Power supply system, anomaly detection method for current sensor, anomaly detection program, and recording medium

Abstract

A power storage module supplies a current to a load. A current sensor is connected in series to the power storage module and measures a current flowing in the power storage module. A control unit: changes the state of a discharge switch included in a discharge circuit connected in parallel to the load; acquires a plurality of current measurement values from the current sensor; and executes anomaly determination for the current sensor on the basis of the plurality of acquired measurement values.

Description

Power supply system, current sensor abnormality detection method, abnormality detection program, and recording medium

[0001] The present disclosure relates to a power supply system equipped with a current sensor, a current sensor abnormality detection method, an abnormality detection program, and a recording medium.

[0002] In power supply systems using lithium-ion batteries, etc., high reliability is required for sensors that measure the battery's voltage, current, and temperature to ensure battery safety. In particular, in automotive systems, it is essential to verify the integrity of each sensor from the perspective of functional safety. Various methods for verifying the integrity of current sensors have been proposed (see, for example, Patent Documents 1 to 5).

[0003] JP 2013-542418 A JP 2004-006131 A JP 2010-57342 A JP 2009-118673 A JP 2020-99112 A

[0004] Conventional methods for checking the soundness of current sensors include using duplicated current sensors and measuring the precharge current at multiple points during startup. The former method is costly, while the latter method is prone to erroneous judgments if noise occurs during sampling, since the number of samples that can be measured during the precharge time during startup is limited.

[0005] The present disclosure has been made in view of these circumstances, and its purpose is to provide a technology for checking the soundness of a current sensor mounted on a power supply system at low cost and with high accuracy.

[0006] In order to solve the above problems, a power supply system according to one aspect of the present disclosure includes a storage module for supplying current to a load, a current sensor connected in series to the storage module and measuring the value of the current flowing through the storage module, and a control unit that acquires the current measurement value from the current sensor, wherein the control unit changes the state of a discharge switch included in a discharge circuit connected in parallel to the load to acquire multiple current measurement values ​​from the current sensor, and performs an abnormality determination for the current sensor based on the multiple acquired measurement values.

[0007] Any combination of the above components, and conversion of the expression of the present disclosure into an apparatus, system, method, computer program, recording medium, etc., are also valid aspects of the present disclosure.

[0008] According to the present disclosure, the soundness of a current sensor mounted on a power supply system can be confirmed at low cost and with high accuracy.

[0009] FIG. 1 is a diagram showing an example of the configuration of a power supply system mounted on an electric vehicle according to an embodiment; FIG. 2 is a diagram showing an example of the configuration of a power supply system mounted on an electric vehicle according to a comparative example; FIG. 3 is a diagram showing an example of transitions of pre-charge current and capacitor voltage at the start of an electric vehicle; FIG. 4 is a flowchart showing the flow of a method for detecting an abnormality in a current sensor according to a first embodiment; FIG. 5 is a flowchart showing the flow of a method for detecting an abnormality in a current sensor according to a second embodiment; and FIG. 6 is a flowchart showing the flow of a method for detecting an abnormality in a current sensor according to a third embodiment.

[0010] FIG. 1 is a diagram showing an example of the configuration of a power supply system 1 mounted on an electric vehicle according to an embodiment. In this embodiment, the electric vehicle is assumed to be a pure EV that does not have an internal combustion engine. The electric vehicle includes a motor 3, an inverter 2, a power supply system 1, and a control unit 20. If the electric vehicle is a hybrid vehicle, these components represent the components of the electric system. The power supply system 1 includes a battery module 11, a battery management device 12, and a fan 13.

[0011] Generally, a three-phase AC motor is used as the motor 3 for driving an electric vehicle. During power running, the inverter 2 converts DC power supplied from the battery module 11 into AC power and supplies it to the motor 3. The motor 3 rotates in accordance with the AC power supplied from the inverter 2. During regeneration, the rotational energy generated by deceleration is converted into AC power and supplied to the inverter 2. The inverter 2 converts AC power supplied from the motor 3 into DC power and supplies it to the battery module 11.

[0012] A large-capacity capacitor C1 is connected in parallel to the inverter 2. The capacitor C1 smoothes the voltage of the power line connecting the inverter 2 and the battery module 11. Main relays RY1 and RY2 are connected to the power line to connect / disconnect the battery pack 10 and the load in the electric vehicle. The main relays RY1 and RY2 are also called contactor relays. A series circuit of a pre-charge resistor Rp and a pre-charge relay RYp (hereinafter referred to as a pre-charge circuit) is connected in parallel to the main relay RY1. The pre-charge circuit is mainly used to prevent inrush current at startup.

[0013] A series circuit (hereinafter referred to as a discharge circuit) consisting of a discharge resistor Rd and a discharge switch Sd is connected in parallel to the inverter 2 and the capacitor C1. When the discharge switch Sd is controlled to be in an on state, the charge accumulated in the capacitor C1 can be discharged. A relay or a semiconductor switch can be used as the discharge switch Sd.

[0014] In the case of pure EVs, the power lines are often designed for 400 V or more, and a large-capacity electrolytic capacitor is often used for capacitor C1. In this case, even after the main relays RY1 and RY2 are controlled to the off state, the charge accumulated in capacitor C1 keeps the voltage of the power lines high. If a user or maintenance person accidentally touches the high-voltage power line, there is a risk of electric shock.

[0015] The control unit 20 is a vehicle ECU (Electronic Control Unit) that controls the entire electric vehicle, and may be configured as, for example, an integrated VCM (Vehicle Control Module). The main relays RY1 and RY2 and the precharge relay RYp may be controlled by the vehicle ECU or by a control unit 122 in the battery pack 10.

[0016] The battery module 11 includes multiple cells E1-En connected in series. The number of cells connected in series is determined by the specifications of the motor 3. The cells may be lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, or the like. In the following description, we will assume an example in which lithium-ion battery cells (nominal voltage: 3.6-3.7V) are used. Note that in each series stage of cells, multiple cells may be connected in parallel to increase capacity.

[0017] The battery management device 12 includes a measurement unit 121 and a control unit 122. The measurement unit 121 is composed of an AFE (Analog Front End) IC or ASIC (Application Specific Integrated Circuit) and memory. In other words, the control unit 122 is realized by a computer having a CPU and memory, and the computer functions as the control unit 122 when the CPU executes a program stored in the memory. Here, the program is pre-recorded in the memory of the control unit 122, but it may also be provided via a telecommunications line such as the Internet or recorded on a (non-transitory) recording medium such as a memory card. The control unit 122 is composed of a microcontroller and controls the entire battery pack 10 by executing a predetermined program.

[0018] The measurement unit 121 is connected to each node of the multiple cells E1-En connected in series by multiple voltage measurement lines, and measures the voltage of each cell E1-En by measuring the voltage between each two adjacent voltage measurement lines.

[0019] The measurement unit 121 includes a multiplexer and an A / D converter. The multiplexer outputs the voltages of the multiple cells E1-En to the A / D converter in a predetermined order. The A / D converter converts the analog voltages input from the multiplexer into digital values. The measurement unit 121 transmits the voltage values ​​of the cells E1-En, converted into digital values, to the control unit 122 via a serial communication interface.

[0020] The current sensor I1 is connected in series to the battery module 11 and measures the current flowing through the battery module 11. The current sensor I1 can be configured, for example, with a shunt resistor connected to the power line and a differential amplifier. The differential amplifier amplifies the voltage across the shunt resistor and outputs it to an A / D converter in the measurement unit 121. Note that a Hall element may be used instead of the shunt resistor. The A / D converter in the measurement unit 121 converts the analog voltage indicating the current flowing through the battery module 11, which is input from the differential amplifier, into a digital value. The measurement unit 121 transmits the converted current value to the control unit 122 via a serial communication interface. The measurement may be performed by the control unit 122.

[0021] A temperature sensor T1 is installed on the surface of the battery module 11. The temperature sensor T1 can be configured, for example, with a thermistor and a voltage dividing resistor. The divided voltage of the thermistor and the voltage dividing resistor is input to the measurement unit 121. An A / D converter in the measurement unit 121 converts the input analog voltage indicating the temperature into a digital value. The measurement unit 121 transmits the converted digital temperature value to the control unit 122 via a serial communication interface.

[0022] The control unit 122 manages the states of the cells E1 to En based on the voltage values ​​of the cells E1 to En, the current values ​​flowing through the battery module 11, and the temperature values ​​of the battery module 11 received from the measurement unit 121.

[0023] The control unit 122 estimates the SOC (State Of Charge) by combining the OCV (Open Circuit Voltage) method and the current integration method. The OCV method estimates the SOC based on the measured cell OCV and the cell's SOC-OCV curve. The cell's SOC-OCV curve is created in advance by the battery manufacturer based on characteristic tests and is registered in the control unit 122 at the time of shipment.

[0024] The current integration method is a method for estimating the SOC based on the OCV at the start of cell charging and discharging and the integrated value of the measured current. With the current integration method, current measurement errors accumulate as the charging and discharging time increases. Therefore, it is preferable to use a weighted average of the SOC estimated by the current integration method and the SOC estimated by the OCV method.

[0025] The control unit 122 controls the fan 13 for cooling the battery module 11 based on the temperature value of the battery module 11 received from the measurement unit 121. The fan 13 is a load connected to both ends of the battery module 11 and operates by receiving a current supply from the battery module 11. The control unit 122 can control the rotation speed of the fan 13, and increases the rotation speed as the temperature value of the battery module 11 increases from a reference temperature value.

[0026] The control unit 122 of the battery pack 10 and the control unit 20 of the electric vehicle are connected via an in-vehicle network. The in-vehicle network may be, for example, a Controller Area Network (CAN) or a Local Interconnect Network (LIN). The control unit 122 can transmit the voltage, current, temperature, SOC, and various control signals of the battery module 11 to the control unit 20 via the in-vehicle network.

[0027] When the control unit 122 of the battery pack 10 detects any of overcharging, over-discharging, overcurrent, and abnormal temperature, it sends a cutoff signal to the control unit 20 on the electric vehicle side to turn off the main relays RY1 and RY2. Note that if the control unit 122 of the battery pack 10 is designed to directly control the on / off of the main relays RY1 and RY2, the control unit 122 of the battery pack 10 will directly turn off the main relays RY1 and RY2 when it detects any of the above abnormalities in the battery module 11.

[0028] A method for checking the soundness of the current sensor I1 will now be considered.

[0029] FIG. 2 is a diagram showing a comparative example of the configuration of a power supply system 1 mounted on an electric vehicle. In this comparative example, two current sensors I1 and I2 are installed on the power line for redundancy. The control unit 122 compares the measured values ​​of the first current sensor I1 and the second current sensor I2, and if the difference between the two is greater than a predetermined value, determines that an abnormality has occurred in one of the current sensors. In this case, the control unit 122 turns off the main relays RY1 and RY2 and sends a current sensor abnormality detection signal to the control unit 20. Alternatively, if the system is used in a manner where a sudden system shutdown would pose a danger to the user, the control unit 20 is notified to limit battery output. This method is highly robust but expensive.

[0030] In some electric vehicles, an auxiliary battery (usually a 12V lead battery) is connected to the power line via a DC / DC converter (not shown). In this case, the measurement value of current sensor I1 is compared with the measurement value of a current sensor (not shown) in the DC / DC converter to determine whether an abnormality has occurred in either current sensor. However, this method can only be used in electric vehicles in which the power line and auxiliary battery are connected via a DC / DC converter.

[0031] Returning to the configuration of FIG. 1 , a comparative example of a method for checking the integrity of the current sensor I1 when only one current sensor I1 is installed will now be described. When the driver turns on the power to the electric vehicle (equivalent to turning on the ignition of an internal combustion engine vehicle), the control unit 20 first controls the pre-charge relay RYp to the on state. In this state, the capacitor C1 is charged while the current from the battery module 11 is limited via the pre-charge resistor Rp. After a predetermined time has elapsed since turning on the pre-charge relay RYp, the control unit 20 turns off the pre-charge relay RYp and turns on the main relays RY1 and RY2 (soft start).

[0032] The precharge period for charging the capacitor C1 through the precharge resistor Rp is generally set to within several hundred ms in consideration of usability, and the sampling period of the current sensor I1 is generally set to several tens of ms to 100 ms.

[0033] 3 is a diagram showing an example of transitions in pre-charge current and capacitor voltage during start-up of an electric vehicle. When the driver turns on the power supply to the electric vehicle and the pre-charge relay RYp is turned on by the control unit 20, a pre-charge current begins to flow to the capacitor C1, and the pre-charge current decreases over time, causing the voltage of the capacitor C1 to rise. In the example shown in FIG. 3, charging of the capacitor C1 is completed approximately 200 ms after start-up.

[0034] The control unit 122 compares the current characteristics of the pre-charge period measured in advance with the measured value of the current measured by the current sensor I1 during the pre-charge period, and when the difference between the expected value obtained from the current characteristics and the measured value deviates by more than a predetermined value, it determines that an abnormality has occurred in the current sensor I.

[0035] As described above, if a measurement unit 121 with a sampling period of 100 ms is used, it is only possible to acquire current values ​​at one or two points during the precharge period. If large noise enters the power line at the time of acquisition, it becomes impossible to accurately determine the health of the current sensor I1. The influence of noise may result in the current sensor I1, which is actually functioning normally, being erroneously determined to be abnormal. On the other hand, if the sampling period is increased only during the precharge period, a larger number of samples can be obtained, but this may complicate control.

[0036] 4 is a flowchart showing the flow of a method for detecting an abnormality in the current sensor I1 according to the first embodiment. When the driver turns off the power to the electric vehicle (corresponding to turning off the ignition of an internal combustion engine vehicle) (Y in S10), the control unit 20 stops the operation of the inverter 2. This stops the operation of the motor 3, which is the main load to which the battery module 11 supplies current. All other loads connected to the battery module 11 are also stopped.

[0037] The control unit 122 rotates the fan 13 at a rotation speed N (S11). An initial value of the rotation speed N is set in advance. For example, it may be set to 1000 rpm. The control unit 122 acquires a measured current value from the current sensor I1 (S12). The control unit 122 calculates the difference between an expected current value at the rotation speed N of the fan 13 and the measured value measured by the current sensor I1 (S13).

[0038] The estimated value of the current at the rotation speed N of the fan 13 is derived in advance by experiment or simulation and is registered in advance in the control unit 122. Note that the estimated value of the current at the rotation speed N of the fan 13 may be a value corrected based on the measured value of the voltage of the battery module 11 and the measured value of the temperature sensor T1. In this case, the voltage correction coefficient and the temperature correction coefficient are also derived in advance by experiment or simulation and are registered in advance in the control unit 122.

[0039] The control unit 122 increments the parameter i (S14). The initial value of the parameter i is set to 1. The control unit 122 determines whether the parameter i has exceeded a first set value (S15). The first set value is set to a value according to the number of samplings of the current value at each rotation speed N of the fan 13. For example, the first set value may be set to 3 to 5.

[0040] If the parameter i is equal to or less than the first set value (N in S15), the process proceeds to step S12, and the processes of steps S12 to S14 are repeated. If the parameter i exceeds the first set value (Y in S15), the control unit 122 adds an increase value α to the rotation speed N of the fan 13 (S16). Because the change in the rotation speed N of the fan 13 is implemented to change the load conditions, the increase value α needs to be set to a value that significantly changes the current consumption of the fan 13. For example, it may be set to 1000 rpm.

[0041] The control unit 122 determines whether the rotation speed N has exceeded a second set value (S17). The second set value is set to a value corresponding to the number of settings for the load condition. For example, it may be set to 5000 rpm. If the rotation speed N is equal to or less than the second set value (N in S17), the process proceeds to step S11, and the processes of steps S11 to S16 are repeated. If the rotation speed N has exceeded the second set value (Y in S17), the control unit 122 calculates the average value of the differences of each sample (S18). When calculating the average value of the differences of each sample, the control unit 122 preferably normalizes each difference so that the rotation speed N is under the same condition. Note that instead of calculating the average value of multiple differences, the control unit 122 may calculate the median of multiple differences.

[0042] The control unit 122 compares the average value of the differences with a threshold value (S19). The threshold value is set to the allowable error between the estimated value and the measured value of the current sensor I1. If the average value of the differences exceeds the threshold value (Y in S19), the control unit 122 determines that the current sensor I1 is abnormal (S110).

[0043] 5 is a flowchart showing the flow of a method for detecting an abnormality in the current sensor I1 according to Example 2. When the driver turns off the power to the electric vehicle (Y in S20), the control unit 20 stops all loads connected to the battery module 11, including the inverter 2. The control unit 20 turns on the discharge switch Sd (S20a) and waits until the voltage of the power line drops to 0V.

[0044] The control unit 122 controls both the main relays RY1, RY2 and the pre-charge relay RYp to the OFF state (S21). The control unit 122 acquires a measured current value from the current sensor I1 (S22). The control unit 122 calculates the difference between the estimated current value (0 A) when both the main relays RY1, RY2 and the pre-charge relay RYp are ON and the measured current value measured by the current sensor I1 (S23).

[0045] The control unit 122 increments the parameter i (S24). The initial value of the parameter i is set to 1. The control unit 122 determines whether the parameter i has exceeded a first set value (S25). The first set value is set to a value according to the number of samplings of the current values ​​in each state of the main relays RY1 and RY2 and the pre-charge relay RYp.

[0046] If the parameter i is equal to or less than the first set value (N in S25), the process proceeds to step S22, and the processes of steps S22 to S24 are repeated. If the parameter i exceeds the first set value (Y in S25), the control unit 122 controls the main relay RY1 to be in the OFF state and the pre-charge relay RYp to be in the ON state (S26). The control unit 122 acquires a measured value of the current from the current sensor I1 (S27). The control unit 122 calculates the difference between the estimated value of the current when the main relays RY1 and RY2 are in the OFF state and the pre-charge relay RYp is in the ON state and the measured value measured by the current sensor I1 (S28).

[0047] The estimated value of the current when the main relay RY1 is in the OFF state and the pre-charge relay RYp is in the ON state is derived in advance by experiment or simulation and is registered in advance in the control unit 122. Note that the estimated value of the current in this state may be a value corrected based on the measured value of the voltage of the battery module 11 and the measured value of the temperature sensor T1.

[0048] The control unit 122 increments the parameter i (S29). The control unit 122 determines whether the parameter i has exceeded a first set value (S210). If the parameter i is equal to or less than the first set value (N in S210), the process proceeds to step S27, and the processes of steps S27 to S29 are repeated. If the parameter i has exceeded the first set value (Y in S210), the control unit 122 controls the main relays RY1 and RY2 to be in the ON state and the pre-charge relay RYp to be in the OFF state (S211). The control unit 122 acquires a measured current value from the current sensor I1 (S212). The control unit 122 calculates the difference between the estimated current value when the main relays RY1 and RY2 are in the ON state and the pre-charge relay RYp is in the OFF state and the measured current value measured by the current sensor I1 (S213).

[0049] The estimated value of the current when the main relays RY1 and RY2 are in the ON state and the pre-charge relay RYp is in the OFF state is derived in advance by experiment or simulation and is registered in advance in the control unit 122. Note that the estimated value of the current in this state may be a value corrected based on the measured value of the voltage of the battery module 11 and the measured value of the temperature sensor T1.

[0050] The control unit 122 increments the parameter i (S214). The control unit 122 determines whether the parameter i has exceeded a first set value (S215). If the parameter i is equal to or less than the first set value (N in S215), the process proceeds to step S212, and steps S212 to S214 are repeated. If the parameter i has exceeded the first set value (Y in S215), the control unit 122 calculates the average value of the differences of each sample (S216). When calculating the average value of the differences of each sample, the control unit 122 preferably normalizes each difference so that the on / off states of the main relays RY1 and RY2 and the pre-charge relay RY are the same. Note that instead of calculating the average value of multiple differences, the control unit 122 may calculate the median of multiple differences.

[0051] The control unit 122 compares the average value of the differences with a threshold value (S217). The threshold value is set to the allowable error between the estimated value and the measured value of the current sensor I1. If the average value of the differences exceeds the threshold value (Y in S217), the control unit 122 determines that the current sensor I1 is abnormal (S218).

[0052] 6 is a flowchart showing the flow of a method for detecting an abnormality in the current sensor I1 according to Example 3. When the driver turns off the power to the electric vehicle (Y in S10), the control unit 20 stops all loads connected to the battery module 11, including the inverter 2.

[0053] The control unit 122 instructs the control unit 20 on the electric vehicle side to perform PWM (Pulse Width Modulation) control of the discharge switch Sd with a duty ratio D (S31). In the flowchart of FIG. 6, the main relays RY1 and RY2 are in the ON state, and the pre-charge relay RYp is in the OFF state. The initial value of the duty ratio D is set in advance. For example, it may be set to 25%. The control unit 122 acquires a measured value of the current from the current sensor I1 (S32). The control unit 122 calculates the difference between the expected value of the current at the duty ratio D of the discharge switch Sd and the measured value measured by the current sensor I1 (S33).

[0054] The estimated value of the current at the duty ratio D of the discharge switch Sd is derived in advance by experiment or simulation and is registered in advance in the control unit 122. Note that the estimated value of the current at the duty ratio D of the discharge switch Sd may be a value corrected based on the measured value of the voltage of the battery module 11 and the measured value of the temperature sensor T1.

[0055] The control unit 122 increments the parameter i (S34). The initial value of the parameter i is set to 1. The control unit 122 determines whether the parameter i has exceeded a first set value (S15). The first set value is set to a value corresponding to the number of samplings of the current value at each duty ratio D of the discharge switch Sd.

[0056] If the parameter i is equal to or less than the first set value (N in S35), the process proceeds to step S32, and the processes of steps S32 to S34 are repeated. If the parameter i exceeds the first set value (Y in S35), the control unit 122 adds an increase value β to the duty ratio D of the discharge switch Sd (S36). Because the duty ratio D of the discharge switch Sd is changed to change the load conditions, the increase value β needs to be set to a value that significantly changes the current consumption of the discharge circuit. For example, it may be set to 25%.

[0057] The control unit 122 determines whether the duty ratio D of the discharge switch Sd exceeds a third set value (S17). The third set value is set to a value corresponding to the number of load conditions. For example, it may be set to 100%. If the duty ratio D of the discharge switch Sd is equal to or less than the third set value (N in S37), the process proceeds to step S31, and steps S31 to S36 are repeated. If the duty ratio D of the discharge switch Sd exceeds the third set value (Y in S37), the control unit 122 calculates the average value of the differences of each sample (S38). When calculating the average value of the differences of each sample, the control unit 122 preferably normalizes each difference so that the duty ratio D of the discharge switch Sd is under the same condition. Note that instead of calculating the average value of multiple differences, the control unit 122 may calculate the median of multiple differences.

[0058] The control unit 122 compares the average value of the differences with a threshold value (S39). The threshold value is set to the allowable error between the estimated value and the measured value of the current sensor I1. If the average value of the differences exceeds the threshold value (Y in S39), the control unit 122 determines that the current sensor I1 is abnormal (S310).

[0059] As described above, according to this embodiment, the soundness of the current sensor I1 mounted on the battery pack 10 can be confirmed with high accuracy and low cost. There is no need to install multiple current sensors on the power supply line, which prevents costs from increasing. Furthermore, since the test is performed when the system power supply of the electric vehicle is turned off, there is no time constraint and there is ample time to acquire a large number of current sample values. In contrast, when the test is performed during the precharge period at startup, there is less time to spare and the number of current sample values ​​is reduced. Therefore, compared to when the test is performed during the precharge period at startup, the soundness of the current sensor I1 can be determined with high accuracy based on a large number of sample values.

[0060] Furthermore, since the diagnosis is performed when the system power supply of the electric vehicle is turned off, there is no need to start the system to diagnose the current sensor I1 while the electric vehicle is parked, which reduces the number of times the system is started and suppresses an increase in the starting current.

[0061] The present disclosure has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0062] In the first embodiment, the control unit 122 changes the load conditions by changing the rotation speed of the fan 13. In the second embodiment, the control unit 122 changes the load conditions by changing the on / off states of the main relays RY1 and RY2 and the precharge relay RYp. In the third embodiment, the control unit 122 changes the load conditions by changing the duty ratio D of the discharge switch Sd. In this regard, more complex load conditions may be set by combining two or more of the three load conditions according to the first to third embodiments.

[0063] In the above-described embodiment, an example has been described in which the power supply system 1 is mounted on an electric vehicle. In this regard, the power supply system 1 may also be mounted on a stationary power storage system (including a hybrid power storage system), a small mobility device (e.g., an electric bicycle, an electric motorcycle, or an electric kick scooter), a multicopters, an electronic device (e.g., a notebook PC, a smartphone), or the like.

[0064] In the above embodiment, an example has been described in which the battery pack 10 incorporating the battery module 11 is used. In this regard, a capacitor pack incorporating a capacitor module including an electric double layer capacitor cell, a lithium ion capacitor cell, or the like may also be used. In this specification, the battery module and the capacitor module are collectively referred to as a power storage module.

[0065] The embodiment may be specified by the following items.

[0066] [Item 1] A power supply system (1) comprising: a storage module (11) for supplying current to a load (3, 13); a current sensor (I1) connected in series to the storage module (11) for measuring a value of a current flowing through the storage module (11); and a control unit (122) for acquiring a measurement value of the current from the current sensor (I1), wherein the control unit (122) changes a state of a discharge switch (Sd) included in a discharge circuit (Rd, Sd) connected in parallel with the load (3, 13) to acquire a plurality of measurement values ​​of the current from the current sensor (I1), and performs an abnormality determination of the current sensor (I1) based on the acquired plurality of measurement values.

[0067] This allows for determining whether the current sensor (I1) is abnormal at low cost and with high accuracy.

[0068] [Item 2] The power storage device further includes: a main switch (RY1, RY2) provided in a power line between the power storage module (11) and the load (3, 13); and a series circuit of a resistor (Rd) and a pre-charge switch (RYp) connected in parallel to the main switch (RY1, RY2), wherein the control unit (122) controls the discharge switch (Sd) to an on state; and acquires a plurality of current measurement values ​​from the current sensor (I1) in three states: an off state in which both the main switch (RY1, RY2) and the pre-charge switch (RYp) are both off; an off state in which the main switch (RY1, RY2) is off and the pre-charge switch (RYp) is on; and an on state in which the main switch (RY1, RY2) is on and the pre-charge switch (RYp) is off; 2. The power supply system (1) according to item 1, wherein a difference between an estimated value of a current in each state of the main switch and the precharge switch (RYp) and a measured value measured by the current sensor (I1) is calculated, and if an average value or a median value of the difference exceeds a threshold value, it is determined that an abnormality has occurred in the current sensor (I1).

[0069] According to this, by acquiring the measured current values ​​under a plurality of load conditions, it is possible to determine with high accuracy whether the current sensor (I1) is abnormal.

[0070] [Item 3] The power supply system (1) according to Item 2, wherein the control unit (122) acquires a plurality of measurement values ​​from the current sensor (I1) in each of the three states of the main switch (RY1, RY2) and the precharge switch (RYp).

[0071] This allows the number of samples of the current measurement value to be further increased.

[0072] [Item 4] The power supply system (1) according to Item 1, wherein the control unit (122) controls the discharge switch (Sd) using PWM (Pulse Width Modulation), and the control unit (122) calculates a difference between an estimated value of a current at each duty ratio of the discharge switch (Sd) and a measured value measured by the current sensor (I1), and determines that an abnormality has occurred in the current sensor (I1) when an average value or a median value of the differences exceeds a threshold value.

[0073] According to this, by acquiring the measured current values ​​under a plurality of load conditions, it is possible to determine with high accuracy whether the current sensor (I1) is abnormal.

[0074] [Item 5] The power supply system (1) according to Item 4, wherein the control unit (122) acquires a plurality of measurement values ​​from the current sensor (I1) in states of each duty ratio of the discharge switch (Sd).

[0075] This allows the number of samples of the current measurement value to be further increased.

[0076] [Item 6] The power supply system (1) according to any one of Items 1 to 5, wherein the power supply system (1) is mounted on an electric vehicle, and the control unit (122) executes an abnormality determination of the current sensor (I1) when a power source of the electric vehicle is turned off.

[0077] This makes it possible to suppress an increase in current consumption while ensuring sufficient time to determine whether the current sensor (I1) is abnormal.

[0078] [Item 7] A method for detecting an abnormality in a current sensor (I1), comprising: a step of acquiring a current measurement value from a current sensor (I1) connected in series to a storage module (11) for supplying current to a load (3, 13) and measuring a value of a current flowing through the storage module (11); and a step of changing a state of a discharge switch (Sd) included in a discharge circuit (Rd, Sd) connected in parallel with the load (3, 13) to acquire a plurality of current measurement values ​​from the current sensor (I1), and performing an abnormality determination of the current sensor (I1) based on the acquired plurality of measurement values.

[0079] This allows for determining whether the current sensor (I1) is abnormal at low cost and with high accuracy.

[0080] [Item 8] A program for detecting an abnormality in a current sensor (I1), which causes a computer to execute the following processes: a process of acquiring a current measurement value from a current sensor (I1) connected in series to a storage module (11) for supplying current to a load (3, 13) and measuring the value of a current flowing in the storage module (11); and a process of changing a state of a discharge switch (Sd) included in a discharge circuit (Rd, Sd) connected in parallel to the load (3, 13), acquiring a plurality of current measurement values ​​from the current sensor (I1), and performing an abnormality determination of the current sensor (I1) based on the acquired plurality of measurement values.

[0081] This allows for determining whether the current sensor (I1) is abnormal at low cost and with high accuracy.

[0082] REFERENCE SIGNS LIST 1 power supply system, 2 inverter, 3 motor, 10 battery pack, 11 battery module, 12 battery management device, 121 measurement unit, 122 control unit, 13 fan, I1, I2 current sensors, T1 temperature sensor, RY1, RY2 main relay, RYp precharge relay, Rp precharge resistor, C1 capacitor, Rd discharge resistor, Sd discharge switch, E1-En cells, 20 control unit.

Claims

1. A power supply system comprising: a storage module for supplying current to a load; a current sensor connected in series to the storage module for measuring the value of a current flowing through the storage module; and a control unit for acquiring a current measurement value from the current sensor, wherein the control unit changes a state of a discharge switch included in a discharge circuit connected in parallel to the load multiple times to acquire multiple current measurement values ​​from the current sensor, and performs an abnormality determination for the current sensor based on the multiple acquired measurement values.

2. The power supply system according to claim 1, further comprising: a main switch provided in a power line between the storage module and the load; and a series circuit of a resistor and a pre-charge switch connected in parallel to the main switch, wherein the control unit controls the discharge switch to an on state, acquires a plurality of current measurement values ​​from the current sensor in three states: a state in which both the main switch and the pre-charge switch are off, a state in which the main switch is off and the pre-charge switch is on, and a state in which the main switch is on and the pre-charge switch is off, calculates the difference between an assumed current value in each state of the main switch and the pre-charge switch and the measurement value measured by the current sensor, and determines that an abnormality has occurred in the current sensor if an average value or a median value of the differences exceeds a threshold value.

3. The power supply system according to claim 2, wherein the control unit obtains a plurality of measurement values ​​from the current sensor in each of the three states of the main switch and the precharge switch.

4. The power supply system according to claim 1, wherein the control unit controls the discharge switch using PWM (Pulse Width Modulation), and the control unit calculates the difference between an expected current value at each duty ratio of the discharge switch and a measured value measured by the current sensor, and determines that an abnormality has occurred in the current sensor if an average value or a median value of the differences exceeds a threshold value.

5. The power supply system according to claim 4, wherein the control unit obtains a plurality of measurement values ​​from the current sensor in each duty ratio state of the discharge switch.

6. The power supply system according to any one of claims 1 to 5, wherein the power supply system is mounted on an electric vehicle, and the control unit executes an abnormality determination for the current sensor when a power source for the electric vehicle is turned off.

7. A method for detecting an abnormality in a current sensor, comprising: a step of acquiring a current measurement value from a current sensor connected in series with a storage module for supplying current to a load, the current measurement value being measured by the current sensor, the current measurement value being measured by the current sensor, and the current measurement value being measured by the current sensor, the current measurement value being measured by the current sensor, and the current measurement value being determined to be abnormal based on the acquired measurement values.

8. A current sensor abnormality detection program that causes a computer to execute the following processes: a process of acquiring a current measurement value from a current sensor that is connected in series with a storage module for supplying current to a load and measures the value of the current flowing through the storage module; a process of changing the state of a discharge switch included in a discharge circuit connected in parallel with the load to acquire multiple current measurement values ​​from the current sensor, and performing an abnormality determination for the current sensor based on the multiple acquired measurement values.

9. A non-transitory recording medium on which the current sensor abnormality detection program according to claim 8 is recorded.

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