power from external power supply 90 into power for charging battery pack 101 . Charger 109 is connected to battery pack 101 via charging relays 110a and 110b. When charging relays 110a and 110b are on, battery pack 101 can be charged with power from external power source 90.

Battery pack 101 is connected to auxiliary battery 112 and auxiliary load 113 via DC/DC converter 111 . The electric power stored in battery pack 101 is stepped down by DC/DC converter 111 to charge auxiliary battery 112 and drive auxiliary load 113 .

The control device 200 includes a battery ECU 201 and a vehicle ECU 202. Functional blocks similar to the functional blocks configured in the control device 55 of the above embodiment are configured in either the battery ECU 201 or the vehicle ECU 202. For example, the SOC calculation unit 55a and the restraint load estimation unit 55b may be configured in the battery ECU 201, and the diagnostic mode processing unit 55c may be configured in the vehicle ECU 202.

In the modified example, when the estimated restraint load Le estimated by the restraint load estimation unit 55b configured in the control device 200 is equal to or greater than the predetermined value ) is diagnosed for the restraint load Ls. In this case, the processes after S12 (FIG. 4) are preferably executed when electric vehicle 100 is stopped (parked). For example, when the electric vehicle 100 is stopped (parked) and the external power source 90 is connected, the auxiliary battery 112 is charged and the auxiliary load 113 is driven to discharge the battery, and the processes from S12 to S16 are executed. do. Thereafter, charging is performed using the external power source 90, and the processes of S17 to S23 are performed. Note that a charger/discharger may be provided in place of the charger 109 to enable power supply (discharge) to the outside of the electric vehicle 100, thereby performing discharge by external power supply, and executing the processes of S12 to S16.

In the modified example, when the estimated restraint load Le estimated by the restraint load estimation unit 55b configured in the control device 200 is equal to or greater than a predetermined value Y, the diagnostic mode processing unit 55c configured in the control device 200 detects a micro short circuit of the assembled battery. Diagnose. In this case, it is preferable that the processes after S42 (FIG. 6) are executed while external charging is being performed by the external power source 90. When charging while the electric vehicle 100 is running (for example, when charging with regenerated power), there is a possibility that the voltage fluctuation of the battery pack 101 (assembled battery) becomes large. Or, this is because CCCV charging is performed and the voltage of the assembled battery does not change suddenly.

As described above, the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present disclosure is indicated by the claims, and includes all changes within the meaning and range equivalent to the claims.

1 Power system, 4 In-home power line, 10 House, 11 Distribution board, 12 Power conditioner, 13 Solar power generation device, 14 Heat pump water heater, 15 Refrigerator, 16 Air conditioner, 20 Power grid, 30 Pole transformer, 40 smart meter, 50 battery system, 51 battery, 52 monitoring unit, 53 charger/discharger, 55 control device, 55a SOC calculation unit, 55b restraint load estimation unit, 55c diagnostic mode processing unit, 60 HEMS controller, 57 MIL, 81 cell (cell), 82 resin frame, 83 end plate, 84 restraint band, 90 external power supply, 100 electric vehicle, 101 battery pack, 102 boost converter, 103 inverter, 104 motor generator, 105 transmission gear, 106 drive wheel, 107 monitoring unit, 108a, 108b system main relay, 109 charger, 110a, 110b charging relay, 111 DC/DC converter, 112 auxiliary battery, 113 auxiliary load, 200 control device, 201 battery ECU, 202 vehicle ECU, 510 assembled battery , 551 first voltage acquisition section, 552 charging current integration section, 553 second voltage acquisition section, 554 restraint load calculation section, 561 threshold setting section, 562 cell voltage acquisition section, 563 voltage difference calculation section, 564 minute short circuit detection section.

Claims (5)

An assembled battery in which a plurality of stacked single cells are restrained by a restraining member;
A control device that controls the assembled battery,
The control device includes:
a restraint load estimation unit that estimates a restraint load by the restraint member;
A battery system comprising: a diagnosis mode processing unit that executes diagnosis of the assembled battery when the restraint load estimated by the restraint load estimation unit is equal to or greater than a predetermined value. The diagnosis executed by the diagnosis mode processing unit is a diagnosis of the restraint load,
The diagnostic mode processing section includes:
When discharging the assembled battery so that the SOC of the assembled battery becomes equal to or less than a first predetermined value, and suspending charging and discharging of the assembled battery for a first predetermined period when the SOC is equal to or less than the first predetermined value; a first voltage acquisition unit that acquires a first battery voltage, which is a voltage;
a charging current integration unit that charges the assembled battery and integrates the charging current after acquiring the first battery voltage;
a second voltage acquisition unit that stops the charging and acquires a second battery voltage that is a voltage when charging and discharging of the assembled battery is stopped for a second predetermined time when the SOC becomes a second predetermined value or more;
2. The method according to claim 1, further comprising: a restraining load calculating section that calculates the restraining load based on the charging current integrated value calculated by the charging current integrating section, the first battery voltage, and the second battery voltage. Battery system as described. The first battery voltage and the second battery voltage are voltages of the unit cell,
The restraint load calculation unit estimates the full charge capacity of the unit cell based on the charging current integrated value, the first battery voltage, and the second battery voltage, and calculates a full charge capacity of the estimated full charge capacity. The battery system according to claim 2, wherein the restraint load is calculated using the smallest value. The diagnosis executed by the diagnosis mode processing unit is a diagnosis of a micro short circuit in the assembled battery,
The diagnostic mode processing section includes:
a threshold setting unit that sets a smaller threshold when the restraint load is large compared to when the restraint load is small;
The battery system according to claim 1, further comprising: a micro short circuit detection unit that determines that the micro short circuit has occurred when a parameter indicating the micro short circuit of the assembled battery is equal to or greater than the threshold value. The battery system according to claim 4, wherein the parameter indicating the micro short circuit of the assembled battery is a voltage difference between the single cells.

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