Storage battery control device and power storage system

Abstract

The storage battery control device performs: a first process of discharging the plurality of storage battery modules from a predetermined charge state by a predetermined discharge amount and recording module voltages and group currents; a second process of discharging the plurality of battery modules discharged by a predetermined discharge amount to a predetermined discharge state; a third process of charging the plurality of battery modules discharged to the predetermined discharge state by a predetermined charge amount; fourth processing: discharging the plurality of storage battery modules charged with the preset charging amount to a preset discharging state, and recording module voltage and group current; and a fifth process for generating voltage transition information when the plurality of battery modules are discharged on the basis of the module voltage and the group current recorded in the first process and the module voltage and the group current recorded in the fourth process.

Description

Technical Field

[0001] The present invention relates to a battery control device and an electricity storage system. Background Art

[0002] A state of health (SOH) estimation device is known which estimates the SOH representing the health of a battery (for example, see Patent Documents 1 and 2). In the SOH estimation device disclosed in Patent Document 1, when charging of the storage battery ends, the voltage of the storage battery is acquired from a voltage detection unit, measurement of the polarization recovery time is started, and when the difference between the acquired voltage and the voltage acquired again is equal to or greater than a predetermined voltage, measurement of the polarization recovery time ends. The SOH estimation device estimates the SOH of the storage battery based on the measured polarization recovery time.

[0003] The SOH estimation device described in Patent Document 2 determines the state of charge (SOC) based on an SOC-OCV curve representing the correlation between the state of charge (SOC) and the open circuit voltage (OCV), and estimates the SOH of the storage battery based on the determined SOC.

[0004] On the other hand, an electricity storage system including a bypass circuit for a plurality of corresponding storage batteries connected in series is known (for example, see Patent Document 3). In the electricity storage system described in Patent Document 3, when the storage battery reaches a fully discharged state or a fully charged state, the bypass circuit is controlled by a controller to switch the storage battery from a connected state to a bypass state.

[0005] Citation List

[0006] Patent Documents

[0007] Patent Document 1: JP2013-148452A

[0008] Patent Document 2: JP2021-71320A

[0009] Patent Document 3: JP2022-29299A Summary of the Invention

[0010] Technical Problem

[0011] In the electricity storage system described in Patent Document 3, it is assumed that the storage battery is discharged in order to obtain the SOC-OCV curve. In this assumption, when there are differences in the deterioration states of a plurality of storage batteries, when all the storage batteries reach the fully discharged state, the storage battery with a higher degree of deterioration reaches the fully discharged state earlier, and the storage battery is switched from the connected state to the bypass state. Therefore, when the storage battery is switched from the connected state to the bypass state, the SOC-OCV curve of the storage battery becomes discontinuous. Therefore, in order to obtain the SOC-OCV curve of each storage battery, it is necessary to perform discharging, and the operation interruption time of the electricity storage system becomes long.

[0012] In view of the above circumstances, an object of the present invention is to provide an electricity storage system and a battery control device that can efficiently obtain voltage change information about a battery in an electricity storage system including a battery pack in which a battery switches between a bypass state and a connected state.

[0013] Solution to the problem

[0014] The battery control device of the present invention is a battery control device for controlling an electricity storage system, the electricity storage system including: a battery pack including a plurality of batteries connected in series and a plurality of bypass circuits provided for each of the batteries and configured to switch the battery between a connected state and a bypass state; and a power converter configured to convert input and output power of the battery pack, and the battery control device performs: a first process of discharging a plurality of the batteries from a predetermined charge state by a predetermined discharge amount and recording the voltage of the battery and the current of the battery pack; a second process of discharging the plurality of the batteries that have been discharged by the predetermined discharge amount to a predetermined discharge state; a third process of charging the plurality of the batteries that have been discharged to the predetermined discharge state by a predetermined charge amount; a fourth process of discharging the plurality of the batteries that have been charged by the predetermined charge amount to the predetermined discharge state and recording the voltage of the battery and the current of the battery pack; and a fifth process of generating voltage change information representing voltage change when a plurality of the batteries are discharged based on the voltage of the battery and the current of the battery pack recorded in the first process and the voltage of the battery and the current of the battery pack recorded in the fourth process.

[0015] The battery control device of the present invention is a battery control device for controlling an electricity storage system. The electricity storage system includes: a battery pack including a plurality of batteries connected in series and a plurality of bypass circuits provided for each of the batteries and configured to switch the battery between a connected state and a bypass state; and a power converter configured to convert the input and output power of the battery pack. The battery control device performs: a first process of charging a plurality of the batteries from a predetermined discharge state by a predetermined charge amount and recording the voltage of the battery and the current of the battery pack; a second process of charging the plurality of the batteries charged with the predetermined charge amount to a predetermined charge state; a third process of discharging the plurality of the batteries charged to the predetermined charge state by a predetermined discharge amount; a fourth process of charging the plurality of the batteries discharged by the predetermined discharge amount to the predetermined charge state and recording the voltage of the battery and the current of the battery pack; and a fifth process of generating voltage change information representing the voltage change when charging a plurality of the batteries based on the voltage of the battery and the current of the battery pack recorded in the first process and the voltage of the battery and the current of the battery pack recorded in the fourth process.

[0016] The electricity storage system of the present invention is an electricity storage system including: a battery pack including a plurality of batteries connected in series and a plurality of bypass circuits provided for each of the batteries and configured to switch the battery between a connected state and a bypass state; a power converter configured to convert the input and output power of the battery pack; and a battery control device configured to control the bypass circuit and the power converter. Among them, the battery control device performs: a first process of discharging a plurality of the batteries from a predetermined charge state by a predetermined discharge amount and recording the voltage of the battery and the current of the battery pack; a second process of discharging the plurality of the batteries discharged by the predetermined discharge amount to a predetermined discharge state; a third process of charging the plurality of the batteries discharged to the predetermined discharge state by a predetermined charge amount; a fourth process of discharging the plurality of the batteries charged with the predetermined charge amount to the predetermined discharge state and recording the voltage of the battery and the current of the battery pack; and a fifth process of generating voltage change information representing the voltage change when discharging a plurality of the batteries based on the voltage of the battery and the current of the battery pack recorded in the first process and the voltage of the battery and the current of the battery pack recorded in the fourth process.

[0017] The energy storage system of the present invention is an energy storage system, comprising: a battery pack including a plurality of batteries connected in series and a plurality of bypass circuits provided for each of the batteries and configured to switch the batteries between a connected state and a bypass state; a power converter configured to convert the input and output power of the battery pack; and a battery control device configured to control the bypass circuits and the power converter, wherein the battery control device performs: a first process of charging a plurality of the batteries from a predetermined discharge state by a predetermined charge amount and recording the voltage of the batteries and the current of the battery pack; a second process of charging the plurality of the batteries charged with the predetermined charge amount to a predetermined charge state; a third process of discharging the plurality of the batteries charged to the predetermined charge state by a predetermined discharge amount; a fourth process of charging the plurality of the batteries discharged by the predetermined discharge amount to the predetermined charge state and recording the voltage of the batteries and the current of the battery pack; and a fifth process of generating voltage change information representing the voltage change during charging of the plurality of the batteries based on the voltage of the batteries and the current of the battery pack recorded in the first process and the voltage of the batteries and the current of the battery pack recorded in the fourth process.

[0018] Advantageous Effects of the Invention

[0019] According to the present invention, in an energy storage system including a battery pack in which batteries are switched between a bypass state and a connected state, voltage change information of the batteries can be efficiently obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a circuit diagram schematically showing an energy storage system including a battery control device according to an embodiment of the present invention.

[0021] Figure 2 shows Figure 1 a flowchart of a process in which the system controller shown obtains a discharge capacity-module voltage curve representing the correlation between the discharge capacity and the voltage of a battery module.

[0022] Figure 3 shows during the execution of Figure 2 a graph showing the correlation between the discharge capacity and the voltage of a battery module during the process shown in the flowchart.

[0023] Figure 4 shows during the execution of Figure 2 a graph showing the correlation between the discharge capacity and the voltage of a battery module during the process shown in the flowchart.

[0024] Figure 5 shows by Figure 2The graph of the discharge capacity-module voltage curve generated by the process shown in the flowchart.

[0025] Figure 6 is a graph showing Figure 2 The graph of the discharge capacity-module voltage curve generated by the process shown in the flowchart.

[0026] Figure 7 is a graph showing Figure 2 The graph of the discharge capacity-module voltage curve generated by the process shown in the flowchart.

[0027] Figure 8 is a graph showing Figure 1 The flowchart of the process in which the system controller shown obtains the charge capacity-module voltage curve representing the correlation between the charge capacity and the voltage of the battery module.

[0028] Figure 9 is a graph showing the correlation between the charge capacity and the voltage of the battery module during the execution of Figure 8 the process shown in the flowchart.

[0029] Figure 10 is a graph showing the correlation between the charge capacity and the voltage of the battery module during the execution of Figure 8 the process shown in the flowchart.

[0030] Figure 11 is a graph showing Figure 8 The graph of the charge capacity-module voltage curve generated by the process shown in the flowchart.

[0031] Figure 12 is a graph showing Figure 8 The graph of the charge capacity-module voltage curve generated by the process shown in the flowchart.

[0032] Figure 13 is a graph showing Figure 8 The graph of the charge capacity-module voltage curve generated by the process shown in the flowchart. DETAILED DESCRIPTION

[0033] Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the embodiments described below, and the embodiments can be appropriately modified without departing from the scope of the present invention. In the embodiments to be described below, a part of the structure may not be described or shown in the drawings, and regarding the technical details omitted, as long as they are not contradictory to the content described below, publicly known or well-known technologies will be appropriately applied.

[0034] Figure 1 is a circuit diagram schematically showing the power storage system 1 including the battery control device 100 according to an embodiment of the present invention. AsFigure 1 As shown, the power storage system 1 includes m groups (m is an integer of 2 or greater) of battery packs STR1 to STRm, a group bus 3, m power converters PC1 to PCm, and a battery control device 100. The m groups of battery packs STR1 to STRm are connected to each other via the m power converters PC1 to PCm and the group bus 3, and are connected to an external system (not shown). The power storage system 1 is a stationary or in-vehicle power supply.

[0035] Each of the battery packs STR1 to STRm includes n (n is an integer of 2 or greater) battery modules M1 to Mn connected in series. Although not particularly limited, the battery modules M1 to Mn in this embodiment are obtained by recycling used batteries, and there are differences in the degradation states of the battery modules M1 to Mn. The battery modules M1 to Mn are secondary batteries such as lithium-ion batteries and lithium-ion capacitors.

[0036] The battery modules M1 to Mn are charged using the power supplied from the external system through the group bus 3 and the power converters PC1 to PCm, and the charged power is discharged through the power converters PC1 to PCm and the group bus 3 to supply power to the external system.

[0037] The external system includes a load, a generator, etc. When the power storage system 1 is a stationary power supply, household appliances, a commercial power system, etc. are used as the load, and a solar photovoltaic power generation system, etc. is used as the generator. On the other hand, when the power storage system 1 is an in-vehicle power supply, a drive motor, an air conditioner, various in-vehicle electrical components, etc. are used as the load. The drive motor is both a load and a generator.

[0038] The battery packs STR1 to STRm may include n battery cells or battery packs connected in series instead of the n battery modules M1 to Mn connected in series. The power storage system 1 may include a bypass circuit that bypasses each battery cell or each battery pack.

[0039] The power converters PC1 to PCm are DC / DC converters or DC / AC converters and are connected to the group bus 3. The positive electrode of the starting battery module M1 and the negative electrode of the terminal battery module Mn are connected to each of the power converters PC1 to PCm.

[0040] When the battery packs STR1 to STRm are being charged, the power converters PC1 to PCm convert the voltage input from the group bus 3 and output the converted voltage to the multiple battery modules M1 to Mn. On the other hand, when the battery packs STR1 to STRm are discharging, the power converters PC1 to PCm convert the voltage input from the multiple battery modules M1 to Mn and output the converted voltage to the group bus 3. When the current flowing through the group bus 3 is an alternating current, each of the power converters PC1 to PCm is provided with a synchronization unit that follows the instantaneous value changes.

[0041] Each of the battery packs STR1 to STRm includes n voltage sensors 12, current sensors 13, and n bypass circuits B1 to Bn. The voltage sensors 12 are connected between the positive and negative terminals of each of the battery modules M1 to Mn. The voltage sensors 12 measure the inter-terminal voltage of each of the battery modules M1 to Mn.

[0042] The current sensors 13 are provided in the current paths of the battery packs STR1 to STRm. The current sensors 13 measure the charging and discharging currents (hereinafter referred to as group current) of the battery packs STR1 to STRn.

[0043] The bypass circuits B1 to Bn are provided for each of the battery modules M1 to Mn. Each of the bypass circuits B1 to Bn includes a bypass line BL and switches S1 and S2. The bypass line BL is a power line that bypasses each of the battery modules M1 to Mn. The switch S1 is provided on the bypass line BL. The switch S1 is, for example, a semiconductor switch, a mechanical switch, or a relay. The switch S2 is provided between the positive terminal of each of the battery modules M1 to Mn and one end of the bypass line BL. The switch S2 is, for example, a semiconductor switch, a mechanical switch, or a relay.

[0044] The battery module M1 at the starting end and the battery module Mn at the terminal end are connected to an external system through each of the power converters PC1 to PCm and the group bus 3. When the switches S1 in all of the bypass circuits B1 to Bn are open and the switches S2 are closed, all of the battery modules M1 to Mn are connected in series to the external system. On the other hand, when the switch S2 in any one of the bypass circuits B1 to Bn is open and the switch S1 is closed, the battery modules M1 to Mn corresponding to the bypass circuits B1 to Bn are bypassed.

[0045] The battery control device 100 includes n group controllers 102 and a system controller 101. The system controller 101 controls power converters PC1 to PCm. On the other hand, the group controllers 102 control bypass circuits B1 to Bn and send information about the states (opening and closing of switches S1 and S2) of the bypass circuits B1 to Bn to the system controller 101. The group controllers 102 receive the detection signals of each voltage sensor 12 and each current sensor 13 and send the detection signals to the system controller 101.

[0046] Based on the pre-stored SOC-OCV curve (discharge capacity-module voltage curve or charge capacity-module voltage curve described later) and the detection signals of the voltage sensor 12 and the current sensor 13, the system controller 101 estimates battery states such as SOH or SOC of the battery modules M1 to Mn (hereinafter referred to as state estimation). In particular, in this embodiment, the system controller 101 performs a discharge process or a charge process of the target battery groups STR1 to STRm that requires obtaining basic data for state estimation such as SOH or SOC for the purpose of obtaining the SOC-OCV curve as basic data. The system controller 101 can perform only the discharge process to obtain the discharge capacity-module voltage curve, or can perform only the charge process to obtain the charge capacity-module voltage curve. In addition, the system controller 101 can perform both the discharge process for obtaining the discharge capacity-module voltage curve and the charge process for obtaining the charge capacity-module voltage curve.

[0047] Here, a predetermined range of the discharge capacity of the battery modules M1 to Mn is defined as SOC = 100%. The SOC can be obtained by comparing the measured or estimated voltage of the battery modules M1 to Mn (corresponding to OCV, hereinafter referred to as module voltage) with the SOC-OCV curve.

[0048] The current total capacity of the battery modules M1 to Mn can be calculated by converting the charge and discharge capacity within the predetermined range of the SOC-OCV curve to SOC = 100%. In addition, the SOH can be calculated by obtaining the ratio of the initial total capacity to the current total capacity of the battery modules M1 to Mn, or by obtaining the capacity ratio within the predetermined range of the initial SOC-OCV curve and the current SOC-OCV curve. By comparing the initial SOC-OCV curve with the current SOC-OCV curve, faults, installation defects, etc. of the battery modules M1 to Mn can also be determined.

[0049] Figure 2 is shown Figure 1The flowchart of the process in which the system controller 101 shown obtains a discharge capacity-module voltage curve (SOC-OCV curve) representing the correlation between the discharge capacity and voltage of the battery modules M1 to Mn. Figure 3 and Figure 4 is a graph showing the correlation between the discharge capacity and voltage of the battery modules M1 to Mn during the process shown in the flowchart of Figure 2 . Further, Figure 5 and Figure 7 is a graph showing the discharge capacity-module voltage curve generated by the process shown in the flowchart of Figure 2 .

[0050] First, in step S1 shown in Figure 2 , the system controller 101 determines target battery packs STR1 to STRm for which basic data for state estimation such as SOH or SOC needs to be updated. Next, in step S2, the system control 101 controls the corresponding power converters PC1 to PCm to input power to the target battery packs STR1 to STRn. At this time, the system controller 101 brings all the battery modules M1 to Mn of the target battery packs STR1 to STRm into a fully charged state. Further, whenever the voltage of each of the battery modules M1 to Mn rises to a predetermined end-of-charge voltage, the group controller 102 switches the battery modules M1 and Mn from the connected state to the bypass state through the bypass circuits B1 to Bn corresponding to the battery modules M1 to Mn. The state in which the voltage of each of the battery modules M1 to Mn is the predetermined end-of-charge voltage is Figure 3 the state shown in (1) in

[0051] Here, as shown in Figure 3 , there are differences in the discharge capacity of the battery modules M1 to Mn. Among the battery modules M1 to Mn, the higher the degree of deterioration, the smaller the discharge capacity and the shorter the time from the fully charged state to the fully discharged state.

[0052] Next, in step S3, the system controller 101 sends an instruction to the group controller 102 to switch all the battery modules M1 to Mn of the target battery packs STR1 to STRm from the bypass state to the connected state. Accordingly, all the battery modules M1 to Mn of the target battery packs STR1 to STRm are connected in series.

[0053] Next, in step S4, the system controller 101 starts to record the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13. Here, the recording of the voltages and currents from step S5 to step S7 is referred to as the first recording. On the other hand, the recording of the voltages and currents from step S12 to step S15 is referred to as the second recording.

[0054] Next, in step S5, the system controller 101 controls the corresponding power converters PC1 to PCm to start discharging the target battery packs STR1 to STRm at a constant current and a low current.

[0055] Next, in step S6, the system controller 101 determines whether the discharge amounts of all the battery modules M1 to Mn of the target battery packs STR1 to STRm have reached a predetermined discharge amount based on the cumulative value of the discharge currents detected by the current sensors 13. Figure 3 The state shown in (2) is the state where the discharge amounts of all the battery modules M1 to Mn have reached the predetermined discharge amount. If it is determined to be yes in step S6, the process proceeds to step S7. If it is determined to be no in step S6, step S6 is repeated.

[0056] Here, the "predetermined discharge amount" is set such that an overlapping range is generated between the discharge capacity-module voltage curve obtained in the first recording and the discharge capacity-module voltage curve obtained in the second recording. During the discharge of the "predetermined discharge amount", the battery modules M1 to Mn that reach the discharge end voltage are switched from the connected state to the bypass state through the bypass circuits B1 to Bn. In this case, the discharge capacity-module voltage curve obtained in the first recording and the discharge capacity-module voltage curve obtained in the second recording may be discontinuous. Therefore, it is preferably set such that during the discharge of the "predetermined discharge amount" (during the execution of the first recording), the battery modules M1 to Mn do not switch from the connected state to the bypass state. On the other hand, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the discharge of the "predetermined discharge amount", processes such as smoothing or extrapolation are performed to generate a continuous discharge capacity-module voltage curve.

[0057] Next, in step S7, the system controller 101 stops recording (the first recording) the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13.

[0058] Next, in step S8, the system controller 101 controls the corresponding power converters PC1 to PCm to output power from all the battery modules M1 to Mn of the target battery packs STR1 to SRTm. At this time, the system controller 101 causes all the battery modules M1 to Mn of the target battery packs STR1 to STRm to enter a fully discharged state. In addition, whenever the voltage of each of the battery modules M1 to Mn drops to a predetermined end-of-discharge voltage, the group controller 102 switches the battery modules M1 and Mn from the connected state to the bypass state through the bypass circuits B1 to Bn corresponding to the battery modules M1 to Mn. The state where the voltage of each of the battery modules M1 to Mn is the predetermined end-of-discharge voltage is Figure 3 the state shown in (3) of Figure 4 and (3) of, that is, the fully discharged state of each of the battery modules M1 to Mn.

[0059] Next, in step S9, the system controller 101 sends an instruction to the group controller 102 to switch all the battery modules M1 to Mn of the target battery packs STR1 to STRm from the bypass state to the connected state. Therefore, all the battery modules M1 to Mn of the target battery packs STR1 to STRm are connected in series.

[0060] Next, in step S10, the system controller 101 controls the corresponding power converters PC1 to PCm to start charging the target battery packs STR1 to STRm with a constant current.

[0061] Next, in step S11, the system controller 101 determines whether the charge amount of all the battery modules M1 to Mn of the target battery packs STR1 to STRm has reached a predetermined charge amount based on the cumulative value of the charging current detected by the current sensor 13. Figure 4 The state shown in (4) of is the state where the charge amount of all the battery modules M1 to Mn has reached the predetermined charge amount.

[0062] Here, the "predetermined charge amount" is set such that an overlapping range is generated between the discharge capacity-module voltage curves obtained in the first record and the discharge capacity-module voltage curves obtained in the second record. The battery modules M1 to Mn that reach the end-of-charge voltage during charging with the "predetermined charge amount" are switched from the connected state to the bypass state through the bypass circuits B1 to Bn. In this case, the discharge capacity-module voltage curves obtained in the first record and the discharge capacity-module voltage curves obtained in the second record may be discontinuous. Therefore, it is preferable to set the "predetermined charge amount" such that the battery modules M1 to Mn do not switch from the connected state to the bypass state during charging with the "predetermined charge amount". On the other hand, when the battery modules M1 to Mn are switched from the connected state to the bypass state during charging with the "predetermined charge amount", processes such as smoothing or extrapolation are performed to generate a continuous discharge capacity-module voltage curve.

[0063] If it is determined to be YES in step S11, the process proceeds to step S12. If it is determined to be NO in step S11, step S11 is repeated. In step S12, the system controller 101 starts recording (the second record) the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13.

[0064] Next, in step S13, the system controller 101 controls the corresponding power converters PC1 to PCm to start discharging the target battery packs STR1 to STRm with a constant current and a low current. Here, when the battery modules M1 to Mn are switched from the connected state to the bypass state during charging in step S11, the system controller 101 maintains the bypass state of the battery modules M1 to Mn until the middle of step S14 described later.

[0065] Next, in step S14, the system controller 101 determines whether the discharge of all the battery modules M1 to Mn of the target battery packs STR1 to STRm is completed based on the cumulative value of the discharge current detected by the current sensor 13. Figure 4 The state shown in (5) in is the fully discharged state of all the battery modules M1 to Mn.

[0066] Here, when the battery modules M1 to Mn are switched from the connected state to the bypass state during charging in step S11, the system controller 101 maintains the battery modules M1 to Mn in the bypass state until the remaining discharge capacities of the battery modules M1 to Mn and the other battery modules M1 to Mn are equal to each other.

[0067] If the determination in step S14 is yes, the process proceeds to step S15. If the determination in step S14 is no, step S14 is repeated. In step S15, the system controller 101 stops recording (second recording) the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13.

[0068] Next, in step S16, the system controller 101 generates a discharge capacity-module voltage curve for each of the battery modules M1 to Mn based on the first and second recordings of each of the battery modules M1 to Mn. Specifically, the system controller 101 generates a discharge capacity-module voltage curve in the high SOC region based on the first recording of each of the battery modules M1 to Mn. On the other hand, the system controller 101 generates a discharge capacity-module voltage curve in the low SOC region based on the second recording of each of the battery modules M1 to Mn. The system controller 101 synthesizes the discharge capacity-module voltage curve in the high SOC region and the discharge capacity-module voltage curve in the low SOC region to generate a discharge capacity-module voltage curve representing the transition of the voltage from the fully charged state to the fully discharged state.

[0069] Here, as described above, it is also conceivable that the battery modules M1 to Mn switch from the connected state to the bypass state during the execution of the first or second recording. In this case, the system controller 101 performs processing such as smoothing or extrapolation on the boundary between the range corresponding to the first recording and the range corresponding to the second recording in the discharge capacity-module voltage curve, and generates a continuous discharge capacity-module voltage curve as shown in Figures 5 to 7 Thus, Figure 3 The processing shown in the flowchart in [] ends.

[0070] As described above, the battery control device 100 of the present embodiment performs the following first to fifth processes.

[0071] (First process)

[0072] A plurality of battery modules M1 to Mn are discharged by a predetermined discharge amount from the fully charged state (predetermined charging state), and the module voltage and the pack current are recorded. (Second process)

[0073] The plurality of battery modules M1 to Mn that have been discharged by the predetermined discharge amount are discharged to the fully discharged state (predetermined discharge state). (Third process)

[0074] The plurality of battery modules M1 to Mn discharged to the fully discharged state (predetermined discharge state) are charged by a predetermined charge amount. (Fourth process)

[0075] A plurality of battery modules M1 to Mn that have been charged with a predetermined charge amount are discharged to a fully discharged state (predetermined discharge state), and the voltages of the battery modules M1 to Mn and the currents of the battery packs STR1 to STRm are recorded. (Fifth process)

[0076] Based on the module voltages and pack currents recorded in the first process and the module voltages and pack currents recorded in the fourth process, voltage transition information representing the voltage transition when the plurality of battery modules M1 to Mn are discharged is generated.

[0077] Therefore, in the middle of executing the discharge mode to obtain the voltage transition information representing the voltage transition when the plurality of battery modules M1 to Mn are discharged, it is possible to prevent the battery modules M1 to Mn from switching from the connected state to the bypass state. Thus, even when the discharge mode is executed for each of the battery packs STR1 to STRm, it is possible to prevent a discontinuous range from occurring in the voltage transition information from the fully charged state (predetermined charge state) to the fully discharged state (predetermined discharge state). As described above, it is possible to efficiently obtain the voltage transition information when the plurality of battery modules M1 to Mn are discharged, and the interruption time of the operation of the power storage system 1 can be shortened.

[0078] The predetermined discharge amount and the predetermined charge amount are set such that a part of the range (high SOC region) corresponding to the module voltages and pack currents recorded in the first process in the voltage transition information during discharge and a part of the range (low SOC region) corresponding to the module voltages and pack currents recorded in the fourth process in the voltage transition information during discharge overlap each other.

[0079] Therefore, during the execution of the first process, when the battery modules M1 to Mn switch from the connected state to the bypass state at a discharge capacity corresponding to the overlapping range of the high SOC region and the low SOC region, the recorded information regarding the fourth process can be used within the overlapping range. On the other hand, during the execution of the third process, when the battery modules M1 to Mn switch from the connected state to the bypass state at a discharge capacity corresponding to the overlapping region of the high SOC region and the low SOC region, the recorded information regarding the first process can be used within the overlapping range. Thus, a continuous discharge capacity - module voltage curve can be obtained as the voltage transition information when the plurality of battery modules M1 to Mn are discharged.

[0080] Furthermore, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the execution of the third process, the battery control device 100 maintains the bypass state of the battery modules M1 to Mn until the discharge capacities of the battery modules M1 to Mn in the bypass state and the other battery modules M1 to Mn in the connected state in the fourth process become equal. Therefore, in the fourth process, the plurality of battery modules M1 to Mn can be simultaneously discharged to the fully discharged state (predetermined discharge state).

[0081] Figure 8 is a flowchart showing Figure 1 the process in which the system controller 101 acquires a charge capacity-module voltage curve (SOC-OCV curve) representing the correlation between the charge capacity and voltage of the battery modules M1 to Mn. Figure 9 and Figure 10 is a graph showing the correlation between the charge capacity and voltage of the battery modules M1 to Mn during the process shown in the flowchart of Figure 8 . Further, Figures 11 to 13 is a graph showing the charge capacity-module voltage curve generated by the process shown in the flowchart of Figure 8 .

[0082] First, in step S21, the system controller 101 determines the target battery packs STR1 to STRm for which the basic data for state estimation such as SOH or SOC needs to be updated. Next, in step S22, the system control 101 controls the corresponding power converters PC1 to PCm to output power from the target battery packs STR1 to STRm. At this time, the system controller 101 brings all the battery modules M1 to Mn of the target battery packs STR1 to STRm into a fully discharged state. Further, whenever the voltage of each of the battery modules M1 to Mn rises to a predetermined discharge end voltage, the group controller 102 switches the battery modules M1 and Mn from the connected state to the bypass state through the bypass circuits B1 to Bn corresponding to the battery modules M1 to Mn. The state in which the voltage of each of the battery modules M1 to Mn is the predetermined discharge end voltage is Figure 9 the state shown in (1) of

[0083] Here, as Figure 9 shown, there are differences in the charge capacity of the battery modules M1 to Mn. Among the battery modules M1 to Mn, the higher the degree of deterioration, the smaller the charge capacity and the shorter the time from the fully discharged state to the fully charged state.

[0084] Next, in step S23, the system controller 101 sends an instruction to the group controller 102 to switch all the battery modules M1 to Mn of the target battery packs STR1 to STRm from the bypass state to the connected state. Accordingly, all the battery modules M1 to Mn of the target battery packs STR1 to STRm are connected in series.

[0085] Next, in step S24, the system controller 101 starts to record the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13. Here, the recording of the voltages and currents from step S25 to step S27 is referred to as the first recording. On the other hand, the recording of the voltages and currents from step S32 to step S35 is referred to as the second recording.

[0086] Next, in step S25, the system controller 101 controls the corresponding power converters PC1 to PCm to start charging the target battery packs STR1 to STRm with a constant current and a low current.

[0087] Next, in step S26, the system controller 101 determines whether the charge amounts of all the battery modules M1 to Mn of the target battery packs STR1 to STRm have reached a predetermined charge amount based on the cumulative value of the charging currents detected by the current sensors 13. Figure 9 The state shown in (2) in [reference] is the state where the charge amounts of all the battery modules M1 to Mn have reached the predetermined charge amount. If it is determined to be yes in step S26, the process proceeds to step S27. If it is determined to be no in step S26, step S26 is repeated.

[0088] Here, the "predetermined charge amount" is set such that an overlapping range is generated between the charge capacity-module voltage curve obtained in the first recording and the discharge capacity-module voltage curve obtained in the second recording. During the charging with the "predetermined charge amount", the battery modules M1 to Mn that reach the charge end voltage are switched from the connected state to the bypass state through the bypass circuits B1 to Bn. In this case, the charge capacity-module voltage curve obtained in the first recording and the charge capacity model voltage curve obtained in the second recording may be discontinuous. Therefore, it is preferably set such that during the charging with the "predetermined charge amount" (during the execution of the first recording), the battery modules M1 to Mn do not switch from the connected state to the bypass state. On the other hand, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the charging with the "predetermined charge amount", processes such as smoothing or extrapolation are performed to generate a continuous discharge capacity-module voltage curve.

[0089] Next, in step S27, the system controller 101 stops recording (the first recording) the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13.

[0090] Next, in step S28, the system controller 101 controls the corresponding power converters PC1 to PCm to input power to all the battery modules M1 to Mn of the target battery packs STR1 to SRTm. At this time, the system controller 101 causes all the battery modules M1 to Mn of the target battery packs STR1 to STRm to enter the fully charged state. In addition, whenever the voltage of each of the battery modules M1 to Mn rises to a predetermined end-of-charge voltage, the group controller 102 switches the battery modules M1 and Mn from the connected state to the bypass state through the bypass circuits B1 to Bn corresponding to the battery modules M1 to Mn. The state where the voltage of each of the battery modules M1 to Mn is the predetermined end-of-charge voltage is Figure 9 (3) in Figure 10 and (3) in

[0091] , that is, the fully charged state of each of the battery modules M1 to Mn.

[0092] Next, in step S29, the system controller 101 sends an instruction to the group controller 102 to switch all the battery modules M1 to Mn of the target battery packs STR1 to STRm from the bypass state to the connected state. Therefore, all the battery modules M1 to Mn of the target battery packs STR1 to STRm are connected in series.

[0092] Next, in step S30, the system controller 101 controls the corresponding power converters PC1 to PCm to start discharging the target battery packs STR1 to STRm at a constant current.

[0093] Next, in step S31, the system controller 101 determines whether the discharge amount of all the battery modules M1 to Mn of the target battery packs STR1 to STRm has reached a predetermined discharge amount based on the cumulative value of the discharge current detected by the current sensor 13. Figure 10 The state shown in (4) in

[0094] Here, the "predetermined discharge amount" is set so as to create an overlapping range between the charge capacity-module voltage curve obtained in the first recording and the charge capacity-module voltage curve obtained in the second recording. The battery modules M1 to Mn that reach the end-of-discharge voltage during the discharge of the "predetermined discharge amount" are switched from the connected state to the bypass state through the bypass circuits B1 to Bn. In this case, the charge capacity-module voltage curve obtained in the first recording and the charge capacity-module voltage curve obtained in the second recording may be discontinuous. Therefore, it is preferable to set the "predetermined discharge amount" so that the battery modules M1 to Mn do not switch from the connected state to the bypass state during the discharge of the "predetermined discharge amount". On the other hand, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the discharge of the "predetermined discharge amount", processes such as smoothing or extrapolation are performed to generate a continuous charge capacity-module voltage curve.

[0095] If it is determined to be "yes" in step S31, the process proceeds to step S32. If it is determined to be "no" in step S31, step S31 is repeated. In step S32, the system controller 101 starts recording (second recording) the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13.

[0096] Next, in step S33, the system controller 101 controls the corresponding power converters PC1 to PCm to start charging the target battery packs STR1 to STRm with a constant current and a low current. Here, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the discharge in step S31, the system controller 101 maintains the bypass state of the battery modules M1 to Mn until the middle of step S34 described later.

[0097] Next, in step S34, the system controller 101 determines whether the charging of all the battery modules M1 to Mn of the target battery packs STR1 to STRm is completed based on the cumulative value of the charging current detected by the current sensor 13. Figure 10 The state shown in (5) in [ ] is the fully charged state of all the battery modules M1 to Mn.

[0098] Here, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the discharge in step S31, the system controller 101 maintains the battery modules M1 to Mn in the bypass state until the remaining charge capacities of the battery modules M1 to Mn and the other battery modules M1 to Mn are equal to each other.

[0099] If it is determined to be yes in step S34, the process proceeds to step S35. If it is determined to be no in step S34, step S34 is repeated. In step S35, the system controller 101 stops recording (the second recording) the voltages of the battery modules M1 to Mn detected by the voltage sensors 12 of the target battery packs STR1 to STRm and the currents detected by the current sensors 13.

[0100] Next, in step S36, the system controller 101 generates a charge capacity-module voltage curve for each of the battery modules M1 to Mn based on the first recording and the second recording of each of the battery modules M1 to Mn. Specifically, the system controller 101 generates a charge capacity-module voltage curve in the low SOC region based on the first recording of each of the battery modules M1 to Mn. On the other hand, the system controller 101 generates a charge capacity-module voltage curve in the high SOC region based on the second recording of each of the battery modules M1 to Mn. The system controller 101 synthesizes the charge capacity-module voltage curve in the low SOC region and the charge capacity-module voltage curve in the high SOC region to generate a charge capacity-module voltage curve representing the transition of the voltage from the fully discharged state to the fully charged state.

[0101] Here, as described above, it is also conceivable that during the execution of the first recording or the second recording, the battery modules M1 to Mn are switched from the connected state to the bypass state. In this case, the system controller 101 performs processing such as smoothing or extrapolation on the boundary between the range corresponding to the first recording and the range corresponding to the second recording in the charge capacity-module voltage curve, and generates a continuous charge capacity-module voltage curve as shown in Figures 11 to 13 Thus, Figure 8 the processing shown in the flowchart in

[0102] As described above, the battery control device 100 of the present embodiment performs the following first to fifth processes.

[0103] (First process)

[0104] A plurality of battery modules M1 to Mn are charged with a predetermined charge amount from the fully discharged state (predetermined discharge state), and the module voltage and the pack current are recorded. (Second process)

[0105] The plurality of battery modules M1 to Mn charged with the predetermined charge amount are charged to the fully charged state (predetermined charge state). (Third process)

[0106] The plurality of battery modules M1 to Mn charged to the fully charged state (predetermined charge state) are discharged by a predetermined discharge amount. (Fourth process)

[0107] A plurality of battery modules M1 to Mn that have discharged a predetermined discharge amount are charged to a fully charged state (predetermined charge state), and the module voltage and the pack current are recorded. (Fifth process)

[0108] Based on the module voltage and the pack current recorded in the first process and the module voltage and the pack current recorded in the fourth process, voltage transition information representing the voltage transition during charging of the plurality of battery modules M1 to Mn is generated.

[0109] Therefore, in the middle of executing the charging mode to obtain the voltage transition information representing the voltage transition during charging of the plurality of battery modules M1 to Mn, it is possible to prevent the battery modules M1 to Mn from switching from the connected state to the bypass state. Therefore, even when the charging mode is executed for each battery pack STR1 to STRm, it is possible to prevent a discontinuous range from being generated in the voltage transition information from the fully discharged state (predetermined discharge state) to the fully charged state (predetermined charge state). As described above, it is possible to efficiently obtain the voltage transition information during charging of the plurality of battery modules M1 to Mn, and it is possible to shorten the interruption time of the operation of the power storage system 1.

[0110] The predetermined charge amount and the predetermined discharge amount are set such that a part of the range (low SOC region) corresponding to the module voltage and the pack current recorded in the first process in the voltage transition information during charging and a part of the range (high SOC region) corresponding to the module voltage and the pack current recorded in the fourth process in the voltage transition information during charging overlap each other.

[0111] Therefore, during the execution of the first process, when the battery modules M1 to Mn switch from the connected state to the bypass state at a charge capacity corresponding to the overlapping range of the low SOC region and the high SOC region, the recorded information regarding the fourth process can be used within the overlapping range. On the other hand, during the execution of the third process, when the battery modules M1 to Mn switch from the connected state to the bypass state at a charge capacity corresponding to the overlapping range of the low SOC region and the high SOC region, the recorded information regarding the first process can be used within the overlapping range. Therefore, a continuous charge capacity - module voltage curve can be obtained as the voltage transition information during charging of the plurality of battery modules M1 to Mn.

[0112] In addition, when the battery modules M1 to Mn are switched from the connected state to the bypass state during the execution of the third process, the battery control device 100 maintains the bypass state of the battery modules M1 to Mn until the charge capacities of the battery modules M1 to Mn in the bypass state and the other battery modules M1 to Mn in the connected state are equal in the fourth process. Therefore, in the fourth process, the plurality of battery modules M1 to Mn can be charged to the fully charged state (predetermined charge state) simultaneously.

[0113] Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and modifications can be made without departing from the gist of the present invention, and publicly known or well-known technologies can be appropriately combined.

[0114] For example, in the above embodiment, the "predetermined charging state" described in the claims is defined as the "fully charged state". However, the "predetermined charging state" is not limited to the "fully charged state", and includes a state where the remaining charging capacity is small and close to the fully charged state, a state where the remaining charge amount exceeds a small range and is far from being fully charged, and the like. In addition, in the above embodiment, the "predetermined discharging state" described in the claims is defined as the "fully discharged state". However, the "predetermined discharging state" is not limited to the "fully discharged state", and includes a state where the remaining discharging capacity is small and close to the fully discharged state, a state where the remaining discharging capacity exceeds a small range and is far from being fully discharged, and the like.

[0115] Here, the features of the above-described embodiments of the battery control device and the power storage system according to the present invention will be briefly summarized and listed in the following [1] to [8].

[0116] [1] A battery control device (100) for controlling a power storage system (1), the power storage system including: a battery pack (STR1 to STRm) including a plurality of batteries (M1 to Mn) connected in series and a plurality of bypass circuits (B1 to Bn) provided for each of the batteries and configured to switch the batteries between a connected state and a bypass state; and a power converter (PC1 to PCm) configured to convert the input and output power of the battery pack, the battery control device (100) performing:

[0117] A first process of discharging a plurality of the batteries by a predetermined discharge amount from a predetermined charging state and recording the voltage of the batteries and the current of the battery pack;

[0118] A second process of discharging the plurality of batteries that have been discharged by the predetermined discharge amount to a predetermined discharge state;

[0119] A third process of charging the plurality of batteries that have been discharged to the predetermined discharge state by a predetermined charge amount;

[0120] A fourth process of discharging the plurality of batteries that have been charged by the predetermined charge amount to the predetermined discharge state and recording the voltage of the batteries and the current of the battery pack; and

[0121] Fifth process: Based on the voltage of the storage battery and the current of the battery pack recorded in the first process, and the voltage of the storage battery and the current of the battery pack recorded in the fourth process, generate voltage change information representing the voltage change when a plurality of the storage batteries discharge.

[0122] [2] The battery control device according to [1], wherein the predetermined discharge amount and the predetermined charge amount are set such that a part of the range corresponding to the voltage of the storage battery and the current of the battery pack recorded in the first process in the voltage change information, and a part corresponding to the voltage of the storage battery and the current of the battery pack recorded in the fourth process in the voltage change information overlap each other.

[0123] [3] The battery control device according to [1] or [2], wherein when the storage battery is switched from the connected state to the bypass state through the bypass circuit during the execution of the third process, the bypass state of the storage battery is maintained until the discharge capacities of the storage battery in the bypass state and the storage battery in the connected state in the fourth process are equal to each other.

[0124] [4] A battery control device for controlling an energy storage system, the energy storage system including: a battery pack including a plurality of storage batteries connected in series and a plurality of bypass circuits provided for each of the storage batteries and configured to switch the storage battery between a connected state and a bypass state; and a power converter configured to convert the input and output power of the battery pack, the battery control device performs:

[0125] First process: Charge a plurality of the storage batteries from a predetermined discharge state by a predetermined charge amount, and record the voltage of the storage battery and the current of the battery pack;

[0126] Second process: Charge the plurality of the storage batteries charged with the predetermined charge amount to a predetermined charge state;

[0127] Third process: Discharge the plurality of the storage batteries charged to the predetermined charge state by a predetermined discharge amount;

[0128] Fourth process: Charge the plurality of the storage batteries discharged by the predetermined discharge amount to the predetermined charge state, and record the voltage of the storage battery and the current of the battery pack; and

[0129] Fifth process: Based on the voltage of the storage battery and the current of the battery pack recorded in the first process, and the voltage of the storage battery and the current of the battery pack recorded in the fourth process, generate voltage change information representing the voltage change during charging of multiple storage batteries.

[0130] [5] The battery control device according to [4], wherein the predetermined charge amount and the predetermined discharge amount are set such that a part of the range corresponding to the voltage of the storage battery and the current of the battery pack recorded in the first process in the voltage change information and a part corresponding to the voltage of the storage battery and the current of the battery pack recorded in the fourth process in the voltage change information overlap each other.

[0131] [6] The battery control device according to [4] or [5], wherein when the storage battery is switched from the connected state to the bypass state through the bypass circuit during the execution of the third process, the bypass state of the storage battery is maintained until the charge capacities of the storage battery in the bypass state and the storage battery in the connected state in the fourth process are equal to each other.

[0132] [7] An energy storage system, comprising:

[0133] A battery pack, which includes a plurality of storage batteries connected in series and a plurality of bypass circuits provided for each of the storage batteries and configured to switch the storage battery between a connected state and a bypass state;

[0134] A power converter configured to convert the input and output power of the battery pack; and

[0135] A battery control device configured to control the bypass circuit and the power converter, wherein,

[0136] The battery control device performs:

[0137] First process: Discharge a plurality of the storage batteries from a predetermined charge state by a predetermined discharge amount, and record the voltage of the storage battery and the current of the battery pack;

[0138] Second process: Discharge the plurality of the storage batteries that have been discharged by the predetermined discharge amount to a predetermined discharge state;

[0139] Third process: Charge the plurality of the storage batteries discharged to the predetermined discharge state by a predetermined charge amount;

[0140] Fourth process: discharging a plurality of the storage batteries charged with the predetermined charge amount to the predetermined discharge state, and recording the voltage of the storage battery and the current of the storage battery pack; and

[0141] Fifth process: generating voltage transition information representing the voltage transition when a plurality of the storage batteries are discharged, based on the voltage of the storage battery and the current of the storage battery pack recorded in the first process, and the voltage of the storage battery and the current of the storage battery pack recorded in the fourth process.

[0142] [8] A power storage system, comprising:

[0143] A storage battery pack including a plurality of storage batteries connected in series and a plurality of bypass circuits provided for each of the storage batteries and configured to switch the storage battery between a connected state and a bypass state;

[0144] A power converter configured to convert the input and output power of the storage battery pack; and

[0145] A storage battery control device configured to control the bypass circuit and the power converter, wherein

[0146] the storage battery control device performs:

[0147] First process: charging a plurality of the storage batteries from a predetermined discharge state by a predetermined charge amount, and recording the voltage of the storage battery and the current of the storage battery pack;

[0148] Second process: charging a plurality of the storage batteries charged with the predetermined charge amount to a predetermined charge state;

[0149] Third process: discharging a plurality of the storage batteries charged to the predetermined charge state by a predetermined discharge amount;

[0150] Fourth process: charging a plurality of the storage batteries discharged by the predetermined discharge amount to the predetermined charge state, and recording the voltage of the storage battery and the current of the storage battery pack; and

[0151] Fifth process: generating voltage transition information representing the voltage transition when a plurality of the storage batteries are charged, based on the voltage of the storage battery and the current of the storage battery pack recorded in the first process, and the voltage of the storage battery and the current of the storage battery pack recorded in the fourth process.

[0152] This application is based on Japanese Patent Application No. 2022-191255 filed on November 30, 2022, the content of which is incorporated herein by reference.

[0153] Industrial applicability

[0154] According to the present invention, an object of the present invention is to provide an electricity storage system and a battery control device that can efficiently obtain voltage change information about a battery in an electricity storage system including a battery pack in which a battery switches between a bypass state and a connected state. The present invention having such an effect is useful for a battery control device and an electricity storage system.

[0155] List of reference symbols

[0156] 1: Electricity storage system

[0157] 100: Battery control device

[0158] B1 to Bn: Bypass circuit

[0159] M1 to Mn: Battery module (battery)

[0160] PC1 to PCm: Power converter

[0161] STR1 to STRm: Battery pack

Claims

1. A battery control device for controlling an electricity storage system, the electricity storage system comprising: a battery pack including a plurality of batteries connected in series, and a plurality of bypass circuits provided for each of the batteries and configured to switch the battery between a connected state and a bypass state; and a power converter configured to convert input and output power of the battery pack, the battery control device performing: a first process of discharging a plurality of the batteries from a predetermined charged state by a predetermined discharge amount and recording the voltage of the battery and the current of the battery pack; a second process of discharging the plurality of the batteries that have been discharged by the predetermined discharge amount to a predetermined discharged state; a third process of charging the plurality of the batteries discharged to the predetermined discharged state by a predetermined charge amount; a fourth process of discharging the plurality of the batteries charged by the predetermined charge amount to the predetermined discharged state and recording the voltage of the battery and the current of the battery pack; and a fifth process of generating voltage change information representing the voltage change when a plurality of the batteries are discharged, based on the voltage of the battery and the current of the battery pack recorded in the first process, and the voltage of the battery and the current of the battery pack recorded in the fourth process.

2. The battery control device according to claim 1, wherein the predetermined discharge amount and the predetermined charge amount are set such that a part of a range corresponding to the voltage of the battery and the current of the battery pack recorded in the first process in the voltage change information, and a part of a range corresponding to the voltage of the battery and the current of the battery pack recorded in the fourth process in the voltage change information overlap each other.

3. The battery control device according to claim 1 or 2, wherein when the battery is switched from the connected state to the bypass state through the bypass circuit during the execution of the third process, the bypass state of the battery is maintained until the discharge capacities of the battery in the bypass state and the battery in the connected state in the fourth process become equal.

4. A battery control device for controlling an electricity storage system, the electricity storage system comprising: a battery pack including a plurality of batteries connected in series, and a plurality of bypass circuits provided for each of the batteries and configured to switch the battery between a connected state and a bypass state; and a power converter configured to convert input and output power of the battery pack, the battery control device performing: a first process of charging a plurality of the batteries from a predetermined discharged state by a predetermined charge amount and recording the voltage of the battery and the current of the battery pack; a second process of charging the plurality of the batteries charged by the predetermined charge amount to a predetermined charged state; a third process of discharging the plurality of the batteries charged to the predetermined charged state by a predetermined discharge amount; Fourth process: Charge a plurality of the storage batteries that have discharged the predetermined discharge amount to the predetermined charge state, and record the voltage of the storage battery and the current of the storage battery pack; And Fifth process: Generate voltage transition information representing the voltage transition during charging of a plurality of the storage batteries based on the voltage of the storage battery and the current of the storage battery pack recorded in the first process, and the voltage of the storage battery and the current of the storage battery pack recorded in the fourth process.

5. The storage battery control device according to claim 4, wherein the predetermined charge amount and the predetermined discharge amount are set such that a part of the range corresponding to the voltage of the storage battery and the current of the storage battery pack recorded in the first process in the voltage transition information and a part of the range corresponding to the voltage of the storage battery and the current of the storage battery pack recorded in the fourth process in the voltage transition information overlap each other.

6. The storage battery control device according to claim 4 or 5, wherein when the storage battery is switched from the connected state to the bypass state through the bypass circuit during the execution of the third process, the bypass state of the storage battery is maintained until the charge capacities of the storage battery in the bypass state and the storage battery in the connected state in the fourth process are equal to each other.

7. An electricity storage system, comprising: A storage battery pack including a plurality of storage batteries connected in series, and a plurality of bypass circuits provided for each of the storage batteries and configured to switch the storage battery between a connected state and a bypass state; A power converter configured to convert the input and output power of the storage battery pack; And A storage battery control device configured to control the bypass circuit and the power converter, wherein the storage battery control device performs: First process: Discharge a plurality of the storage batteries from a predetermined charge state by a predetermined discharge amount, and record the voltage of the storage battery and the current of the storage battery pack; Second process: Discharge a plurality of the storage batteries that have discharged the predetermined discharge amount to a predetermined discharge state; Third process: Charge a plurality of the storage batteries discharged to the predetermined discharge state by a predetermined charge amount; Fourth process: Discharge a plurality of the storage batteries that have been charged by the predetermined charge amount to the predetermined discharge state, and record the voltage of the storage battery and the current of the storage battery pack; and Fifth process: Generate voltage transition information representing the voltage transition during discharging of a plurality of the storage batteries based on the voltage of the storage battery and the current of the storage battery pack recorded in the first process, and the voltage of the storage battery and the current of the storage battery pack recorded in the fourth process.

8. An electricity storage system, comprising: A storage battery pack including a plurality of storage batteries connected in series and a plurality of bypass circuits provided for each of the storage batteries and configured to switch the storage battery between a connected state and a bypass state; A power converter configured to convert the input and output power of the storage battery pack; And A battery control device configured to control the bypass circuit and the power converter, wherein, the battery control device performs: a first process of charging a plurality of the batteries from a predetermined discharge state by a predetermined charge amount and recording the voltage of the batteries and the current of the battery pack; a second process of charging the plurality of the batteries charged with the predetermined charge amount to a predetermined charge state; a third process of discharging the plurality of the batteries charged to the predetermined charge state by a predetermined discharge amount; a fourth process of charging the plurality of the batteries discharged by the predetermined discharge amount to the predetermined charge state and recording the voltage of the batteries and the current of the battery pack; and a fifth process of generating voltage transition information representing the voltage transition when charging a plurality of the batteries based on the voltage of the batteries and the current of the battery pack recorded in the first process and the voltage of the batteries and the current of the battery pack recorded in the fourth process.

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