JP5724922B2 - Power storage system and abnormality determination method - Google Patents

Description

  The present invention relates to a power storage system and an abnormality determination method capable of detecting a resistance abnormality of an electrical component electrically connected to a power storage device.

  In a system for charging and discharging an assembled battery, various electrical components are connected to the assembled battery. In Patent Document 1, it is determined whether or not the battery is in an abnormal state by measuring the voltage value of the battery and comparing the voltage value and the threshold value.

JP 2010-117235 A

  With the technique described in Patent Document 1, it is possible to determine the abnormality of the battery, but it is not possible to determine the abnormality of the electrical component connected to the battery.

  Here, as a method for determining an abnormality of an electrical component, the voltage at both ends of the electrical component and the current value flowing through the electrical component are detected, and the resistance value calculated from the voltage value and the current value increases. By determining whether or not there is an electrical component, it is possible to determine whether or not the electrical component is abnormal. In this case, a voltage sensor for detecting the voltage value of the electrical component is required.

  A power storage system according to a first invention of the present application includes a power storage element that performs charging / discharging, a DC / DC converter that switches between energization and non-energization of a transistor and boosts an output voltage of the power storage element, and a power storage element and a DC / DC converter And an electrical component disposed in a current path between. The controller controls driving of the DC / DC converter. The controller periodically switches between energization and non-energization of the transistor to generate an AC signal, and uses the voltage fluctuation amount when the AC signal is passed through the storage element and the electrical component as an index for determining an abnormality of the electrical component.

  According to the first aspect of the present application, the amount of voltage fluctuation in the power storage element can be reduced by flowing an AC signal through the power storage element and the electrical component. Therefore, the amount of voltage fluctuation when an AC signal is passed through the storage element and the electrical component is attributed to the electrical component, and this voltage variation is used to determine whether or not the electrical component is abnormal. Can do.

  An electrical component abnormality includes poor contact of electrical components. If an abnormality occurs in the electrical component, the resistance value of the electrical component is likely to increase, and if the resistance value increases, the voltage fluctuation amount also increases. If the voltage fluctuation amount when the electrical component is normal is acquired, the voltage fluctuation amount when the AC signal is passed is compared with the voltage fluctuation amount when the electrical component is normal. It is possible to determine whether or not is abnormal.

  The resistance value when an AC signal is passed through the power storage element and the electrical component can be used as an index for determining the abnormality of the electrical component. The resistance value can be calculated from the voltage fluctuation amount described above and the current value flowing through the power storage element and the electrical component. The amount of voltage fluctuation can be acquired using a voltage sensor, and the current value can be acquired using a current sensor. The voltage sensor is used to detect a voltage of a circuit including the storage element and the electrical component, and is used for determining an abnormality of the electrical component. Therefore, it is possible to determine the abnormality of the electrical component without increasing the number of components.

  When the difference between the calculated resistance value and the resistance value serving as a circuit reference is higher than a predetermined threshold value, it can be determined that the electrical component is abnormal. The reference resistance value is a reference value for determining an abnormality of the electrical component. As this resistance value, for example, the resistance value when the storage element and the electrical component are in the initial state can be used. The initial state is a state immediately after the storage element and the electrical component are assembled.

  When the average value of the AC signal is substantially constant, it is possible to perform processing for determining an abnormality of the electrical component. Specifically, when determining an abnormality of an electrical component using a resistance value, a resistance value calculated when the average value of the AC signal is substantially constant can be used as an index for determining the abnormality. By making the average value of the AC signal substantially constant, it becomes easy to reduce the voltage fluctuation of the power storage element, and it is easy to determine the abnormality of the electrical component using the voltage fluctuation amount or the resistance value. The power storage element can be mounted on a vehicle and can output energy used for traveling of the vehicle.

  A second invention of the present application is an abnormality determination method for determining an abnormality of the power storage system described in the first invention of the present application. Specifically, an alternating current signal is generated by periodically switching between energization and non-energization of the transistor, and the amount of voltage fluctuation when the alternating current signal is passed through the storage element and the electrical component is used as an index for determining an abnormality of the electrical component. Use. Also in the second invention of the present application, the same effect as that of the first invention of the present application can be obtained.

It is a figure which shows the structure of the battery system which is Example 1. FIG. 5 is a flowchart illustrating processing for determining an abnormality of an electrical component in the first embodiment. It is a figure which shows the resistance component of an assembled battery and an electrical component when an alternating current signal is used. It is a figure which shows the resistance component of an assembled battery and an electrical component when a DC signal is used.

  Examples of the present invention will be described below.

  A battery system (power storage system) that is Embodiment 1 of the present invention will be described. FIG. 1 is a diagram illustrating a configuration of a battery system. The battery system of the present embodiment can be mounted on a vehicle. The vehicle includes a hybrid vehicle and an electric vehicle. The hybrid vehicle includes an engine or a fuel cell as a power source for running the vehicle in addition to the assembled battery described later. An electric vehicle includes only an assembled battery as a power source for running the vehicle.

  The assembled battery 10 includes a plurality of single cells (storage elements) 11 connected in series. As the cell 11, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor (capacitor) can be used instead of the secondary battery. The number of unit cells 11 constituting the assembled battery 10 can be appropriately set in consideration of the required output of the assembled battery 10 and the like. The assembled battery 10 may include a plurality of unit cells 11 connected in parallel.

  An electrical component 20 is electrically connected to the assembled battery 10. The electrical component 20 is an electrical component (excluding the unit cell 11) arranged in a current path when the assembled battery 10 is charged and discharged. In this embodiment, the current path here is a current path between the assembled battery 10 and a DC / DC converter 50 described later. Examples of the electrical component 20 include a relay, a cable, and a bus bar. In FIG. 1, these electric components 20 are collectively shown as resistors.

  By switching between ON and OFF, the relay connects the assembled battery 10 to a load (such as a DC / DC converter 50 described later) or interrupts the connection between the assembled battery 10 and the load. The relay receives a control signal from the controller 40 and switches between on and off. The cable is a wiring for connecting the positive terminal and the negative terminal of the assembled battery 10 to a load. The bus bar is used to electrically connect the plurality of unit cells 11 and is connected to the positive terminal and the negative terminal of the unit cell 11.

  The current sensor 31 detects the value of the current flowing through the assembled battery 10 and outputs the detection result to the controller 40. The voltage sensor 32 detects the voltage value of the circuit including the assembled battery 10 and the electrical component 20 and outputs the detection result to the controller 40. The controller 40 has a built-in memory 41. The memory 41 stores information for operating the controller 40 and the like. The memory 41 can also be provided outside the controller 40.

  The DC / DC converter 50 boosts the output voltage of the assembled battery 10 and outputs the boosted power to the inverter 61. Further, the DC / DC converter 50 can step down the voltage output from the inverter 61 and output it to the assembled battery 10. The DC / DC converter 50 includes a reactor 51, diodes 52 and 53, and transistors (npn transistors) 54 and 55 as switching elements. Reactor 51 has one end connected to electrical component 20 and the other end connected to the connection point of transistors 54 and 55.

  The transistors 54 and 55 are connected in series, and a control signal from the controller 40 is input to the bases of the transistors 54 and 55. Diodes 52 and 53 are connected between the collectors and emitters of the transistors 54 and 55 so that current flows from the emitter side to the collector side, respectively.

  As the transistors 54 and 55, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used. In place of the npn transistor, a power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) may be used.

  When the DC / DC converter 50 boosts the output voltage of the assembled battery 10, the controller 40 turns on the transistor 55 and turns off the transistor 54. Thereby, current flows from the assembled battery 10 to the reactor 51, and magnetic energy corresponding to the amount of current is accumulated in the reactor 51. Next, the controller 40 causes the current to flow from the reactor 51 to the inverter 61 via the diode 52 by switching the transistor 55 from on to off. Thereby, the energy accumulated in the reactor 51 is released, and the boosting operation is performed.

  On the other hand, when the DC / DC converter 50 steps down the output voltage of the inverter 61, the controller 40 turns on the transistor 54 and turns off the transistor 55. Thereby, the electric power from the inverter 61 is supplied to the assembled battery 10, and the assembled battery 10 is charged.

  The inverter 61 converts the DC power from the DC / DC converter 50 into AC power and outputs the AC power to the motor / generator 62. As the motor generator 62, a three-phase AC motor can be used. Motor generator 62 receives AC power from inverter 61 and generates kinetic energy for running the vehicle. The kinetic energy generated by the motor generator 62 is transmitted to the wheels.

  When the vehicle is decelerated or stopped, the motor generator 62 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 61 converts the AC power generated by the motor / generator 62 into DC power and outputs the DC power to the DC / DC converter 50. The DC / DC converter 50 steps down the output voltage of the inverter 61 and outputs the reduced power to the assembled battery 10. Thereby, regenerative energy can be stored in the assembled battery 10.

  Next, a process for detecting an abnormality of the electrical component 20 in the battery system of the present embodiment will be described. FIG. 2 is a flowchart showing a process for detecting an abnormality of the electrical component 20. The process shown in FIG. 2 is executed by the controller 40.

  In step S <b> 101, the controller 40 generates an AC signal by controlling the driving of the transistors 54 and 55 in the DC / DC converter 50. Specifically, the controller 40 generates an AC signal by periodically switching the transistor 54 or the transistor 55 on and off. By changing the timing when the transistors 54 and 55 are turned on and off, the frequency of the AC signal can be set. For example, the frequency can be set to 400 Hz or more.

  The AC signal can be generated using a current value when charging or discharging the assembled battery 10. When the battery pack 10 is discharged, an AC signal can be generated by switching the transistor 55 on and off. On the other hand, when the current from the inverter 61 is passed through the assembled battery 10, an alternating current signal can be generated by switching the transistor 56 on and off.

  The timing for generating the AC signal can be set as appropriate. For example, an AC signal can be generated before the vehicle travels, or an AC signal can be generated while the vehicle is traveling.

  Before the vehicle travels, for example, when the ignition switch is switched from OFF to ON, an AC signal can be generated. Information relating to turning on and off the ignition switch is input to the controller 40. The controller 40 can drive the transistors 54 and 55 based on the ignition switch ON signal to generate an AC signal. While the vehicle is traveling, an AC signal can be generated in a situation where the current value is unlikely to fluctuate. A situation in which the current value hardly fluctuates is, for example, when the ignition switch is on and the vehicle is stopped.

  In step S <b> 102, the controller 40 acquires a current value based on the output of the current sensor 31 and supplies a voltage based on the output of the voltage sensor 32 in a state where an AC signal is passed through the assembled battery 10 and the electrical component 20. Get the value. The controller 40 acquires the history of the current value and the voltage value and stores the history information in the memory 41 by flowing an AC signal to the assembled battery 10 and the electrical component 20 for a predetermined time.

  In step S <b> 103, the controller 40 uses the history information stored in the memory 41 to calculate the resistance value of the circuit including the assembled battery 10 and the electrical component 20. Specifically, the controller 40 calculates the voltage fluctuation ΔV using voltage values acquired at different timings. Then, the controller 40 calculates the resistance value of the circuit including the assembled battery 10 and the electrical component 20 by dividing the voltage fluctuation ΔV by the average current value of the AC signal. The resistance value calculated in step S103 (referred to as a calculated resistance value) includes the resistance component of the assembled battery 10 and the resistance component of the electrical component 20.

  By flowing an AC signal to the assembled battery 10, the voltage fluctuation ΔV of the assembled battery 10 can be reduced, and the resistance component of the assembled battery 10 can also be reduced. Here, the average current value of the AC signal is preferably substantially constant. When the average current value changes, a voltage fluctuation ΔV of the assembled battery 10 occurs, and the resistance component of the assembled battery 10 is likely to be included in the calculated resistance value.

  By reducing the resistance component of the assembled battery 10, as shown in FIG. 3, the ratio of the resistance component of the electrical component 20 in the calculated resistance value may be higher than the ratio of the resistance component of the assembled battery 10. it can. Thereby, it becomes easy to monitor the resistance component of the electrical component 20 using the calculated resistance value.

  Here, when a direct current is passed through the assembled battery 10 and the electrical component 20, the voltage value of the assembled battery 10 fluctuates, and the resistance component of the assembled battery 10 is likely to be included in the calculated resistance value as shown in FIG. turn into. Moreover, since the assembled battery 10 deteriorates depending on the usage state, the passage of time, and the like, the resistance component of the assembled battery 10 increases in accordance with the deterioration of the assembled battery 10. In this case, it becomes impossible to distinguish between the resistance component of the assembled battery 10 and the resistance component of the electrical component 20, and it becomes difficult to monitor the resistance component of the electrical component 20 based on the calculated resistance value.

  In step S104, the controller 40 compares the calculated resistance value with the reference resistance value, and calculates a difference ΔR between the calculated resistance value and the reference resistance value. Further, the controller 40 determines whether or not the difference ΔR is higher than the threshold value Rth.

  The reference resistance value is a resistance value that serves as a reference when determining an abnormality of the electrical component 20. As a reference resistance value setting method, for example, immediately after the battery system of this embodiment is assembled, the resistance value (initial resistance value) of a circuit including the assembled battery 10 and the electrical component 20 is measured, and this initial resistance value is determined. The reference resistance value can be used. Information relating to the reference resistance value can be stored in the memory 41.

  The threshold value Rth is an index for determining an abnormality of the electrical component 20. As a method for setting the threshold value Rth, first, a resistance value when the electrical component 20 is in an abnormal state can be measured in advance, and a difference between the resistance value in the abnormal state and the reference resistance value can be set as the threshold value Rth. When a contact failure or the like occurs in the electrical component 20 due to an external impact or the like, the resistance value of the electrical component 20 increases. Therefore, the resistance value at this time is set to a resistance value when the electrical component 20 is in an abnormal state. Can do. As the resistance value of the electrical component 20 increases, the difference ΔR becomes higher than the threshold value Rth.

  By monitoring the increase in resistance of the electrical component 20, the heat generation state of the electrical component 20 can be monitored. That is, it can be determined whether or not the heat generation of the electrical component 20 is abnormal.

  In step S104, when the difference ΔR between the calculated resistance value and the reference resistance value is higher than the threshold value Rth, the process proceeds to step S105. Otherwise, the process proceeds to step S106. In step S105, the controller 40 determines that an abnormality has occurred in the electrical component 20. In step S106, the controller 40 determines that no abnormality has occurred in the electrical component 20.

  When an abnormality occurs in the electrical component 20, the controller 40 can prevent charging and discharging of the assembled battery 10. Specifically, the controller 40 can switch the relay for connecting the assembled battery 10 and the DC / DC converter 50 from on to off, and thereby disconnect the connection between the assembled battery 10 and the DC / DC converter 50.

  On the other hand, the controller 40 can notify a user or the like of information indicating that an abnormality has occurred in the electrical component 20. As a notification method to the user, display on a display, audio output, or the like can be used.

  For example, information indicating that an abnormality has occurred in the electrical component 20 can be displayed on a display mounted on a vehicle or a display provided on a terminal owned by a user. In addition, information indicating that an abnormality has occurred in the electrical component 20 can be output as sound from a speaker mounted on the vehicle or a speaker provided in a terminal owned by the user. Information indicating that an abnormality has occurred in the electrical component 20 may be any information that allows a user or the like to recognize that an abnormality has occurred in the electrical component 20. When using the user's terminal, it is necessary to transmit information indicating that an abnormality has occurred in the electrical component 20 from the vehicle to the terminal via wireless or wired communication.

  According to the present embodiment, the abnormality of the electrical component 20 can be determined only by using the current sensor 31 and the voltage sensor 32 for detecting the current value and the voltage value of the circuit including the assembled battery 10 and the electrical component 20. it can. In other words, the abnormality of the electrical component 20 can be determined without increasing the number of components.

  The electrical component 20 may include a plurality of electrical components. If an abnormality occurs in any of the electrical components, the calculated resistance value tends to be higher than the reference resistance value. The difference ΔR in resistance value tends to be higher than the threshold value Rth. Therefore, when the electrical component 20 includes a plurality of electrical components, it can be determined that an abnormality has occurred in any of the electrical components.

  In this embodiment, whether or not the electrical component 20 is abnormal is determined based on the resistance value of the circuit including the assembled battery 10 and the electrical component 20, but the present invention is not limited to this. The voltage value of the circuit including the assembled battery 10 and the electrical component 20 can be detected, and it can be determined whether or not the electrical component 20 is abnormal based on the fluctuation amount of the voltage value.

  Specifically, in the process of step S103, the fluctuation amount of the voltage value is acquired, and the difference is calculated by comparing the acquired fluctuation amount with the reference fluctuation amount. The voltage fluctuation amount difference corresponds to the difference ΔR calculated in step S103. Next, in step S104, it is determined whether or not the difference in voltage fluctuation amount is larger than a threshold value. When the voltage fluctuation amount difference is larger than the threshold value, it can be determined that an abnormality has occurred in the electrical component 20. When the difference in voltage fluctuation amount is smaller than the threshold value, it can be determined that no abnormality has occurred in the electrical component 20. The threshold value used here corresponds to the threshold value Rth, but becomes a different value depending on the current value.

  In the present embodiment, the AC signal is generated using the DC / DC converter 50, but the present invention is not limited to this. For example, in the configuration shown in FIG. 1, when a charger is connected to the positive terminal and the negative terminal of the assembled battery 10, an AC signal can be generated in the charger. The charger is used to supply power from an external power source to the assembled battery 10. The external power source is a power source provided outside the vehicle. As the external power source, for example, a commercial power source can be used.

  When charging the assembled battery 10 using the charger, the assembled battery 10 is charged with a constant current. For this reason, if an alternating current signal is included in the charging current, the abnormality determination of the electrical component 20 can be performed as in the present embodiment.

10: assembled battery 11: single battery 20: electrical component 31: current sensor 32: voltage sensor 40: controller 41: memory 50: DC / DC converter 51: reactor 52, 53: diode 54, 55: transistor 61: inverter 62: Motor generator

Claims (11)

A power storage element for charging and discharging; and
A DC / DC converter that switches between energization and de-energization of the transistor to boost the output voltage of the power storage element;
An electrical component disposed in a current path between the storage element and the DC / DC converter;
A controller for controlling the driving of the DC / DC converter,
The controller periodically switches between energization and non-energization of the transistor to generate an AC signal, and the voltage fluctuation amount when the AC signal is passed through the power storage element and the electrical component is determined as an abnormality of the electrical component. A power storage system characterized by being used as an index for determination. A voltage sensor for detecting a voltage value of a circuit including the storage element and the electrical component;
A current sensor for detecting a current value flowing through the circuit,
The controller calculates a resistance value from the voltage fluctuation amount acquired using the voltage sensor and a current value acquired using the current sensor, and uses the calculated resistance value as the index. The power storage system according to claim 1.   The controller determines that the electrical component is abnormal when a difference between the calculated resistance value and a resistance value serving as a reference of the circuit is higher than a predetermined threshold value. 2. The electricity storage system according to 2.   The power storage system according to any one of claims 1 to 3, wherein the controller performs a process of determining an abnormality of the electrical component when an average value of the AC signal is substantially constant.   The power storage system according to claim 2 or 3, wherein the controller uses the resistance value calculated when the average value of the AC signal is substantially constant as the index.   The power storage system according to any one of claims 1 to 5, wherein the power storage element outputs energy used for running the vehicle. An abnormality determination method for determining an abnormality of a power storage system,
The power storage system includes:
A power storage element for charging and discharging; and
A DC / DC converter that switches between energization and de-energization of the transistor to boost the output voltage of the power storage element;
An electrical component disposed in a current path between the power storage element and the DC / DC converter,
An alternating current signal is generated by periodically switching energization and non-energization of the transistor, and the amount of voltage fluctuation when the alternating current signal is passed through the storage element and the electrical component is used as an index for determining an abnormality of the electrical component. An abnormality determination method characterized by being used. Detecting a voltage value of a circuit including the storage element and the electrical component;
Detecting the current value flowing through the circuit,
The abnormality determination method according to claim 7, wherein a resistance value is calculated from the detected fluctuation amount of the voltage value and the detected current value, and the calculated resistance value is used as the index.   9. The electrical component is determined to be abnormal when a difference between the calculated resistance value and a resistance value serving as a reference of the circuit is higher than a predetermined threshold value. Abnormality judgment method.   The abnormality determination method according to any one of claims 7 to 9, wherein when the average value of the AC signal is substantially constant, a process for determining an abnormality of the electrical component is performed. The abnormality determination method according to claim 8 or 9, wherein the resistance value calculated when an average value of the AC signal is substantially constant is used as the index.

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