Battery system

Abstract

In a battery system comprising multiple battery packs connected in parallel, the reliability of the detection values ​​of the current detectors placed for each battery pack is improved. [Solution] Each battery pack B includes first and second current detectors 24 and 26 that detect the current flowing through the battery stack 20. If the detected values ​​of the first and second current detectors 24 and 26 in one battery pack B do not match, the control device 30 operates the DC / DC converter 1 corresponding to each battery pack B to exchange power between that battery pack B and the other battery pack B. While the DC / DC converter 1 is operating, the control device 30 compares the detected values ​​of the first and second current detectors 24 and 26 in one battery pack B with the detected value of the first current detector 24 in the other battery pack B, and selects a normal current detector from the first and second current detectors 24 and 26 in one battery pack B.

Description

Technical Field

[0001] The present disclosure relates to a battery system, and more particularly, to a technique for detecting an abnormality of a current detector disposed in a battery system configured to include a plurality of battery packs connected in parallel.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2020-16493 (Patent Document 1) discloses a current measurement device including three or more current sensors that measure the current of a battery. The current measurement device includes an average value calculation unit that calculates an average value of the measurement values of the three or more current sensors and uses the calculated average value as the current of the battery. Further, the current measurement device includes a failure determination unit that compares the measurement values of the three or more current sensors with each other and determines that a current sensor that has measured a measurement value whose difference from the measurement value of another current sensor among the three or more current sensors is equal to or greater than a threshold value is malfunctioning.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a battery system having a plurality of battery packs connected in parallel, a plurality of DC / DC converters are provided corresponding to the plurality of battery packs. In such a battery system, a current detector is provided for each battery pack, and each DC / DC converter controls the charge and discharge of the corresponding battery pack based on the detection value of the current detector. In the entire battery system, a plurality of current detectors are arranged.

[0005] In the above-described battery system, the detected values ​​of multiple current detectors may differ due to variations in control between multiple DC / DC converters. Therefore, as described in Patent Document 1, it is not possible to determine a fault in a current detector by comparing the detected values ​​of multiple current detectors. Consequently, there are concerns about the low reliability of the detected values ​​of multiple current detectors.

[0006] This disclosure was made to solve these problems, and the purpose of this disclosure is to improve the reliability of the detection values ​​of current detectors placed for each battery pack in a battery system comprising multiple battery packs connected in parallel. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, a battery system that charges and discharges with an external system comprises a plurality of battery packs connected in parallel to each other with the external system, a plurality of DC / DC converters, and a control device that controls the plurality of DC / DC converters. The plurality of DC / DC converters are provided corresponding to each of the plurality of battery packs, and each performs DC voltage conversion between the corresponding battery pack and the external system. Each of the plurality of battery packs includes a battery stack, a first current detector for detecting the current flowing through the battery stack, and a second current detector connected in series with the first current detector for detecting the current flowing through the battery stack.

[0008] If the detected values ​​of the first current detector and the second current detector do not match in any of the multiple battery packs, the control unit operates the DC / DC converters corresponding to each of the battery packs so that power is transferred between the two battery packs. While the DC / DC converters are operating, the control unit selects a normal current detector from the first and second current detectors in the battery pack by comparing the detected values ​​of the first and second current detectors in the battery pack with the detected value of the first current detector in the other battery pack. [Effects of the Invention]

[0009] According to this disclosure, in a battery system comprising multiple battery packs connected in parallel, the reliability of the detection values ​​of current detectors placed for each battery pack can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a battery system according to an embodiment of the present disclosure. [Figure 2] This is a diagram showing the configuration of a battery module. [Figure 3] This is a diagram illustrating the abnormality detection mode of the battery system. [Figure 4] This is a flowchart illustrating the procedure for detecting abnormalities in the current detector using a control device. [Figure 5] This flowchart illustrates a modified example of the abnormality detection process for a current detector by a control device. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described in detail below with reference to the drawings. The same or corresponding parts in the drawings will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0012] Figure 1 is a schematic diagram of a battery system according to this embodiment. As shown in Figure 1, the battery system 100 according to this embodiment is connected to an external system 2 by a power line L. The battery system 100 can be powered by the external system 2 and can also discharge to the external system 2. The battery system 100 is applicable, for example, to a stationary energy storage system installed at a consumer's home.

[0013] The battery system 100 comprises a plurality of battery modules BM1 to BM3, a plurality of sub-relays SR1 to SR3, and a control device 30. Hereinafter, battery modules BM1 to BM3 will also be collectively referred to as "battery module BM," and sub-relays SR1 to SR3 will also be collectively referred to as "sub-relay SR." In the example in Figure 1, the battery system 100 comprises three battery modules BM and three sub-relays SR, but the number of each battery module BM and sub-relay SR is arbitrary and may be one.

[0014] Multiple battery modules BM1 to BM3 are connected in parallel to each other to the external system 2. Multiple sub-relays SR1 to SR3 are provided, each corresponding to one of the battery modules BM1 to BM3. The sub-relays SR are controlled by the control device 30 to connect or disconnect the corresponding battery module BM from the external system 2. In one scenario, when the battery system 100 is started up, the sub-relay SR is turned on, and the corresponding battery module BM is connected to the external system 2. If a failure occurs in the corresponding battery module BM, the sub-relay SR is turned off, and the corresponding battery module BM is disconnected from the external system 2.

[0015] The battery module BM1 includes multiple battery packs BA to BC and multiple DC / DC converters 1A to 1C. Hereafter, battery packs BA to BC will also be collectively referred to as "battery pack B," and DC / DC converters 1A to 1C will also be collectively referred to as "DC / DC converter 1." In the example in Figure 1, the battery module BM1 includes three battery packs B and three DC / DC converters 1, but the number of each of the battery packs B and DC / DC converters 1 can be multiple.

[0016] Multiple battery packs BA to BC are connected in parallel to each other to the external system 2 via sub-relay SR1. Battery pack B includes a battery stack.

[0017] Multiple DC / DC converters 1A to 1C are provided, each corresponding to one of the multiple battery packs BA to BC. DC / DC converter 1 controls the charging and discharging of the corresponding battery pack B by performing DC voltage conversion between the corresponding battery pack B and the external system 2. Specifically, DC / DC converter 1 is composed of a boost circuit and a buck circuit. The boost circuit boosts the DC voltage of the corresponding battery pack B and controls the discharge of the corresponding battery pack B by outputting the boosted voltage to the external system 2. The buck circuit steps down the DC voltage from the external system 2 and controls the charging of the corresponding battery pack B by outputting the bucked voltage to the corresponding battery pack B. The boost circuit and buck circuit are implemented, for example, by a bidirectional chopper.

[0018] Although not shown in the diagram, the configurations of battery modules BM2 and BM3 are the same as those of battery module BM1.

[0019] The external system 2 is composed of a PCS (Power Conditioning System) 3, a power grid (PG) 4, a photovoltaic power generation device (PV) 5, a load 6, and an EMS (Energy Management System) 7. The PCS 3 includes a power conversion device capable of both AC (alternating current) / DC (direct current) conversion and DC / AC conversion. The PCS 3, for example, converts the DC power from the photovoltaic power generation device 5 or the battery system 100 into AC power and supplies it to the load 6. The load 6 is an electrical product installed in a consumer's home, such as an air conditioner and lighting fixtures. The PCS 3 exchanges AC power with the power grid 4. The power grid 4 is not limited to a large-scale power grid maintained as infrastructure and may be a microgrid.

[0020] The EMS 7 collaborates with the PCS 3 to manage the energy usage situation in the consumer's home. The EMS 7 includes HEMS (Home EMS), BEMS (Building EMS), FEMS (Factory EMS), etc. The EMS 7 includes a processor and a memory.

[0021] The control device 30 includes a processor and a memory, receives commands from the EMS 7, and controls the battery system 100. The control device 30 controls a plurality of sub-relays SR1 to SR3 and also controls a plurality of DC / DC converters 1A to 1C in each battery module BM.

[0022] Figure 2 shows the configuration of battery module BM. Figure 2 shows the configuration of battery module BM1 as a representative example. As shown in Figure 2, DC / DC converter 1A includes a bidirectional chopper 10A, voltage detectors 12A and 14A, and an MG-ECU (Motor Generator-Electronic Control Unit) 16A. DC / DC converter 1B includes a bidirectional chopper 10B, voltage detectors 12B and 14B, and an MG-ECU 16B. DC / DC converter 1C includes a bidirectional chopper 10C, voltage detectors 12C and 14C, and an MG-ECU 16C. Hereafter, bidirectional choppers 10A to 10C will be collectively referred to as "bidirectional chopper 10", voltage detectors 12A to 12C will be collectively referred to as "voltage detector 12", and voltage detectors 14A to 14C will be collectively referred to as "voltage detector 14".

[0023] The bidirectional chopper 10 is a well-known type that includes multiple semiconductor switching elements. In the example shown in Figure 2, the bidirectional chopper 10 includes a reactor L1 as an energy storage element, two semiconductor switching elements Q1 and Q2 connected in series, and a smoothing capacitor C1. The bidirectional chopper 10 boosts the DC voltage of the corresponding battery pack B and outputs the boosted voltage to the external system 2. The bidirectional chopper 10 also steps down the DC voltage from the external system 2 and outputs the stepped-down voltage to the corresponding battery pack B.

[0024] Voltage detector 14 detects the voltage of the bidirectional chopper 10 before boosting (the DC voltage of battery pack B) and outputs a signal indicating the detected value. Voltage detector 12 detects the boosted voltage, which is the voltage of the bidirectional chopper 10 after boosting, and outputs a signal indicating the detected value.

[0025] The MG-ECU16 is a device that controls communication between the bidirectional chopper 10 and the control device 30, and includes a processor and memory. The MG-ECU16 transmits the output signals of the voltage detectors 12 and 14 to the control device 30. The MG-ECU16 also receives control signals from the control device 30 to control the bidirectional chopper 10. The bidirectional chopper 10 performs DC voltage conversion according to the control signals from the control device 30.

[0026] Battery pack BA includes a battery stack 20A, a relay 22A, current detectors 24A and 26A, a voltage detector 27A, and a battery ECU 28A. Battery pack BB includes a battery stack 20B, a relay 22B, current detectors 24B and 26B, a voltage detector 27B, and a battery ECU 28B. Battery pack BC includes a battery stack 20C, a relay 22C, current detectors 24C and 26C, a voltage detector 27C, and a battery ECU 28C. Hereafter, battery stacks 20A to 20C will also be collectively referred to as "battery stack 20," and relays 22A to 22C will also be collectively referred to as "relay 22." Current detectors 24A to 24C are collectively referred to as "current detector 24," current detectors 26A to 26C are collectively referred to as "current detector 26," voltage detectors 27A to 27C are collectively referred to as "voltage detector 27," and battery ECUs 28A to 28C are collectively referred to as "battery ECU 28."

[0027] The battery stack 20 is a battery pack formed by connecting multiple single cells, for example, in series. The battery cells may be, for example, ternary lithium-ion batteries or lithium iron phosphate batteries. Alternatively, the battery cells may be nickel-metal hydride batteries. Battery pack B may be a battery pack repurposed from one installed in an electric vehicle. Battery pack B may include single cells instead of a battery pack.

[0028] Relay 22 is controlled by the battery ECU 28 to connect or disconnect the battery stack 20 and the DC / DC converter 1.

[0029] The current detector 24 detects the current flowing through the battery stack 20 and outputs a signal indicating the detected value. The current detector 26 is connected in series with the current detector 24, detects the current flowing through the battery stack 20, and outputs a signal indicating the detected value.

[0030] The detected current flowing through the battery stack 20 is used to calculate the power charged and discharged to the battery stack 20. To improve the reliability of the charge and discharge control of the battery stack 20, it is necessary to detect the current flowing through the battery stack 20 with high accuracy. Therefore, in this embodiment, the current detector for detecting the current flowing through the battery stack 20 is made into a redundant system of current detectors 24 and 26 to ensure the accuracy of detecting the current flowing through the battery stack 20. Current detector 24 corresponds to one embodiment of the "first current detector," and current detector 26 corresponds to one embodiment of the "second current detector."

[0031] The voltage detector 27 detects the voltage of the battery stack 20 and outputs a signal indicating the detected value. Although not shown in the diagram, the battery pack B is further equipped with a temperature detector for detecting the temperature of the battery stack 20.

[0032] The battery ECU 28 includes a processor and memory and monitors the corresponding battery stack 20. The battery ECU 28 transmits the output signals from the current detectors 24, 26, the voltage detector 27, and the temperature detector to the control device 30. The battery ECU 28 also calculates the State of Charge (SOC) of the battery stack 20 based on the output signals from the voltage detector 27 and the current detectors 24, 26, and transmits a signal indicating the calculated SOC to the control device 30. Furthermore, the battery ECU 28 controls the relay 22 according to the control signals provided by the control device 30.

[0033] Next, the operation of the battery system 100 according to this embodiment will be described. The battery system 100 according to this embodiment has a normal operation mode for charging and discharging between the battery system 100 and the external system 2, and an abnormality detection mode for detecting abnormalities in the current detectors 24 and 26.

[0034] In normal operation mode, the control device 30 controls multiple battery modules BM1 to BM3 in response to commands from the EMS 7. In this embodiment, the control device 30 performs droop control in each battery module BM. Specifically, the control device 30 controls the charging and discharging of the corresponding battery pack B in each of the multiple DC / DC converters 1A to 1C so that the boosted voltage, which is the voltage after boosting by the bidirectional chopper 10, becomes the target voltage. In a certain phase, the control device 30 calculates the voltage deviation between the target voltage and the detected value of the boosted voltage by the voltage detector 12, and determines the power to charge the corresponding battery pack B and the power to discharge from the corresponding battery pack B in proportion to the calculated voltage deviation.

[0035] In this way, in normal operation mode, droop control is performed in each of the DC / DC converters 1A to 1C, and the charging and discharging of the corresponding battery pack B is controlled so that the boosted voltage becomes the target voltage. In droop control, the control device 30 calculates the power to be charged and discharged to the corresponding battery pack B based on the output signals of the current detectors 24 and 26 and the voltage detector 27 provided by the battery ECU 28. The control device 30 then controls the charging and discharging of the corresponding battery pack B so that the calculated power does not exceed a power limit value set to suppress failure of the battery pack B.

[0036] In the above configuration, if both current detectors 24 and 26, which constitute the dual system, are functioning correctly, the detected value of current detector 24 and the detected value of current detector 26 will match. In this case, the control device 30 determines that the detected values ​​of current detectors 24 and 26 are the true values ​​of the current flowing through battery pack B, and uses these detected values ​​to calculate the power charged and discharged to battery pack B.

[0037] On the other hand, if either current detector 24 or 26 fails, the detected value from current detector 24 and the detected value from current detector 26 will no longer match. In this case, the control device 30 will determine that the detected value from either current detector 24 or 26 is not the true value of the current flowing through battery pack B. However, it will not be able to determine which of the current detectors 24 or 26 is failing.

[0038] The control device 30 determines that the reliability of the detected values ​​is low for battery pack B where the detected values ​​of the current detectors 24 and 26 do not match, and stops the operation of the corresponding DC / DC converter 1, thereby stopping the use of battery pack B itself. However, in this case, the use of battery pack B is restricted even if the other current detector 24 or 26 is functioning normally.

[0039] Therefore, in this embodiment, an abnormality detection mode is provided to detect abnormalities in the current detectors 24 and 26. In the abnormality detection mode, in battery pack B where the detected values ​​of current detectors 24 and 26 do not match, a normal current detector is selected from among the current detectors 24 and 26 using the method described below. In the normal operation mode after the abnormality detection mode, the charging and discharging of the battery pack B is controlled using the detected value of the selected normal current detector. This makes it possible to continue using the battery pack B using the detected value of the normal current detector.

[0040] During normal operation, the control device 30 determines whether a failure has occurred in the current detectors 24 and 26 of each battery module BM1 to BM3, based on the output signals of the current detectors 24 and 26 supplied from each battery pack B. Specifically, the control device 30 determines for each battery pack B whether the detected value of the current detector 24 matches the detected value of the current detector 26. If the detected values ​​of the current detectors 24 and 26 of all battery packs BA to BC in battery module BM match, the control device 30 determines that the current detectors 24 and 26 of that battery module BM are functioning normally. If the current detectors 24 and 26 of all battery modules BM1 to BM3 are functioning normally, the control device 30 continues to operate in normal operation mode.

[0041] On the other hand, if a battery pack B is detected in any of the battery modules BM1 to BM3 where the detected value of the current detector 24 and the detected value of the current detector 26 do not match, the control device 30 determines that either the current detector 24 or 26 of that battery pack B is faulty. In this case, the control device 30 stops the operation of the DC / DC converter 1 corresponding to the battery pack B that includes the faulty current detector. The control device 30 then transitions the battery system 100 from normal operation mode to abnormal detection mode.

[0042] EMS7 stops the operation of PCS3 in response to the battery system 100 transitioning to abnormal detection mode. In certain situations, the user (consumer) of the battery system 100 can, when the battery system 100 transitions to abnormal detection mode, perform an operation on EMS7 to select abnormal detection mode during a period when the battery system 100 is not charging or discharging with the external system 2. Upon receiving this operation, EMS7 stops the operation of PCS3, thereby stopping the exchange of power between the external system 2 and the battery system 100.

[0043] Next, the control device 30 stops the operation of the DC / DC converters 1A to 1C in other battery modules BM where the current detectors 24 and 26 are functioning normally. In abnormal detection mode, the control device 30 keeps all sub-relays SR1 to SR3 in the ON state. This is because, in an abnormal detection mode, if the sub-relay SR corresponding to the battery module BM where the current detectors 24 and 26 have failed is turned OFF, and then turned ON after the abnormal detection mode ends, there is a possibility that when the sub-relay SR is turned ON, an overcurrent will flow due to the difference in boosted voltage between battery modules BM1 to BM3, causing the sub-relay SR to weld together.

[0044] Figure 3 is a diagram illustrating the abnormality detection mode of the battery system 100. In Figure 3, a case is assumed in which current detectors 24A and 26A have failed in the battery pack BA of battery module BM1. Battery modules BM2 and BM3, in which current detectors 24 and 26 are functioning normally, are not shown.

[0045] As shown in Figure 3, if a failure occurs in the current detectors 24A and 26A in battery pack BA, the control device 30 operates the DC / DC converter 1A corresponding to battery pack BA and the DC / DC converter 1 corresponding to the other battery pack B.

[0046] For the other battery pack B, the battery pack B in which the current detectors 24 and 26 are functioning correctly is selected from among the multiple battery packs BA to BC. In the example in Figure 3, the control device 30 operates the DC / DC converter 1B corresponding to battery pack BB. The control device 30 also stops the operation of the DC / DC converter 1C corresponding to the remaining battery pack B (battery pack BC in Figure 3), excluding battery packs BA and BB.

[0047] The control device 30 operates DC / DC converters 1A and 1B to exchange power between battery pack BA and battery pack BB. In certain situations, as shown in Figure 3, the DC / DC converters 1A and 1B are operated to supply power from battery pack BA to battery pack BB. That is, battery pack BA is discharged and battery pack BB is charged.

[0048] Specifically, the control device 30 controls the bidirectional chopper 10A to output the power stored in the battery pack BA to the power line L, as shown by the thick solid line in Figure 3. While the bidirectional chopper 10A is being controlled, the current detectors 24A and 26A detect the current (discharge current) flowing through the battery stack 20A and output a signal indicating the detected value.

[0049] Furthermore, as shown by the thick solid line in Figure 3, the control device 30 controls the bidirectional chopper 10B to supply power from the battery pack BA via the bidirectional chopper 10A and power line L to the battery pack BB. While the bidirectional chopper 10B is being controlled, the current detectors 24B and 26B detect the current (charging current) flowing through the battery stack 20B and output a signal indicating the detected value.

[0050] When the control device 30 receives the output signals from current detectors 24A and 26A, and the output signals from current detectors 24B and 26B, it selects a normal current detector from current detectors 24A and 26A based on these output signals.

[0051] As shown in Figure 3, when power is supplied from battery stack 20A to battery stack 20B, the current flowing through battery stack 20A (discharge current) and the current flowing through battery stack 20B (charging current) have opposite directions of flow (polarity) and are equal in magnitude. Therefore, if current detectors 24A and 26A are functioning correctly, the detected values ​​from current detectors 24A and 26A and the detected values ​​from current detectors 24B and 26B should have opposite polarity and be equal in absolute value.

[0052] The control device 30 selects a normal current detector from among current detectors 24A and 26A by comparing the detected values ​​of current detectors 24A and 26A with the detected value of either current detector 24B or 26B. Specifically, if the detected value (absolute value) of current detector 24A matches the detected value (absolute value) of current detector 24B, but the detected value (absolute value) of current detector 26A does not match the detected value (absolute value) of current detector 24B, the control device 30 selects current detector 24A as the normal current detector and determines that current detector 26A is faulty.

[0053] Conversely, if the detected value (absolute value) of current detector 26A and the detected value (absolute value) of current detector 24B match, but the detected value (absolute value) of current detector 24A and the detected value (absolute value) of current detector 24B do not match, the control device 30 selects current detector 26A as a normal current detector and determines that current detector 24A is faulty.

[0054] In the normal operation mode after the abnormality detection mode has ended, the control device 30 controls the charging and discharging of the battery pack BA using the detected value of a normal current detector. This allows the battery pack BA to continue to be used using the detected value of a normal current detector.

[0055] Figure 4 is a flowchart illustrating the procedure for detecting abnormalities in the current detectors 24 and 26 by the control device 30. As shown in Figure 4, during operation of the battery system 100, the control device 30 determines in step S01 whether a failure has occurred in one of the current detectors 24 or 26 in any of the battery modules BM1 to BM3. In S01, the control device 30 determines in each battery module BM whether a failure has occurred in one of the current detectors 24 or 26 in each battery pack B, based on the output signals of the current detectors 24 and 26 supplied from the battery packs BA to BC.

[0056] If the detected values ​​of the current detectors 24 and 26 in each of the multiple battery modules BM1 to BM3 are the same, the control device 30 determines that the current detectors 24 and 26 are normal in all of the multiple battery modules BM1 to BM3 (NO determination in S01). In this case, the control device 30 executes the normal operation mode in step S12.

[0057] On the other hand, if the detected values ​​of the current detectors 24 and 26 of any of the battery packs BA to BC do not match in any of the battery modules BM1 to BM3, the control device 30 determines that a failure has occurred in one of the current detectors 24 and 26 of the battery pack B (YES determination in S01). In this case, in step S02, the control device 30 stops the operation of the DC / DC converter 1 corresponding to the battery pack B containing the failed current detector. Subsequently, in step S03, the control device 30 starts executing the abnormality detection mode.

[0058] In abnormality detection mode, the control device 30 first determines in step S04 whether or not the operation of PCS3 has been stopped. In S04, if the EMS7 has stopped the operation of PCS3 in response to an operation from the user (consumer) of the battery system 100, the determination is YES.

[0059] If the operation of PCS3 is stopped (when YES is determined in S04), the control device 30 proceeds to step S05 and stops the operation of multiple DC / DC converters 1A to 1C in the other battery module BM, which includes the normal current detectors 24 and 26.

[0060] Next, the control device 30 operates the DC / DC converter 1 corresponding to each of the two battery packs B so that power is exchanged between the battery pack B containing the faulty current detector (hereinafter also referred to as "the battery pack B to be detected") and the other battery pack B. In Figure 4, the control device 30 performs a discharge of the battery pack B to be detected in step S06. In S06, the control device 30 controls the bidirectional chopper 10 of the corresponding DC / DC converter 1 so that the power stored in the battery pack B to be detected is output to the power line L. While the bidirectional chopper 10 is being controlled, the current detectors 24 and 26 included in the battery pack B to be detected detect the current (discharge current) flowing through the battery stack 20 and output a signal indicating the detected value.

[0061] Furthermore, in step S07, the control device 30 performs charging of the other battery pack B. In S07, the control device 30 controls the bidirectional chopper 10 of the corresponding DC / DC converter 1 to supply power from the battery pack B being detected to the other battery pack B. While the bidirectional chopper 10 is being controlled, the current detectors 24 and 26 included in the other battery pack B detect the current (charging current) flowing through the battery stack 20 and output a signal indicating the detected value.

[0062] Furthermore, in step S08, the control device 30 stops charging and discharging the remaining battery packs B, excluding the battery pack B being detected and one other battery pack B. In S08, the control device 30 stops the operation of the DC / DC converter 1 corresponding to the remaining battery pack B.

[0063] Next, in step S09, the control device 30 acquires the output signals of the current detectors 24 and 26 from each of the battery pack B to be detected and the other battery pack B. Then, in step S10, the control device 30 selects a normal current detector from the current detectors 24 and 26 in the battery pack B to be detected based on the acquired output signals of the current detectors 24 and 26. In S10, the control device 30 selects a normal current detector by comparing the detected values ​​of the current detectors 24 and 26 of the battery pack B to the detected values ​​of the current detector 24 (or current detector 26) of the other battery pack B.

[0064] When a normal current detector is selected, the control device 30 terminates the abnormal detection mode in step S11. In the normal operation mode after the termination of the abnormal detection mode, the control device 30 controls the charging and discharging of the battery pack B to be detected using the detected value of the normal current detector.

[0065] In Figure 4, a configuration was described in which, during the abnormality detection process, the battery pack B to be detected is discharged (step S06), and the other battery pack B is charged (step S07). However, in this disclosure, it is sufficient to operate the DC / DC converter 1 corresponding to each battery pack B so that power is exchanged between the battery pack B to be detected and the other battery pack B. Therefore, as shown in the flowchart of Figure 5, a configuration in which the battery pack B to be detected is charged (step S06A), and the other battery pack B is discharged (step S07A) may also be used.

[0066] According to this embodiment, in a battery system configured to include multiple battery packs connected in parallel, the reliability of the detection values ​​of the current detectors, which are arranged in duplicate for each battery pack, can be increased. As a result, even if one of the duplicate current detectors fails, it is possible to continue using the corresponding battery pack using the detection value of the functioning current detector.

[0067] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0068] 1. 1A~1C Converter, 2. External System, 4. Power System, 5. Solar Power Generation Device, 6. Load, 7. EMS, 10. 10A~10C Bidirectional Chopper, 12. 12A~12C, 14. 14A~14C, 27. 27A~27C Voltage Detector, 16. 16A~16C MG-ECU, 20. 20A~20C Battery Stack, 22. 22A~22C Relay, 24. 24A~24C, 26. 26A~26C Current Detector, 28. 28A~28C Battery ECU, 30 Control Device, 100 Battery System, B. BA~BC Battery Pack, BM. BM1~BM3 Battery Module, SR. SR1~SR3 Sub-Relay.

Claims

1. A battery system that performs charging and discharging in and out of an external system, The external system comprises a plurality of battery packs connected to each other in parallel, Each of the aforementioned plurality of battery packs is provided with a plurality of DC / DC converters, each of which performs DC voltage conversion between the corresponding battery pack and the external system, The system includes a control device that controls the plurality of DC / DC converters, Each of the aforementioned plurality of battery packs is Battery stack and A first current detector for detecting the current flowing through the battery stack, It includes a second current detector connected in series with the first current detector for detecting the current flowing through the battery stack, If, in any one of the plurality of battery packs, the detected value of the first current detector and the detected value of the second current detector do not match, the control device shall The DC / DC converters corresponding to each of the aforementioned battery packs and the other battery pack are operated to exchange power between the aforementioned one battery pack and the other battery pack. A battery system that, during the operation of the DC / DC converter, selects a normal current detector from the first and second current detectors in one of the battery packs by comparing the detected values ​​of the first current detector in one of the battery packs with the detected value of the first current detector in the other battery pack.

2. If the detected value of the first current detector in any one of the aforementioned battery packs matches the detected value of the first current detector in any one of the aforementioned battery packs, the control device selects the first current detector in any one of the aforementioned battery packs as the normal current detector. The battery system according to claim 1, wherein if the detected value of the second current detector in any one of the aforementioned battery packs matches the detected value of the first current detector in the other one of the aforementioned battery packs, the control device selects the second current detector in any one of the aforementioned battery packs as the normal current detector.

3. The battery system according to claim 1 or 2, wherein, when the normal current detector is selected, the control device operates the DC / DC converter corresponding to any one of the battery packs using the detected value of the normal current detector.

4. The external system includes a power converter that performs bidirectional power conversion between the power grid and the battery system. If the detected value of the first current detector and the detected value of the second current detector do not match in any one of the plurality of battery packs, the power converter is stopped from operating. The battery system according to claim 1, wherein the control device operates the DC / DC converter corresponding to each of the one battery pack and the other battery pack while the power converter is stopped.

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