Battery system

Abstract

This process corrects the voltage detectors of multiple voltage detectors that detect the boosted voltages of multiple boost circuits connected in parallel. [Solution] The battery system 100 comprises a plurality of battery packs B connected in parallel to each other to an external system 2, and a plurality of DC / DC converters 1. Each DC / DC converter 1 includes a boost circuit 10 that boosts the DC voltage of the corresponding battery pack B and outputs the boosted voltage to the external system 2, and a voltage detector 12 that detects the boosted voltage. In correction mode, the control device 30 controls the boost circuit 10 of a first DC / DC converter 1 selected from the plurality of DC / DC converters 1, while stopping the operation of the boost circuits 10 of the remaining DC / DC converters 1. Based on the detected values ​​of the voltage detectors 12 of the plurality of DC / DC converters 1, the control device 30 corrects the voltage detector 12 of at least one of the plurality of DC / DC converters 1.

Description

Technical Field

[0001] The present disclosure relates to a battery system, and more particularly, to a technique for correcting a voltage detector disposed in a battery system configured to include a plurality of boost circuits.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2010-259265 (Patent Document 1) discloses an automobile including a first battery and a second battery connected in parallel to a drive circuit for driving an electric motor, and a first boost circuit and a second boost circuit provided corresponding to the first battery and the second battery, respectively, for boosting the voltage of the corresponding battery and supplying it to the drive circuit.

[0003] The above automobile further includes a first system main relay for connecting / disconnecting the first battery and the first boost circuit, a second system main relay for connecting / disconnecting the second battery and the second boost circuit, a voltage detector for detecting the voltage on the second battery side of the second boost circuit, and an abnormality determination means for determining an abnormality in the second boost circuit. The abnormality determination means determines that an abnormality has occurred in which the transistor constituting the upper arm of the second boost circuit is on-stuck when the detection value of the voltage detector is greater than or equal to a threshold value in a state where the first system main relay is turned on and the second system main relay is turned off.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In configurations with multiple boost circuits, such as the automobile described in Patent Document 1, it is common to provide a voltage detector for each boost circuit to detect the boosted voltage. Therefore, the entire battery system will have a configuration with multiple voltage detectors. If errors occur in the outputs of the multiple voltage detectors, there is a risk that the boosted voltage will not be able to be controlled accurately. For this reason, it is important to correct the multiple voltage detectors. However, Patent Document 1 does not mention anything about correcting the voltage detectors.

[0006] This disclosure was made to solve these problems, and the purpose of this disclosure is to correct the voltage detectors in a battery system comprising a plurality of battery packs connected in parallel and a plurality of voltage detectors that detect the boosted voltage of a plurality of boost circuits provided corresponding to each of the plurality of battery packs. [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 respect to 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 DC / DC converters includes a boost circuit that boosts the DC voltage of the corresponding battery pack and outputs the boosted voltage, which is the boosted voltage, to the external system, and a voltage detector for detecting the boosted voltage.

[0008] The battery system is configured to perform a normal operation mode for charging and discharging with an external system, and a correction mode for correcting the voltage detector. In the normal operation mode, the control unit controls the boost circuit for each of the multiple DC / DC converters using the detected value of the voltage detector. In the correction mode, the control unit controls the boost circuit of a first DC / DC converter selected from the multiple DC / DC converters, while shutting down the operation of the boost circuits of the remaining DC / DC converters. While controlling the boost circuit of the first DC / DC converter, the control unit corrects the voltage detector of at least one of the multiple DC / DC converters based on the detected values ​​of the voltage detectors of the multiple DC / DC converters.

[0009] This configuration allows for the correction of multiple voltage detectors that detect the boosted voltages of multiple boost circuits. The correction of the voltage detectors reduces their detection errors, thereby suppressing errors in the power charged and discharged to the corresponding battery packs. This eliminates the need for larger wiring in the battery system's wiring design.

[0010] Preferably, while controlling the boost circuit of the first DC / DC converter, the control device estimates the true value of the boosted voltage in the boost circuit of the first DC / DC converter based on the detected values ​​of the voltage detectors of the multiple DC / DC converters. The control device corrects the voltage detector of at least one DC / DC converter using the estimated true value.

[0011] In this configuration, the detection error of the voltage detector is determined from the difference between the estimated true value and the detected value of the voltage detector. Then, a correction value for the voltage detector is calculated based on the determined detection error, so that the detected value of the voltage detector can be corrected according to the correction value.

[0012] Preferably, the external system includes a power converter that performs bidirectional power conversion between the power grid and the battery system. The control device performs a correction mode when the power converter is shut down.

[0013] This configuration allows for voltage detector correction during periods when the battery system is not charging or discharging with an external system.

[0014] Preferably, in normal operation mode, the control device performs droop control of the boost circuit in each of the multiple DC / DC converters based on the detected value of the voltage detector.

[0015] This configuration reduces the detection error of the voltage detector, thereby suppressing errors in the power charged and discharged to the corresponding battery pack during droop control. [Effects of the Invention]

[0016] According to this disclosure, in a battery system comprising multiple battery packs connected in parallel and multiple voltage detectors that detect the boosted voltage of multiple boost circuits provided corresponding to each of the multiple battery packs, the multiple voltage detectors can be corrected. [Brief explanation of the drawing]

[0017] [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 correction modes of the battery system. [Figure 4] This is a flowchart illustrating the procedure for correcting the voltage detector using a control device. [Modes for carrying out the invention]

[0018] 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.

[0019] FIG. 1 is a schematic configuration diagram of a battery system according to the present embodiment. As shown in FIG. 1, a battery system 100 according to the present embodiment is connected to an external system 2 via a power line L. The battery system 100 can supply power to the external system 2 and can discharge to the external system 2. The battery system 100 is applied, for example, to a stationary power storage system installed in a consumer's home.

[0020] The battery system 100 includes a plurality of battery modules BM1 to BM3, a plurality of sub-relays SR1 to SR3, and a control device 30. Hereinafter, the battery modules BM1 to BM3 are also collectively referred to as "battery modules BM", and the sub-relays SR1 to SR3 are also collectively referred to as "sub-relays SR". In the example of FIG. 1, the battery system 100 includes three battery modules BM and three sub-relays SR, but the number of each of the battery modules BM and the sub-relays SR is arbitrary and may be a single number.

[0021] The plurality of battery modules BM1 to BM3 are connected in parallel to each other with respect to the external system 2. The plurality of sub-relays SR1 to SR3 are provided corresponding to the plurality of battery modules BM1 to BM3, respectively. The sub-relay SR is controlled by the control device 30 and connects or disconnects the corresponding battery module BM and the external system 2. In a certain aspect, 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. When a failure occurs in the corresponding battery module BM during the operation of the battery system 100, the sub-relay SR is turned off and the corresponding battery module BM is disconnected from the external system 2.

[0022] The battery module BM1 includes a plurality of battery packs BA to BC and a plurality of DC / DC converters 1A to 1C. Hereinafter, the battery packs BA to BC are also collectively referred to as "battery pack B", and the DC / DC converters 1A to 1C are also collectively referred to as "DC / DC converter 1". In the example of FIG. 1, the battery module BM1 includes three battery packs B and three DC / DC converters 1, but the number of each of the battery pack B and the DC / DC converter 1 may be plural.

[0023] The plurality of battery packs BA to BC are connected in parallel to each other with respect to the external system 2 via the sub-relay SR1. The battery pack B includes a battery stack.

[0024] The plurality of DC / DC converters 1A to 1C are provided corresponding to the plurality of battery packs BA to BC respectively. The DC / DC converter 1 controls the charge and discharge of the corresponding battery pack B by performing DC voltage conversion between the corresponding battery pack B and the external system 2. Specifically, the DC / DC converter 1 includes a boost circuit and a buck circuit. The boost circuit boosts the DC voltage of the corresponding battery pack B and outputs the boosted voltage, which is the boosted voltage, to the external system 2 to control the discharge of the corresponding battery pack B. The buck circuit buck-boosts the DC voltage from the external system 2 and outputs the buck-boosted voltage, which is the buck-boosted voltage, to the corresponding battery pack B to control the charging of the corresponding battery pack B. The boost circuit and the buck circuit are realized by, for example, a bidirectional chopper.

[0025] Although illustration is omitted, the configuration of each of the battery modules BM2 and BM3 is the same as the configuration of the battery module BM1.

[0026] External system 2 comprises a Power Conditioning System (PCS) 3, a power grid (PG) 4, a photovoltaic (PV) system 5, a load 6, and an Energy Management System (EMS) 7. PCS 3 includes a power converter capable of both AC / DC and DC / AC conversion. PCS 3 converts DC power from, for example, the photovoltaic system 5 or battery system 100 into AC power and supplies it to the load 6. The load 6 is an electrical appliance installed at the customer's premises, such as an air conditioner and lighting fixtures. PCS 3 exchanges AC power with the power grid 4. The power grid 4 is not limited to a large-scale power network established as infrastructure, but may also be a microgrid.

[0027] EMS7 works in conjunction with PCS3 to manage energy usage at the consumer. EMS7 includes HEMS (Home EMS), BEMS (Building EMS), and FEMS (Factory EMS), among others. EMS7 includes a processor and memory.

[0028] The control device 30 includes a processor and memory, and controls the battery system 100 upon receiving commands from the EMS 7. Specifically, the control device 30 controls multiple sub-relays SR1 to SR3, as well as multiple DC / DC converters 1A to 1C in each battery module BM.

[0029] 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".

[0030] 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 via the power line L. The bidirectional chopper 10 corresponds to one embodiment of a "boost circuit". 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.

[0031] 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.

[0032] 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.

[0033] Battery pack BA includes a battery stack 20A, a relay 22A, a voltage detector 24A, and a battery ECU 26A. Battery pack BB includes a battery stack 20B, a relay 22B, a voltage detector 24B, and a battery ECU 26B. Battery pack BC includes a battery stack 20C, a relay 22C, a voltage detector 24C, and a battery ECU 26C. 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." Voltage detectors 24A to 24C will also be collectively referred to as "voltage detector 24," and battery ECUs 26A to 26C will also be collectively referred to as "battery ECU 26."

[0034] 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.

[0035] Relay 22 is controlled by the battery ECU 26 to connect or disconnect the battery stack 20 and the DC / DC converter 1.

[0036] The voltage detector 24 detects the voltage of the battery stack 20 and outputs a signal indicating the detected value. Although not shown in the diagram, in addition to the voltage detector 24, the battery pack B is further equipped with a current detector for detecting the current flowing through the battery stack 20 and a temperature detector for detecting the temperature of the battery stack 20.

[0037] The battery ECU 26 includes a processor and memory and monitors the corresponding battery stack 20. The battery ECU 26 transmits the output signals from the voltage detector 24, current detector, and temperature detector to the control device 30. The battery ECU 26 also calculates the State of Charge (SOC) of the battery stack 20 based on the output signals from the voltage detector 24 and current detector, and transmits a signal indicating the calculated SOC to the control device 30. Furthermore, the battery ECU 26 controls the relay 22 according to the control signals provided by the control device 30.

[0038] 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 with an external system 2, and a correction mode for correcting voltage detectors 12A to 12C.

[0039] In normal operation mode, the control device 30 receives commands from the EMS 7 and controls multiple battery modules BM1 to BM3. 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.

[0040] In certain situations, the control device 30 calculates the voltage difference between the target voltage and the boosted voltage detected by the voltage detector 12 in each DC / DC converter 1. Then, the control device 30 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 difference.

[0041] Furthermore, if any of the battery packs BA to BC in the battery module BM1 fail during normal operation, the control device 30 disconnects the battery module BM1 from the external system 2 by turning off the sub-relay SR1.

[0042] Thus, 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. However, the boosted voltages of DC / DC converters 1A to 1C do not always match due to differences in the current flowing through battery packs BA to BC, and control variations in bidirectional choppers 10A to 10C. Therefore, in normal operation mode, even if the detected values ​​of voltage detectors 12A to 12C are compared, it is not possible to correct the voltage detectors 12A to 12C.

[0043] Therefore, in this embodiment, a correction mode is provided for correcting the voltage detectors 12A to 12C. Then, depending on the energy usage situation of the consumer, either the normal operation mode or the correction mode is selected. In certain situations, the user (consumer) of the battery system 100 can select either the normal operation mode or the correction mode. In this case, the user can perform an operation on the EMS 7 to select the correction mode during a time when the battery system 100 is not charging or discharging with the external system 2. When the EMS 7 receives this operation, it stops the operation of the PCS 3, thereby stopping the charging and discharging of the battery system 100.

[0044] While PCS3 is shut down, the control device 30 executes a correction mode. In correction mode, the control device 30 selects one battery module BM from the multiple battery modules BM1 to BM3 as the target for correction. For the battery module BM that was not selected as the target for correction, the control device 30 stops the operation of the DC / DC converters 1A to 1C.

[0045] Furthermore, during correction mode, the control device 30 maintains all sub-relays SR1 to SR3 in the ON state. This is because, in a configuration where the sub-relay SR corresponding to the battery module BM to be corrected is turned OFF during correction mode and then turned ON after the correction mode ends, there is a risk that when the sub-relay SR is turned ON, an overcurrent will flow due to the difference in boosted voltage between the battery modules BM1 to BM3, causing the sub-relay SR to weld together.

[0046] Figure 3 is a diagram illustrating the correction mode of the battery system 100. In Figure 3, battery module BM1 is selected as the target for correction. Battery modules BM2 and BM3, which were not selected as the target for correction, are omitted from the illustration.

[0047] As shown in Figure 3, in correction mode, the control device 30 selects one DC / DC converter 1 from among the multiple DC / DC converters 1A to 1C included in the battery module BM1 to be corrected. In the example in Figure 3, the control device 30 selects DC / DC converter 1A. The selected DC / DC converter 1A corresponds to the "first DC / DC converter".

[0048] Next, the control device 30 controls the bidirectional chopper 10A of the selected DC / DC converter 1A. Meanwhile, the control device 30 stops the operation of the bidirectional choppers 10B and 10C of the remaining DC / DC converters 1B and 1C that were not selected.

[0049] The bidirectional chopper 10A is controlled by the control device 30, which boosts the DC voltage of the battery pack BA and outputs the boosted voltage to the power line L. The voltage detector 12A detects the boosted voltage of the bidirectional chopper 10A and outputs a signal indicating the detected value.

[0050] As shown by the thick solid line in Figure 3, the boosted voltage from the bidirectional chopper 10A is applied to the capacitor C1 of the bidirectional chopper 10B via the power line L. The voltage detector 12B detects the voltage across the terminals of capacitor C1 and outputs a signal indicating the detected value. In other words, the voltage detector 12B detects the boosted voltage from the bidirectional chopper 10A.

[0051] Similarly, the boosted voltage from the bidirectional chopper 10A is applied to the capacitor C1 of the bidirectional chopper 10C via the power line L. The voltage detector 12C detects the voltage across the terminals of capacitor C1 and outputs a signal indicating the detected value. In other words, the voltage detector 12C detects the boosted voltage from the bidirectional chopper 10A.

[0052] If all voltage detectors 12A to 12C are functioning correctly, the detected values ​​of voltage detector 12A, voltage detector 12B, and voltage detector 12C will match. Conversely, if at least one of the voltage detectors 12A to 12C is faulty, the detected values ​​of voltage detector 12A, voltage detector 12B, and voltage detector 12C will not match. For example, if one of the voltage detectors 12A to 12C is faulty and the other two are functioning correctly, two of the three detected values ​​will match, while the remaining value will not match these two.

[0053] When the control device 30 receives the output signals from the voltage detectors 12A to 12C, it corrects the voltage detector 12 using the detected values ​​from the voltage detectors 12A to 12C. Specifically, the control device 30 first estimates the true value of the boosted voltage at the bidirectional chopper 10A of the DC / DC converter 1 (the first DC / DC converter) by comparing the detected values ​​from the voltage detectors 12A to 12C. For example, the control device 30 estimates the true value of the boosted voltage at the bidirectional chopper 10A by majority vote of the detected values ​​from the voltage detectors 12A to 12C. As described above, if one of the voltage detectors 12A to 12C is faulty and the remaining two voltage detectors 12 are normal, two of the three detected values ​​will match, and the remaining detected value will not match these two. In this case, the control device 30 estimates that the two matching detected values ​​are the true value of the boosted voltage at the bidirectional chopper 10A.

[0054] Next, the control device 30 corrects at least one voltage detector 12 using the estimated true value of the boosted voltage. In the case described above, the control device 30 corrects the voltage detector 12 that output the remaining detected value. Specifically, the control device 30 takes the difference between the remaining detected value and the estimated true value of the boosted voltage as the detection error of the voltage detector 12, and calculates a correction value for the voltage detector 12 based on this detection error. After the correction mode ends, the boosted voltage of the corresponding bidirectional chopper 10 is detected by correcting the detected value of the voltage detector 12 according to the above correction value.

[0055] Furthermore, the method for estimating the true value of the boosted voltage in the bidirectional chopper 10 is not limited to majority voting; known statistical methods can be used. For example, the true value of the boosted voltage in the bidirectional chopper 10 can be estimated from the average value and standard deviation of the detected values ​​of multiple voltage detectors 12.

[0056] Figure 4 is a flowchart illustrating the procedure for correcting the voltage detector 12 by the control device 30. As described above, the correction process for the voltage detector 12 is performed while the PCS3 is shut down.

[0057] As shown in Figure 4, in step S01, the control device 30 selects one battery module BM to be corrected from among the multiple battery modules BM1 to BM3 included in the battery system 100. In step S02, the control device 30 further stops the operation of multiple DC / DC converters 1A to 1C in the battery module BM that was not selected for correction. In correction mode, the control device 30 keeps all sub-relays SR1 to SR3 in the ON state.

[0058] In step S03, the control device 30 selects one DC / DC converter 1 (the first DC / DC converter) from among multiple DC / DC converters 1A to 1C in the battery module BM to be corrected.

[0059] Next, in step S04, the control device 30 controls the bidirectional chopper 10 of the selected DC / DC converter 1. The bidirectional chopper 10, controlled by the control device 30, boosts the DC voltage of the corresponding battery pack B and outputs the boosted voltage to the power line L. The voltage detector 12 detects the boosted voltage of the bidirectional chopper 10 and outputs a signal indicating the detected value.

[0060] In step S05, the control device 30 stops the operation of the bidirectional choppers 10 of the remaining DC / DC converters 1 that were not selected in the battery module BM to be corrected. In each of the remaining DC / DC converters 1, the voltage detector 12 detects the voltage applied to the capacitor C1 of the bidirectional chopper 10 via the power line L and outputs a signal indicating the detected value. That is, the voltage detector 12 detects the boosted voltage of the bidirectional chopper 10 of the first DC / DC converter 1.

[0061] In step S06, the control device 30 acquires signals indicating the detected boost voltage of the bidirectional chopper 10 from multiple voltage detectors 12A to 12C, each corresponding to one of the multiple DC / DC converters 1A to 1C.

[0062] In step S07, the control device 30 corrects at least one of the voltage detectors 12A to 12C based on the detected values ​​of the multiple voltage detectors 12A to 12C. In S07, the control device 30 estimates the true value of the boosted voltage in the bidirectional chopper 10 of the DC / DC converter 1 (first DC / DC converter) by comparing the detected values ​​of the multiple voltage detectors 12A to 12C. Then, the control device 30 corrects at least one voltage detector 12 using the estimated true value of the boosted voltage.

[0063] As described above, according to this embodiment, the voltage detector 12 located in a battery system 100 which is configured to include a plurality of parallel-connected boost circuits (bidirectional choppers 10) can be corrected.

[0064] In the droop control of the DC / DC converter 1, the boosted voltage of the bidirectional chopper 10 (boost circuit) is detected by the voltage detector 12, and the power charged and discharged to the corresponding battery pack B is controlled so that the detected value of the voltage detector 12 becomes the target voltage. In droop control, the detection error of the voltage detector 12 leads to an error in the power charged and discharged to the battery pack B. Therefore, the battery system 100 requires wiring design that takes this power error into account. Because the wiring, such as power lines L, is designed to account for the increase in power due to the detection error of the voltage detector 12, there is a concern that the wiring will become larger.

[0065] According to this disclosure, the detection error of the voltage detector 12 is reduced by the correction of the voltage detector 12, thereby suppressing errors in the power charged and discharged to the battery pack B. As a result, it becomes unnecessary to increase the size of the wiring in the wiring design of the battery system 100.

[0066] 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]

[0067] 1. 1A~1C DC / DC converter, 2. External system, 4. Power grid, 5. Solar power generation device, 6. Load, 7. EMS, 10. 10A~10C bidirectional chopper, 12. 12A~12C, 14. 14A~14C voltage detector, 16. 16A~16C MG-ECU, 20. 20A~20C battery stack, 22. 22A~22C relay, 26. 26A~26C battery ECU, 30 control device, 100 battery system, B, BA~BC battery pack, BM, BM1~BM3 battery module, L power line, 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 DC / DC converters is A boost circuit that boosts the DC voltage of the corresponding battery pack and outputs the boosted voltage, which is the boosted voltage, to the external system, It includes a voltage detector for detecting the boosted voltage, The battery system is configured to perform a normal operation mode for charging and discharging with the external system, and a correction mode for correcting the voltage detector. In the normal operation mode, the control device controls the boost circuit for each of the plurality of DC / DC converters using the detected value of the voltage detector. In the correction mode, the control device While controlling the boost circuit of the first DC / DC converter selected from the plurality of DC / DC converters, the operation of the boost circuits of the remaining DC / DC converters is stopped. A battery system that, while controlling the boost circuit of the first DC / DC converter, corrects the voltage detector of at least one of the plurality of DC / DC converters based on the detected value of the voltage detector of the plurality of DC / DC converters.

2. During the control of the boost circuit of the first DC / DC converter, the control device, Based on the detected values ​​of the voltage detectors of the plurality of DC / DC converters, the true value of the boosted voltage in the boost circuit of the first DC / DC converter is estimated. The battery system according to claim 1, wherein the voltage detector of the at least one DC / DC converter is corrected using the estimated true value.

3. The external system includes a power converter that performs bidirectional power conversion between the power grid and the battery system. The battery system according to claim 1, wherein the control device executes the correction mode while the power converter is stopped.

4. The battery system according to any one of claims 1 to 3, wherein in the normal operating mode, the control device performs droop control of the boost circuit in each of the plurality of DC / DC converters based on the detected value of the voltage detector.

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