Battery system

Abstract

The voltage detector correction of a plurality of voltage detectors that detect the boosted voltages of a plurality of boosted circuits connected in parallel is performed. A battery system (100) is provided with a plurality of battery packs (B) connected in parallel to an external system (2), and a plurality of DC / DC converters (1). Each DC / DC converter (1) includes: a booster circuit (10) that boosts the DC voltage of the corresponding battery pack (B) and outputs the boosted voltage to an external system (2); and a voltage detector (12) that detects the boosted voltage. In the 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), and stops the operation of the boost circuits (10) of the remaining 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) on the basis of the detection values of the voltage detectors (12) of the plurality of DC / DC converters (1).

Description

Battery System Technical Field

[0001] This disclosure relates to battery systems, and more particularly, to techniques for calibrating voltage detectors configured in a battery system comprising multiple boost circuits. Background Technology

[0002] Japanese Patent Application Publication No. 2010-259265 (Patent Document 1) discloses an automobile comprising: a first battery and a second battery connected in parallel with a drive circuit that drives an electric motor; a first boost circuit and a second boost circuit respectively provided with the first battery and the second battery, which boost the voltage of the corresponding battery and supply it to the drive circuit.

[0003] The aforementioned vehicle also includes: a first system main relay for connecting / disconnecting the first battery from the first boost circuit; a second system main relay for connecting / disconnecting the second battery from the second boost circuit; a voltage detector for detecting the voltage on the second battery side of the second boost circuit; and an anomaly determination unit for determining an anomaly in the second boost circuit. When the voltage detector's value is equal to or greater than a threshold while the first system main relay is on and the second system main relay is off, the anomaly determination unit determines that an anomaly has occurred where the transistor constituting the upper arm of the second boost circuit is fixed to be on.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-259265 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] As described in Patent Document 1, in a structure with multiple boost circuits, each boost circuit typically has a voltage detector for detecting the boosted voltage. Therefore, this results in a structure with multiple voltage detectors configured within the overall battery system. If the outputs of these multiple voltage detectors produce errors, the boosted voltage may not be accurately controlled. Therefore, calibrating these multiple voltage detectors becomes important. However, Patent Document 1 makes no mention whatsoever of voltage detector calibration.

[0008] This disclosure was made to solve such a problem. The purpose of this disclosure is to calibrate multiple voltage detectors in a battery system having multiple battery packs connected in parallel and multiple voltage detectors that detect the boost voltage of multiple boost circuits respectively provided for the multiple battery packs.

[0009] Methods for solving problems

[0010] According to one aspect of this disclosure, a battery system for charging and discharging with an external system includes: multiple battery packs connected in parallel to the external system; multiple DC / DC converters; and a control device for controlling the multiple DC / DC converters. The multiple DC / DC converters are configured corresponding to the multiple battery packs and perform DC-DC voltage conversion between their respective battery packs and the external system. Each of the multiple DC / DC converters includes: a boost circuit for boosting the DC voltage of the corresponding battery pack and outputting the boosted voltage, i.e., the boosted voltage, to the external system; and a voltage detector for detecting the boosted voltage.

[0011] The battery system is configured to perform a normal operating mode for charging and discharging with an external system and a calibration mode for calibrating voltage detectors. In the normal operating mode, the control device uses the detection value of the voltage detector for each of the plurality of DC / DC converters to control the boost circuit. In the calibration mode, the control device controls the boost circuit of a first DC / DC converter selected from the plurality of DC / DC converters, while stopping the operation of the boost circuits of the remaining DC / DC converters. In controlling the boost circuit of the first DC / DC converter, the control device calibrates the voltage detector of at least one of the plurality of DC / DC converters based on the detection value of the voltage detector of the plurality of DC / DC converters.

[0012] This structure allows for the calibration of multiple voltage detectors that individually detect the boost voltage of multiple boost circuits. By reducing the detection error of the voltage detectors through calibration, errors in the charging and discharging power within the corresponding battery pack are suppressed. Consequently, large-scale wiring is eliminated in the battery system wiring design.

[0013] Preferably, in the control of the boost circuit of the first DC / DC converter, the control device estimates the true value of the boost voltage in the boost circuit of the first DC / DC converter based on the detection values ​​of the voltage detectors of multiple DC / DC converters. The control device uses the estimated true value to calibrate the voltage detector of at least one DC / DC converter.

[0014] Based on this structure, the detection error of the voltage detector is calculated by the difference between the estimated true value and the detected value of the voltage detector. Furthermore, a correction value for the voltage detector is calculated based on the calculated detection error, thus enabling the voltage detector's detected value to be corrected according to the correction value.

[0015] Preferably, the external system includes a power conversion device that performs bidirectional power conversion between the power system and the battery system. The control device executes a correction mode when the power conversion device stops operating.

[0016] According to this structure, the voltage detector can be calibrated during the time period when the battery system and the external system are not charging or discharging.

[0017] Preferably, in normal operating mode, the control device performs droop control of the boost circuit in each of the multiple DC / DC converters based on the detection value of the voltage detector.

[0018] According to this structure, since the detection error of the voltage detector is reduced, the error in the power supplied to the corresponding battery pack during droop control can be suppressed.

[0019] The effects of the invention

[0020] According to this disclosure, in a battery system having multiple battery packs connected in parallel and multiple voltage detectors that detect the boost voltage of multiple boost circuits respectively provided corresponding to the multiple battery packs, it is possible to calibrate the multiple voltage detectors. Attached Figure Description

[0021] Figure 1 is a schematic configuration diagram of a battery system according to an embodiment of the present disclosure.

[0022] Figure 2 is a diagram showing the structure of the battery module.

[0023] Figure 3 is a diagram illustrating the calibration modes of the battery system.

[0024] Figure 4 is a flowchart illustrating the steps of the voltage detector calibration process performed by the control device. Detailed Implementation

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0026] Figure 1 is a schematic configuration diagram of the battery system according to this embodiment. As shown in Figure 1, the battery system 100 of this embodiment is connected to an external system 2 via a power line L. The battery system 100 is capable of receiving power from the external system 2 and discharging into the external system 2. The battery system 100 is, for example, applied to a stationary energy storage system installed at a customer's premises.

[0027] The battery system 100 includes multiple battery modules BM1 to BM3, multiple auxiliary relays SR1 to SR3, and a control device 30. Hereinafter, battery modules BM1 to BM3 will be collectively referred to as "battery module BM," and auxiliary relays SR1 to SR3 will be collectively referred to as "auxiliary relays SR." In the example of Figure 1, the battery system 100 has 3 battery modules BM and 3 auxiliary relays SR, but the number of each battery module BM and auxiliary relay SR is arbitrary and can be a single unit.

[0028] Multiple battery modules BM1 to BM3 are connected in parallel with respect to the external system 2. Multiple auxiliary relays SR1 to SR3 are respectively configured to correspond to the multiple battery modules BM1 to BM3. The auxiliary 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 aspect, when the battery system 100 is started, the auxiliary relay SR is activated, and the corresponding battery module BM is connected to the external system 2. If a fault occurs in the corresponding battery module BM during the operation of the battery system 100, the auxiliary relay SR is deactivated, and the corresponding battery module BM is disconnected from the external system 2.

[0029] Battery module BM1 comprises multiple battery packs BA~BC and multiple DC / DC converters 1A~1C. Hereinafter, battery packs BA~BC will be collectively referred to as "Battery Pack B," and DC / DC converters 1A~1C will be collectively referred to as "DC / DC Converter 1." In the example of Figure 1, battery module BM1 comprises 3 battery packs B and 3 DC / DC converters 1, but the number of each battery pack B and DC / DC converter 1 can be multiple.

[0030] Multiple battery packs BA~BC are connected in parallel with respect to external system 2 via auxiliary relay SR1. Battery pack B contains a battery stack.

[0031] Multiple DC / DC converters 1A~1C are respectively configured to correspond to multiple battery packs BA~BC. DC / DC converter 1 controls the charging and discharging of the corresponding battery pack B by performing DC-DC voltage conversion between the corresponding battery pack B and the external system 2. Specifically, 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 to the external system 2, thereby controlling the discharging of the corresponding battery pack B. The buck circuit bucks the DC voltage from the external system 2 and outputs the buck voltage to the corresponding battery pack B, thereby controlling the charging of the corresponding battery pack B. The boost and buck circuits are implemented, for example, using a bidirectional chopper.

[0032] Although the illustrations are omitted, the structures of battery modules BM2 and BM3 are the same as those of battery module BM1.

[0033] External system 2 comprises a PCS (Power Conditioning System) 3, a power system (PG) 4, a solar power generation device (PV) 5, a load 6, and an EMS (Energy Management System) 7. PCS 3 includes power conversion devices capable of both AC / DC and DC / AC conversion. For example, PCS 3 converts DC power from solar power generation device 5 or battery system 100 into AC power and supplies it to load 6. Load 6 includes, for example, electrical products installed at the customer's premises such as air conditioners and lighting fixtures. PCS 3 transmits and receives AC power from and from power system 4. Power system 4 is not limited to a large-scale power grid as infrastructure, but can also be a microgrid.

[0034] EMS 7 works in conjunction with PCS 3 to manage customer energy usage. EMS 7 includes HEMS (Home EMS), BEMS (Building EMS), FEMS (Factory EMS), etc. EMS 7 includes a processor and memory.

[0035] The control device 30 includes a processor and a memory, receives instructions from the EMS 7, and controls the battery system 100. Specifically, the control device 30 controls multiple auxiliary relays SR1 to SR3 and multiple DC / DC converters 1A to 1C in each battery module BM.

[0036] Figure 2 is a diagram showing the structure of battery module BM. Figure 2 representatively illustrates the structure of battery module BM1. As shown in Figure 2, DC / DC converter 1A includes a bidirectional chopper 10A, voltage detectors 12A and 14A, and an MG-ECU (MotorGenerator-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. Hereinafter, 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".

[0037] The bidirectional chopper 10 is a known chopper that includes multiple semiconductor switching elements. In the example of 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, i.e., the boost voltage, to the external system 2 via the power line L. The bidirectional chopper 10 corresponds to one embodiment of a "boost circuit". In addition, the bidirectional chopper 10 steps down the DC voltage from the external system 2 and outputs the stepped-down voltage, i.e., the stepped-down voltage, to the corresponding battery pack B.

[0038] Voltage detector 14 detects the voltage before boosting (DC voltage of battery pack B) of bidirectional chopper 10 and outputs a signal representing the detected value. Voltage detector 12 detects the voltage after boosting (i.e., boost voltage) of bidirectional chopper 10 and outputs a signal representing the detected value.

[0039] The MG-ECU 16 is a device for controlling the communication between the bidirectional chopper 10 and the control device 30, and includes a processor and a memory. The MG-ECU 16 sends the output signals of the voltage detectors 12 and 14 to the control device 30. Additionally, the MG-ECU 16 receives control signals from the control device 30 for controlling the bidirectional chopper 10. The bidirectional chopper 10 performs DC-DC voltage conversion according to the control signals from the control device 30.

[0040] Battery pack BA includes battery stack 20A, relay 22A, voltage detector 24A, and battery ECU 26A. Battery pack BB includes battery stack 20B, relay 22B, voltage detector 24B, and battery ECU 26B. Battery pack BC includes battery stack 20C, relay 22C, voltage detector 24C, and battery ECU 26C. Hereinafter, battery stacks 20A-20C will be collectively referred to as "Battery Stack 20," and relays 22A-22C will be collectively referred to as "Relay 22." Voltage detectors 24A-24C will also be collectively referred to as "Voltage Detector 24," and battery ECUs 26A-26C will also be collectively referred to as "Battery ECU 26."

[0041] Battery stack 20 is a battery pack formed by connecting multiple individual cells (battery units) in series, for example. The battery unit can be, for example, a ternary lithium-ion battery or a lithium-ion iron phosphate battery. Alternatively, the battery unit can be a nickel-metal hydride battery. Battery pack B can also be a battery pack that utilizes a battery pack used in electric vehicles. Battery pack B can also contain individual cells instead of a battery pack.

[0042] Relay 22 is controlled by battery ECU 26 to connect or disconnect battery stack 20 from DC / DC converter 1.

[0043] Voltage detector 24 detects the voltage of battery stack 20 and outputs a signal representing the detected value. Although not shown, in addition to voltage detector 24, battery pack B also includes a current detector for detecting the current flowing through battery stack 20 and a temperature detector for detecting the temperature of battery stack 20.

[0044] The battery ECU 26 includes a processor and memory, and monitors the corresponding battery stack 20. The battery ECU 26 sends the output signals of the voltage detector 24, current detector, and temperature detector to the control device 30. Furthermore, the battery ECU 26 calculates the State of Charge (SOC) of the battery stack 20 based on the output signals of the voltage detector 24 and current detector, and sends a signal representing the calculated SOC to the control device 30. Additionally, the battery ECU 26 controls the relay 22 according to the control signals provided from the control device 30.

[0045] 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 the external system 2 and a calibration mode for calibrating the voltage detectors 12A to 12C.

[0046] In normal operating mode, the control device 30 receives instructions 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 of the bidirectional chopper 10 becomes the target voltage.

[0047] In one respect, the control device 30 calculates the voltage deviation between the target voltage and the detected value of the boost voltage detected by the voltage detector 12 in each DC / DC converter 1. Then, the control device 30 determines the amount of power to charge the corresponding battery pack B and the amount of power to discharge the corresponding battery pack B in proportion to the calculated voltage deviation.

[0048] Furthermore, during normal operation, if any one of the multiple battery packs BA~BC in the battery module BM1 fails, the control device 30 disconnects the battery module BM1 from the external system 2 by disconnecting the auxiliary relay SR1.

[0049] Thus, in normal operation, droop control is performed in each DC / DC converter 1A~1C to control the charging and discharging of the corresponding battery pack B, so that the boost voltage becomes the target voltage. However, the boost voltage of DC / DC converters 1A~1C may not be consistent due to differences in the current flowing in battery packs BA~BC and control fluctuations in bidirectional choppers 10A~10C. Therefore, in normal operation, even if the detection values ​​of voltage detectors 12A~12C are compared, voltage detectors 12A~12C cannot be calibrated.

[0050] Therefore, in this embodiment, a calibration mode is provided for calibrating the voltage detectors 12A to 12C. Furthermore, depending on the customer's energy usage, either a normal operating mode or a calibration mode is selected. In one aspect, the user (customer) of the battery system 100 can select either a normal operating mode or a calibration mode. In this case, the user can perform the operation of selecting the calibration mode on the EMS 7 during periods when the battery system 100 is not being charged or discharged with the external system 2. If the EMS 7 accepts this operation, it stops the charging and discharging of the battery system 100 by stopping the operation of the PCS 3.

[0051] When PCS 3 stops operating, control device 30 executes calibration mode. In calibration mode, control device 30 selects one battery module BM from multiple battery modules BM1 to BM3 as the calibration target. Control device 30 stops the operation of DC / DC converters 1A to 1C in the battery module BM that was not selected as the calibration target.

[0052] Furthermore, in calibration mode, the control device 30 keeps all auxiliary relays SR1 to SR3 in the ON state. This is because, in calibration mode, in a configuration where the auxiliary relay SR corresponding to the battery module BM to be calibrated is disconnected and then turned on after the calibration mode ends, the difference in boost voltage between battery modules BM1 to BM3 causes an overcurrent when the auxiliary relay SR is turned on, which may cause the auxiliary relay SR to fuse.

[0053] Figure 3 is a diagram illustrating the calibration mode of the battery system 100. In Figure 3, battery module BM1 is selected as the calibration target. Battery modules BM2 and BM3, which are not selected as calibration targets, are omitted from the diagram.

[0054] As shown in Figure 3, in calibration mode, the control device 30 selects one DC / DC converter 1 from the plurality of DC / DC converters 1A to 1C contained in the battery module BM1 of the calibration target. In the example of Figure 3, the control device 30 selects DC / DC converter 1A. The selected DC / DC converter 1A is equivalent to the "first DC / DC converter".

[0055] Next, the control device 30 controls the bidirectional chopper 10A of the selected DC / DC converter 1A. On the other hand, the control device 30 stops the operation of the bidirectional choppers 10B and 10C of the other unselected DC / DC converters 1B and 1C.

[0056] The bidirectional chopper 10A, controlled by the control device 30, boosts the DC voltage of the battery pack BA and outputs the boosted voltage, i.e., 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 representing the detected value.

[0057] As shown by the thick solid line in Figure 3, the boost voltage of the bidirectional chopper 10A is applied to capacitor C1 of the bidirectional chopper 10B via the electric field line L. Voltage detector 12B detects the voltage between the terminals of capacitor C1 and outputs a signal representing the detected value. That is, voltage detector 12B detects the boost voltage of the bidirectional chopper 10A.

[0058] Similarly, the boost voltage of the bidirectional chopper 10A is applied to capacitor C1 of the bidirectional chopper 10C via the power line L. Voltage detector 12C detects the voltage between the terminals of capacitor C1 and outputs a signal representing the detected value. That is, voltage detector 12C detects the boost voltage of the bidirectional chopper 10A.

[0059] When all voltage detectors 12A to 12C are functioning normally, the detection values ​​of voltage detector 12A, voltage detector 12B, and voltage detector 12C are consistent. Conversely, if at least one of voltage detectors 12A to 12C is faulty, the detection values ​​of voltage detector 12A, voltage detector 12B, and voltage detector 12C are inconsistent. For example, if one voltage detector 12A to 12C is faulty while the other two are functioning normally, two of the three detection values ​​are consistent, and the remaining detection value is inconsistent with the other two.

[0060] After receiving the output signals from voltage detectors 12A-12C, control device 30 uses the detection values ​​from voltage detectors 12A-12C to calibrate voltage detector 12. Specifically, control device 30 first estimates the true value of the boost voltage in the bidirectional chopper 10A of DC / DC converter 1 (first DC / DC converter) by comparing the detection values ​​from voltage detectors 12A-12C. For example, control device 30 estimates the true value of the boost voltage of bidirectional chopper 10A by a majority vote of the detection values ​​from voltage detectors 12A-12C. As described above, if one voltage detector 12 among voltage detectors 12A-12C is faulty and the other two voltage detectors 12 are normal, two of the three detection values ​​are consistent, and the remaining detection value is inconsistent with these two detection values. In this case, control device 30 estimates that the two consistent detection values ​​are the true value of the boost voltage of bidirectional chopper 10A.

[0061] Next, the control device 30 uses the estimated true value of the boost voltage to calibrate at least one voltage detector 12. In the above case, the control device 30 calibrates the voltage detector 12 that outputs a remaining detection value. Specifically, the control device 30 uses the difference between the remaining detection value and the estimated true value of the boost voltage as the detection error of the voltage detector 12, and calculates a calibration value for the voltage detector 12 based on this detection error. After the calibration mode ends, the detection value of the voltage detector 12 is calibrated according to the above calibration value, thereby detecting the boost voltage of the corresponding bidirectional chopper 10.

[0062] Furthermore, the method for estimating the true value of the boost voltage in the bidirectional chopper 10 is not limited to majority voting, and well-known statistical processing methods can be used. For example, the true value of the boost voltage in the bidirectional chopper 10 can be estimated based on the average value and standard deviation of the detection values ​​of multiple voltage detectors 12.

[0063] Figure 4 is a flowchart illustrating the steps of the calibration process of the voltage detector 12 by the control device 30. As described above, the calibration process of the voltage detector 12 is performed when the PCS 3 stops operating.

[0064] As shown in Figure 4, in step S01, the control device 30 selects one battery module BM from the multiple battery modules BM1 to BM3 included in the battery system 100 to be the target of calibration. In step S02, the control device 30 further stops the operation of the multiple DC / DC converters 1A to 1C in the battery module BM that was not selected as the target of calibration. Furthermore, in calibration mode, the control device 30 keeps all auxiliary relays SR1 to SR3 in the ON state.

[0065] In step S03, the control device 30 selects one DC / DC converter 1 (the first DC / DC converter) from multiple DC / DC converters 1A to 1C in the battery module BM of the calibration target.

[0066] Next, the control device 30 controls the bidirectional chopper 10 of the selected DC / DC converter 1 through step S04. 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 representing the detected value.

[0067] In step S05, control device 30 stops the operation of the bidirectional choppers 10 of the remaining unselected DC / DC converters 1 in the battery module BM of the calibration target. In each of the remaining DC / DC converters 1, voltage detector 12 detects the voltage applied to capacitor C1 of the bidirectional chopper 10 via power line L and outputs a signal representing the detected value. That is, voltage detector 12 detects the boost voltage of the bidirectional chopper 10 of the first DC / DC converter 1.

[0068] In step S06, the control device 30 acquires a signal representing the detection value of the boost voltage of the bidirectional chopper 10 from multiple voltage detectors 12A-12C corresponding to the multiple DC / DC converters 1A-1C respectively.

[0069] In step S07, the control device 30 calibrates at least one voltage detector 12 among the multiple voltage detectors 12A-12C based on the detection values ​​of the multiple voltage detectors 12A-12C. In S07, the control device 30 estimates the true value of the boost voltage in the bidirectional chopper 10 of the DC / DC converter 1 (first DC / DC converter) by comparing the detection values ​​of the multiple voltage detectors 12A-12C. Then, the control device 30 uses the estimated true value of the boost voltage to calibrate at least one voltage detector 12.

[0070] As explained above, according to this embodiment, the voltage detector 12 configured in a battery system 100, which is configured to include multiple boost circuits (bidirectional choppers 10) connected in parallel, can be calibrated.

[0071] In the droop control of DC / DC converter 1, the boost voltage of bidirectional chopper 10 (boost circuit) is detected by voltage detector 12 to control the charging and discharging power of the corresponding battery pack B, so that the detected value of voltage detector 12 becomes the target voltage. In droop control, the detection error of voltage detector 12 leads to an error in the charging and discharging power of battery pack B. Therefore, in the battery system 100, the wiring design needs to take into account this power error. Since the wiring such as power lines L is designed to take into account the increase in power caused by the detection error of voltage detector 12, there is a concern about the large size of the wiring.

[0072] According to this disclosure, the detection error of the voltage detector 12 is reduced by calibrating the voltage detector 12, thereby suppressing errors in the power supplied during charging and discharging of the battery pack B. As a result, large-scale wiring is not required in the wiring design of the battery system 100.

[0073] The embodiments disclosed herein are merely illustrative in all respects and should not be construed as limiting the invention. The scope of this disclosure is not shown by the description of the above embodiments, but by the scope of the claims, which are intended to include all modifications within the same meaning and scope as the claims.

[0074] Explanation of reference numerals in the attached figures

[0075] 1. 1A~1C DC / DC 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 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 auxiliary relay.

Claims

1. A battery system for charging and discharging with an external system, comprising: a plurality of battery packs connected in parallel with the external system; a plurality of DC / DC converters respectively disposed corresponding to the plurality of battery packs, the plurality of DC / DC converters respectively performing DC-DC voltage conversion between their respective battery packs and the external system; and a control device for controlling the plurality of DC / DC converters, each of the plurality of DC / DC converters comprising: a boost circuit for boosting the DC voltage of the corresponding battery pack and outputting the boosted voltage, i.e., a boosted voltage, to the external system; and a voltage detector for detecting the boosted voltage, the battery system being configured to perform charging and discharging with the external system. The control device operates in a normal discharge mode and a calibration mode for calibrating the voltage detector. In the normal operation mode, the control device uses the detection value of the voltage detector to control the boost circuit for each of the plurality of DC / DC converters. In the calibration mode, the control device controls the boost circuit of a first DC / DC converter selected from the plurality of DC / DC converters, and stops the operation of the boost circuits of the remaining DC / DC converters. In the control of the boost circuit of the first DC / DC converter, the voltage detector of at least one of the plurality of DC / DC converters is calibrated based on the detection value of the voltage detector of the plurality of DC / DC converters.

2. The battery system according to claim 1, wherein, In the control of the boost circuit of the first DC / DC converter, the control device estimates the true value of the boost voltage in the boost circuit of the first DC / DC converter based on the detection values ​​of the voltage detectors of the plurality of DC / DC converters, and uses the estimated true value to correct the voltage detector of at least one DC / DC converter.

3. The battery system according to claim 1, wherein, The external system includes a power conversion device that performs bidirectional power conversion between the power system and the battery system, and the control device executes the correction mode when the power conversion device stops operating.

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 detection value of the voltage detector.

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