Battery abnormality detection system, battery abnormality detection method, and battery abnormality detection program

Abstract

An acquisition unit (341) acquires time-series data of the voltages of a plurality of single cells connected in series or a plurality of parallel cells in a state where an assembled battery system (31) is charged to a target voltage or in a state where either the single cells connected in series or the parallel cells are charged to the target voltage. A determination unit (342) determines that a micro short circuit has occurred in a single cell or parallel cell of which the voltage is transitioning in a decreasing direction after having been charged to the acquired target voltage.

Description

Battery abnormality detection system, battery abnormality detection method, and battery abnormality detection program

[0001] The present disclosure relates to a battery abnormality detection system, a battery abnormality detection method, and a battery abnormality detection program that detect a micro-short circuit in a battery pack system.

[0002] The number of devices equipped with multi-series battery cells (hereinafter simply referred to as cells), such as EVs and notebook PCs, is increasing, and many of these devices use battery packs that include assembled battery systems made up of multi-series and multi-parallel cells. When lithium-ion cells are used, a short circuit can lead to a fire, so it is necessary to detect abnormal cells early, especially in battery packs that use lithium-ion cells.

[0003] Minor short circuits in a multi-parallel battery pack are often not noticed until the voltage difference becomes large, making early detection difficult. One method for detecting internal cell short circuits is to determine that a short circuit has occurred when the difference between a reference voltage calculated from the current integration value or SOC (State of Charge) and the measured voltage of a parallel cell exceeds a set value. Another method involves determining that a parallel cell has a voltage difference with other parallel cells connected in series that is greater than a set value as a shorted cell (see, for example, Patent Document 1). However, the voltage variation between parallel cells connected in series can increase due to factors other than an internal short circuit. In such cases, determining whether or not an internal short circuit exists based solely on the voltage difference can result in erroneous detection.

[0004] Another approach is to smooth the voltages of parallel cells during charging and discharging and determine a short circuit when the voltage difference between the parallel cells exceeds a set value. However, this method makes it difficult to adjust the degree of smoothing, and insufficient or excessive smoothing can result in false positives or oversights.

[0005] JP 2011-135656 A

[0006] The present disclosure has been made in view of these circumstances, and its purpose is to provide a technology for detecting micro-short circuits in cells at an early stage with high accuracy.

[0007] In order to solve the above problems, a battery abnormality detection system according to one aspect of the present disclosure is a battery abnormality detection system that detects an abnormality in an assembled battery system that includes a plurality of unit cells connected in series or a plurality of parallel cells connected in series, and includes: an acquisition unit that acquires time-series data on the voltages of the unit cells or the parallel cells when the assembled battery system is charged to a target voltage or when either the unit cells or the parallel cells are charged to a target voltage; and a determination unit that determines that a micro-short circuit has occurred in a unit cell or parallel cell whose voltage when charged to the target voltage is decreasing.

[0008] Any combination of the above components, and conversion of the expression of the present disclosure into an apparatus, system, method, computer program, etc., are also valid aspects of the present disclosure.

[0009] According to the present disclosure, micro-short circuits in cells can be detected early and with high accuracy.

[0010] FIG. 1 is a diagram for explaining a battery-equipped device according to embodiment 1. FIG. 2 is a diagram showing the configuration of a battery pack system including a plurality of unit cells connected in series. FIG. 3 is a diagram showing the configuration of a battery pack system including a plurality of parallel cells connected in series. FIG. 4 is a diagram showing an example of transition data of maximum cell voltage and minimum cell voltage in a battery pack system. FIG. 5 is a diagram showing an example of transition data of each cell voltage after a micro-short circuit occurs in a 3-series battery pack system. FIG. 6 is a diagram showing the cell voltage when fully charged is extracted from the transition data of cell voltages shown in FIG. 4.

[0011] FIG. 1 is a diagram illustrating a battery-equipped device 2 according to a first embodiment. The battery-equipped device 2 according to the first embodiment is a device equipped with a chargeable and dischargeable battery pack 30. Examples of the battery-equipped device 2 include consumer information devices (e.g., PCs, tablets, smartphones), home appliances (e.g., cleaning robots), electric cars, electric motorcycles, electric bicycles, electric kick scooters, and multicopters (drones). In the following description of this embodiment, a notebook PC is assumed.

[0012] The battery-equipped device 2 includes a control unit 21, a load unit 22, a charging unit 23, and a battery pack 30. The control unit 21 controls the entire battery-equipped device 2. The functions of the control unit 21 can be realized by a combination of hardware and software resources, or by hardware resources alone. Hardware resources that can be used include a CPU, ROM, RAM, GPU (Graphics Processing Unit), NPU (Neural Network Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and other LSIs. Software resources that can be used include programs such as an operating system and applications.

[0013] The load unit 22 is a general term for components (excluding the control unit 21 and the charging unit 23) that consume power in the battery-equipped device 2. The charging unit 23 is connected to the commercial power system 4 via an AC adapter (not shown). The AC adapter converts an AC voltage of 100 / 200 V input from the commercial power system 4 into a DC voltage of about 5-20 V and outputs it.

[0014] Charging unit 23 includes a DC / DC converter (e.g., a switching regulator) that controls the voltage or current of the DC power supplied from the AC adapter in accordance with a voltage command value or a current command value supplied from control unit 21, and outputs the DC power of the voltage or current specified by the command value to at least one of load unit 22 and battery pack 30.

[0015] The battery pack 30 includes a battery assembly system 31 and a battery management device 32. The battery assembly system 31 includes a plurality of unit cells connected in series or a plurality of parallel cells.

[0016] 2A is a diagram showing the configuration of a battery pack system 31 including a plurality of unit cells E1-Em connected in series. FIG. 2B is a diagram showing the configuration of a battery pack system 31 including a plurality of parallel cells Eb1-Ebm connected in series. Each parallel cell Eb1-Ebm includes a plurality of unit cells E1a-E1n-Ema-Emn connected in parallel.

[0017] The cells may be lithium-ion battery cells, nickel-metal hydride battery cells, lead battery cells, etc. In the following description, we will assume an example in which lithium-ion battery cells (nominal voltage: 3.6-3.7 V) are used. The number of single cells or parallel cells connected in series is determined according to the voltage of the load section 22.

[0018] A switch SW1 that switches between electrical continuity with the load unit 22 or the charging unit 23 is inserted in a power line connecting the battery pack system 31 to the load unit 22 or the charging unit 23. A semiconductor switch or a relay can be used as the switch SW1.

[0019] The battery management device 32 includes a measurement unit 33, a control unit 34, and a non-volatile memory unit 35. The measurement unit 33 is configured with an AFE (Analog Front End) IC or an ASIC (Application Specific Integrated Circuit). The control unit 34 is configured with a microcontroller. The control unit 34 includes an acquisition unit 341 and a determination unit 342. The non-volatile memory unit 35 is configured with an EEPROM (Electrically Erasable Programmable Read Only Memory) or a NAND flash memory. Note that if the microcontroller has a built-in EEPROM, the non-volatile memory unit 35 can be omitted.

[0020] The measurement unit 33 is connected to each node of the multiple unit cells E1-Em or parallel cells Eb1-Ebm connected in series by multiple voltage measurement lines, and measures the voltage between each two adjacent voltage measurement lines to measure the voltage of each unit cell E1-Em or parallel cell Eb1-Ebm.

[0021] The measurement unit 33 includes a multiplexer and an A / D converter. The multiplexer outputs the voltages of the multiple single cells E1-Em or parallel cells Eb1-Ebm 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 33 transmits the converted digital voltage values ​​of the single cells E1-Em or parallel cells Eb1-Ebm to the control unit 34 via the serial communication interface.

[0022] The measurement unit 33 measures the current flowing through the battery pack system 31. A shunt resistor Rs is connected to a power line connecting the battery pack system 31 to the load unit 22 or the charging unit 23. A differential amplifier (not shown) amplifies the voltage across the shunt resistor Rs and outputs it to an A / D converter in the measurement unit 33. The A / D converter converts the analog voltage indicating the current flowing through the battery pack system 31, which is input from the differential amplifier, into a digital value. The measurement unit 33 transmits the current value converted into a digital value to the control unit 34 via a serial communication interface.

[0023] A plurality of temperature sensors T1-Tm (e.g., thermistors) are installed on the surface of the battery pack system 31. The divided voltages of each temperature sensor T1-Tm and voltage dividing resistors (not shown) are input to a measurement unit 33. An A / D converter in the measurement unit 33 converts the input analog voltages indicating the temperatures detected by each temperature sensor T1-Tm into digital values. The measurement unit 33 transmits the converted digital temperature values ​​detected by each temperature sensor T1-Tm to a control unit 34 via a serial communication interface.

[0024] The control unit 34 manages the state of the single cells E1-Em or the parallel cells Eb1-Ebm based on the voltage values ​​of the individual single cells E1-Em or the parallel cells Eb1-Ebm, the current values ​​flowing through the battery pack system 31, and the temperature values ​​detected by the individual temperature sensors T1-Tm received from the measurement unit 33. When the control unit 34 detects overcharge, overdischarge, overcurrent, abnormally high temperature, or abnormally low temperature, it sends a shut-off signal for the switch SW1 to the measurement unit 33 to turn off the switch SW1.

[0025] The control unit 34 executes programs such as firmware within the microcontroller to achieve the following functions. The control unit 34 estimates the SOC by combining the OCV method and the current integration method. The OCV method is a method for estimating 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 34 at the time of shipment.

[0026] 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.

[0027] In the first embodiment, a battery abnormality detection system is implemented in the control unit 34 of the battery management device 32. The acquisition unit 341 records the voltages of the plurality of unit cells E1-Em or parallel cells Eb1-Ebm when the assembled battery system 31 is charged to the target voltage, which are acquired from the measurement unit 33, in the non-volatile memory unit 35. Note that instead of the state when the assembled battery system 31 is charged to the target voltage, the voltages of the plurality of unit cells E1-Em or parallel cells Eb1-Ebm when any of the unit cells or parallel cells is charged to the target voltage may be recorded.

[0028] The target voltage may be the target voltage during CV charging in CC-CV charging. Specifically, the target voltage may be the fully charged voltage (the voltage when the SOC is 100%) or a specified voltage of 50% or higher. In the case of hybrid cars, the specified voltage is set to 50% to ensure sufficient capacity to accept regenerative charging. Furthermore, even in pure EVs, there are some models that can only be charged up to 95% to prevent overcharging.

[0029] In this embodiment, the purpose is to detect a micro-short circuit in a cell, but when comparing a voltage drop due to a short circuit from a high voltage state with a voltage drop due to a short circuit from a low voltage state, the higher the voltage, the easier it is for a short circuit current to flow, so the degree of voltage drop tends to be smaller in the latter case. Therefore, it is desirable to detect a short circuit using data from a voltage state that is as high as possible, and it is desirable that the target voltage mentioned above is a voltage of at least 50% SOC or higher.

[0030] The acquisition unit 341 acquires time-series data of the voltages of the plurality of single cells E1-Em or parallel cells Eb1-Ebm in a state where they have been charged to the target voltage at a predetermined timing for determining whether a short circuit has occurred from the non-volatile memory unit 35. The predetermined timing for determining whether a short circuit has occurred may be the timing at which charging is completed when the charging has been completed to the target voltage.

[0031] The determination unit 342 determines that a single cell or a parallel cell (hereinafter, the single cell and the parallel cell will be collectively referred to as a cell as appropriate) whose voltage is decreasing when charged to the acquired target voltage is a cell in which a micro-short circuit has occurred. A specific example will be described below.

[0032] 3 is a diagram showing an example of transition data of the maximum cell voltage and minimum cell voltage in the battery pack system 31. The maximum cell voltage and minimum cell voltage at full charge in the section before the circled section are approximately the same, and it is estimated that no cells are micro-short-circuited. On the other hand, the voltage difference between the maximum cell voltage and minimum cell voltage at full charge in the circled section gradually increases, and it is estimated that the cell with the minimum voltage is micro-short-circuited.

[0033] Fig. 4 shows an example of data on the transition of cell voltages after a micro-short circuit occurs in a three-series battery pack system 31. Fig. 5 shows the cell voltages at full charge extracted from the data on the transition of cell voltages shown in Fig. 4. The three cell voltages shown in Fig. 4 are shifted by a predetermined time for each cell to avoid overlapping of the transition lines. The examples shown in Figs. 4 and 5 show a case where a micro-short circuit occurs in the third cell E3.

[0034] The determination unit 342 determines whether or not a micro-short circuit exists in each cell based on the cell voltage during a set interval ΔT (time T1-time T2) shown in FIG. 5 . For example, the determination unit 342 determines that a cell in which the voltage at full charge has been decreasing for a set number of consecutive times or more is experiencing a micro-short circuit. The determination unit 342 may also determine that a cell in which the voltage at full charge has been decreasing for a set number of consecutive times or more in a relative comparison with other cells is experiencing a micro-short circuit. Here, a cell in which the voltage has been decreasing in a relative comparison with other cells refers to a cell in which the difference in the decreasing direction from a representative value (e.g., average value, median value) of the voltages of the multiple cells E1-E3 connected in series is increasing.

[0035] The determination unit 342 may also linearly regress the voltage at full charge for each of the multiple cells E1-E3, and determine that a cell whose slope deviates by a set value or more in the negative direction from a line with a slope of 0 or from the slope of the regression line of another cell is experiencing a micro-short circuit. In FIG. 5 , the slope of the regression line for the voltage of the first cell E1 over the set interval ΔT is approximately horizontal (approximately 0), and the slope of the regression line for the voltage of the second cell E2 over the set interval ΔT is also approximately horizontal (approximately 0). In contrast, the slope of the regression line for the voltage of the third cell E3 over the set interval ΔT is a negative value that slopes downward to the right. Therefore, the third cell E3 is determined to be experiencing a micro-short circuit.

[0036] 6 is a flowchart showing the flow of the battery abnormality detection process performed by the battery management device 32 according to embodiment 1. The acquisition unit 341 records the cell voltages at full charge obtained from the measurement unit 33 in the non-volatile storage unit 35 (S10). When the timing for short circuit detection process arrives (Y in S11), the acquisition unit 341 acquires time-series data of the cell voltages at full charge from the non-volatile storage unit 35 (S12).

[0037] The determination unit 342 determines whether or not there is a cell whose voltage is decreasing (S13). If there is a cell whose voltage is decreasing (Y in S13), the determination unit 342 determines that the cell is a cell that is micro-short circuited (S14). The determination unit 342 issues an alert to the user by turning on a warning lamp (not shown) or the like (S15). If there is no cell whose voltage is decreasing (N in S13), the processes of steps S14 and S15 are skipped. The processes of steps S10 to S15 described above are repeatedly executed (N in S16) until operation of the battery pack 30 is stopped (Y in S16).

[0038] As described above, according to the first embodiment, it is possible to detect a micro-short circuit in a cell early with high accuracy. That is, it is less susceptible to the influence of voltage variations between cells and does not require smoothing, so that erroneous detection can be reduced. Furthermore, even if a micro-short circuit occurs in a cell with a relatively high voltage, it is possible to detect the micro-short circuit early.

[0039] 7 is a diagram showing another example of cell voltages at full charge extracted from data on the transition of each cell voltage after a micro-short circuit occurs in a three-series battery pack system 31. The example shown in Fig. 7 also shows a case where a micro-short circuit occurs in the third cell E3, but unlike the example shown in Fig. 5, the micro-short circuit occurs when the voltage of the third cell E3 is relatively higher than the voltages of the other cells E1 and E2. In this case, in section a immediately after the micro-short circuit occurs, the voltage difference between the maximum and minimum cell voltages transitions in a decreasing direction.

[0040] In the conventional method of determining the occurrence of a micro-short circuit when the voltage difference between cells increases, it takes time to detect a micro-short circuit. In contrast, in this embodiment, a micro-short circuit is detected when the cell voltage is decreasing, making it possible to detect it at an early stage.

[0041] Furthermore, according to this embodiment, since it is only necessary to record the voltage data when the battery is charged to the target voltage, the amount of data to be recorded can be significantly reduced compared to methods that require recording voltage data over the entire period. This allows the use of a non-volatile memory unit 35 with a relatively low capacity, thereby reducing implementation costs. Furthermore, by using only the voltage data when the battery is charged to the target voltage, the effects of variations in cell voltage during charging and discharging can be eliminated.

[0042] 8 is a diagram for explaining a battery-equipped device 2 according to embodiment 2. In embodiment 1, an example was described in which a battery abnormality detection system is implemented in a battery management device 32. In contrast, in embodiment 2, an example is described in which a battery abnormality detection system is implemented in a cloud server.

[0043] In the battery-equipped device 2 according to the second embodiment, the non-volatile memory unit 35 for recording voltage data when the target voltage is reached can be omitted. In the battery-equipped device 2 according to the second embodiment, a communication unit 24 is added. The communication unit 24 is an external communication interface (for example, a network interface card (NIC)) for connecting to an external network 5 by wire or wirelessly.

[0044] The control unit 34 transmits battery data including the voltage, current, temperature, and SOC of each cell of the battery pack system 31 to the control unit 21 via the network inside the device. The control unit 21 accesses the network 5 via the communication unit 24 and transmits the battery data received from the control unit 34 of the battery pack 30 to the battery abnormality detection system 1 at a predetermined transmission cycle (for example, every 10 seconds or every 1 minute).

[0045] The network 5 is a general term for communication paths such as the Internet, a dedicated line, and a Virtual Private Network (VPN), and the communication medium and protocol are not important. Examples of communication media that can be used include a wired LAN, a wireless LAN, a mobile phone network, an optical fiber network, an ADSL network, and a CATV network. Examples of communication protocols that can be used include TCP (Transmission Control Protocol) / IP (Internet Protocol), UDP (User Datagram Protocol) / IP, and Ethernet (registered trademark).

[0046] The battery abnormality detection system 1 is a system for estimating and analyzing the state of a battery pack 30 mounted in a battery-equipped device 2. In the second embodiment, the battery abnormality detection system 1 is constructed on a cloud server installed in a data center managed by a cloud service provider. A battery analysis service provider that provides an analysis service for the battery pack 30 uses the cloud server by entering into a contract with the cloud service provider. The battery abnormality detection system 1 may also be constructed on the battery analysis service provider's own server installed in its own facility or data center.

[0047] 9 is a diagram showing an example of the configuration of a battery abnormality detection system 1 according to embodiment 2. The battery abnormality detection system 1 includes a control unit 11, a storage unit 12, and a communication unit 13. The communication unit 13 is an external communication interface for connecting to a network 5 via a wired or wireless connection.

[0048] The control unit 11 includes an acquisition unit 111 and a determination unit 112. The functions of the control unit 11 can be realized by a combination of hardware and software resources, or by hardware resources alone. Examples of hardware resources that can be used include a CPU, ROM, RAM, GPU, NPU, ASIC, FPGA, and other LSIs. Examples of software resources that can be used include programs such as an operating system and applications.

[0049] The storage unit 12 includes a non-volatile recording medium such as an HDD or SSD, and stores various data. The storage unit 12 includes a battery data holding unit 121. The acquisition unit 111 acquires battery data of the battery pack 30 installed in the battery-equipped device 2 from the battery-equipped device 2 via the network 5. The acquisition unit 111 stores the acquired battery data in the battery data holding unit 121. Other functions of the acquisition unit 111 and the determination unit 112 are similar to the functions of the acquisition unit 341 and the determination unit 342 of the control unit 34 of the battery management device 32 according to the first embodiment.

[0050] As described above, according to the second embodiment, the same effects as those of the first embodiment can be achieved. Furthermore, according to the second embodiment, the battery abnormality detection process according to the present disclosure can be applied to a battery pack 30 equipped with an existing battery management device 32 that does not have the battery abnormality detection system according to the present disclosure implemented therein. Also, short circuit detection can be added to a comprehensive battery analysis service that uses a cloud service and includes life prediction and the like.

[0051] 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.

[0052] In the above-described embodiment, the determination unit 342 determines that a cell whose voltage at full charge has been decreasing for a set number of consecutive times or more is experiencing a micro-short circuit. The determination unit 342 may adaptively change the set number of times depending on the frequency of charging to the target voltage. Specifically, the lower the frequency of charging to the target voltage, the lower the set number of times. For example, if the battery-equipped device 2 is charged once a week to the target voltage, the set number of times may be set to three. If the battery-equipped device 2 is charged daily to the target voltage, the set number of times may be set to ten.

[0053] The embodiment may be specified by the following items.

[0054] [Item 1] A battery abnormality detection system (34) for detecting an abnormality in an assembled battery system (31) including a plurality of unit cells (E1-Em) connected in series or a plurality of parallel cells (Eb1-Ebm) connected in series, the battery abnormality detection system (34) comprising: an acquisition unit (341) that acquires time-series data of the voltages of the plurality of unit cells (E1-Em) or the plurality of parallel cells (Eb1-Ebm) when the assembled battery system (31) is charged to a target voltage or when either the unit cells (E1-Em) or the parallel cells (Eb1-Ebm) are charged to a target voltage; and a determination unit (342) that determines that a micro-short circuit has occurred in a unit cell (E1-Em) or a parallel cell (Eb1-Ebm) whose acquired voltage in the state charged to the target voltage is trending downward.

[0055] This allows for early detection of a micro-short circuit in a single cell (E1-Em) or parallel cell (Eb1-Ebm) with high accuracy.

[0056] [Item 2] The battery abnormality detection system (34) according to Item 1, wherein the determination unit (342) determines that a micro-short circuit has occurred in a single cell (E1-Em) or a parallel cell (Eb1-Ebm) whose voltage in a state where it has been charged to the target voltage has been decreasing for a set number of consecutive times or more.

[0057] This allows for highly accurate detection of micro-short circuits.

[0058] [Item 3] The battery abnormality detection system (34) according to Item 1, wherein the determination unit (342) linearly regresses the voltage in a state charged to the target voltage for each of the plurality of single cells (E1-Em) or the plurality of parallel cells (Eb1-Ebm), and determines that a micro-short circuit has occurred in a single cell (E1-Em) or a parallel cell (Eb1-Ebm) for which a slope deviates in a negative direction by a set value or more.

[0059] This allows for highly accurate detection of micro-short circuits.

[0060] [Item 4] The battery abnormality detection system (34) according to any one of Items 1 to 3, wherein the determination unit determines that a micro-short circuit has occurred in a relative comparison with other single cells (E1-Em) or parallel cells (Eb1-Ebm).

[0061] This allows for highly accurate detection of micro-short circuits.

[0062] [Item 5] The battery abnormality detection system (34) according to any one of Items 1 to 3, wherein the target voltage is a fully charged voltage.

[0063] According to this, by using voltage data in a fully charged state, the influence of a micro-short circuit can be more accurately grasped.

[0064] [Item 6] A battery abnormality detection method for detecting an abnormality in an assembled battery system (31) including a plurality of unit cells (E1-Em) connected in series or a plurality of parallel cells (Eb1-Ebm) connected in series, the battery abnormality detection method comprising the steps of: acquiring time-series data of the voltages of the plurality of unit cells (E1-Em) or the plurality of parallel cells (Eb1-Ebm) when the assembled battery system (31) is charged to a target voltage, or when any of the unit cells (E1-Em) or the parallel cells (Eb1-Ebm) is charged to a target voltage; and determining that a micro-short circuit has occurred in a unit cell (E1-Em) or a parallel cell (Eb1-Ebm) whose acquired voltage in a state charged to the target voltage is trending downward.

[0065] This allows for early detection of a micro-short circuit in a single cell (E1-Em) or parallel cell (Eb1-Ebm) with high accuracy.

[0066] [Item 7] A battery abnormality detection program for detecting an abnormality in an assembled battery system (31) including a plurality of unit cells (E1-Em) connected in series or a plurality of parallel cells (Eb1-Ebm) connected in series, the program causing a computer to execute the following steps: acquiring time-series data on the voltages of the plurality of unit cells (E1-Em) or the plurality of parallel cells (Eb1-Ebm) when the assembled battery system (31) is charged to a target voltage, or when any of the unit cells (E1-Em) or the parallel cells (Eb1-Ebm) is charged to a target voltage; and determining that a micro-short circuit has occurred in a unit cell (E1-Em) or a parallel cell (Eb1-Ebm) whose acquired voltage in a state charged to the target voltage is decreasing.

[0067] This allows for early detection of a micro-short circuit in a single cell (E1-Em) or parallel cell (Eb1-Ebm) with high accuracy.

[0068] REFERENCE SIGNS LIST 1 Battery abnormality detection system, 2 Battery-equipped device, 4 Commercial power system, 5 Network, 21 Control unit, 22 Load unit, 23 Charging unit, 24 Communication unit, 30 Battery pack, 31 Assembled battery system, 32 Battery management device, 33 Measurement unit, 34 Control unit, 341 Acquisition unit, 342 Determination unit, 35 Non-volatile memory unit, E1-Em Cell, Rs Shunt resistor, SW1 Switch, 11 Control unit, 111 Acquisition unit, 112 Determination unit, 12 Memory unit, 121 Battery data retention unit, 13 Communication unit.

Claims

1. A battery abnormality detection system for detecting an abnormality in a battery pack system including a plurality of single cells connected in series or a plurality of parallel cells connected in series, the battery abnormality detection system comprising: an acquisition unit that acquires time-series data of voltages of the plurality of single cells or the plurality of parallel cells in a state where the battery pack system is charged to a target voltage or in a state where any one of the single cells or the parallel cells is charged to the target voltage; and a determination unit that determines that a single cell or a parallel cell in which the voltage in the state of being charged to the acquired target voltage is shifting in a decreasing direction has a micro short circuit.

2. The battery abnormality detection system according to claim 1, wherein the determination unit determines that a single cell or a parallel cell in which the voltage in the state of being charged to the target voltage is shifting in a decreasing direction continuously for a set number of times or more has a micro short circuit.

3. The battery abnormality detection system according to claim 1, wherein the determination unit performs linear regression on the voltage in the state of being charged to the target voltage for each of the plurality of single cells or the plurality of parallel cells, and determines that a single cell or a parallel cell in which the slope deviates by a set value or more in the negative direction has a micro short circuit.

4. The battery abnormality detection system according to any one of claims 1 to 3, wherein the determination unit determines that a micro short circuit has occurred in a relative comparison with other single cells or parallel cells.

5. The battery abnormality detection system according to any one of claims 1 to 3, wherein the target voltage is a full charge voltage.

6. A battery abnormality detection method for detecting an abnormality in a battery pack system including a plurality of single cells connected in series or a plurality of parallel cells connected in series, the battery abnormality detection method comprising: a step of acquiring time-series data of voltages of the plurality of single cells or the plurality of parallel cells in a state where the battery pack system is charged to a target voltage or in a state where any one of the single cells or the parallel cells is charged to the target voltage; and a step of determining that a single cell or a parallel cell in which the voltage in the state of being charged to the acquired target voltage is shifting in a decreasing direction has a micro short circuit.

7. A battery abnormality detection program for detecting an abnormality in a battery pack system including a plurality of single cells connected in series or a plurality of parallel cells connected in series, the program causing a computer to execute: a process of acquiring time-series data of voltages of the plurality of single cells or the plurality of parallel cells in a state where the battery pack system is charged to a target voltage, or in a state where any one of the single cells or the parallel cells is charged to the target voltage; and a process of determining that a single cell or a parallel cell in which the voltage in the state of being charged to the acquired target voltage is changing in a decreasing direction has a micro short circuit.

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