Battery control system and battery control method

Abstract

A battery control system (1) comprises: a pressure application means (16) that applies pressure to a battery module (2) by pressing the battery module (2) along the lamination direction of battery cells (21) each having a negative electrode including lithium and a solid electrolyte; a controller (10) that adjusts the value of pressure by controlling the pressure application means (16); and a discharging means (15) that performs balancing of remaining discharge capacities among the battery cells (21) in the battery module (2). The controller (10) starts a first pressure application control in which pressure is increased to a prescribed pressure or higher, by the pressure application means (16), before the balancing is started.

Description

[Technical Field]

[0001] The present invention relates to a battery control system and a battery control method. [Background technology]

[0002] A lithium-ion secondary battery is known that comprises an electrode body having a positive electrode and a negative electrode containing a Si-containing negative electrode active material, and a surface pressure control unit that controls the surface pressure applied to the electrode body in a predetermined direction (see, for example, Patent Document 1). The surface pressure control unit of this lithium-ion secondary battery controls the amplitude of the surface pressure that fluctuates with charging and discharging to 3.8 MPa or less. Specifically, this amplitude is the difference between the maximum and minimum values ​​of the surface pressure observed when charging and discharging from SOC 0% to 100% (see, for example, Patent Document 1 (paragraph

[0014] )). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-61749 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, conventional technology does not consider pressure control for secondary batteries when balancing them. Balancing is performed, for example, when the vehicle's control system is stopped and then started again, and the vehicle's control system is stopped, for example, when the vehicle is parked.

[0005] Even when the control system is shut down, the secondary battery self-discharges, causing it to contract. This contraction can prevent the application of appropriate pressure to the secondary battery, potentially causing its electrical resistance to fall outside the optimal range for charging and discharging. In such cases, the accuracy of the secondary battery balancing deteriorates.

[0006] The problem that this invention aims to solve is to provide a battery control system and a battery control method that can improve the accuracy of balancing battery cells. [Means for solving the problem]

[0007] The present invention solves the above problem by discharging the battery cells to balance the remaining discharge capacity between them, and by pressing the battery module along the stacking direction of the battery cells before the balancing begins, thereby increasing the pressure applied to the battery module to a predetermined pressure or higher. [Effects of the Invention]

[0008] According to the present invention, the accuracy of balancing battery cells can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing a battery control system according to an embodiment of the present invention. [Figure 2] Figure 2 is a flowchart showing the procedure for a battery control method according to an embodiment of the present invention. [Figure 3] Figure 3 is a graph showing the relationship between the pressure applied to the battery cell and the resistance value of the battery cell. [Figure 4] Figure 4 is a graph showing the change in pressure over time in the battery control method according to an embodiment of the present invention. [Figure 5] Figure 5 is a graph showing the change in pressure over time in a modified battery control method of the present invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the battery control system 1 of this embodiment.

[0011] As shown in Figure 1, the battery control system 1 comprises a controller 10, a voltage sensor 11, a current sensor 12, a temperature sensor 13, a DC-DC converter 14, a discharge means 15, a pressure application mechanism 16, and a pressure sensor 17. In this embodiment, the controller 10 is the "control means" and "remaining discharge capacity" in the present invention. Calculation This corresponds to an example of a "means" and a "determination means." Furthermore, the pressure sensor 17 in this embodiment corresponds to an example of a "pressure acquisition means" in the present invention.

[0012] Controller 10 is a battery control unit (BCU). Controller 10 consists of memory such as ROM or RAM, and a processor such as a CPU. Based on the detected voltage detected by the voltage sensor 11, the detected current detected by the current sensor 12, the detected temperature detected by the temperature sensor 13, etc., Controller 10 manages the state of the battery module 2 and determines the SOC usage range of the battery module 2 according to the state of the battery module 2.

[0013] Furthermore, as will be described later, this controller 10 controls the discharge means 15 and the pressure application mechanism 16.

[0014] The voltage sensor 11 is a sensor for detecting the voltage between the terminals of the battery module 2. The voltage sensor 11 is connected between the wiring connected to the positive and negative terminals of the battery module 2. The current sensor 12 is a sensor for detecting the input and output current of the battery module 2. The current sensor 12 is connected to the wiring connected to either the positive or negative terminal of the battery module 2. The temperature sensor 13 is provided in the battery module 2. The temperature sensor 13 is a sensor for detecting the temperature of the battery module 2.

[0015] The DCDC converter 14 is a power conversion device that converts the voltage input from the battery module 2 into a predetermined voltage and outputs power to a load such as a motor. The DCDC converter 14 is also a power conversion device that converts the voltage input from a load such as a motor or a charging device into a predetermined voltage and outputs power to the battery module 2. This DCDC converter 14 is controlled by the controller 10. The battery module 2 is connected to the input side of the DCDC converter 14, and a load is connected to the output side of the DCDC converter 14. The load is a power grid including a motor inverter or the like. That is, the battery module 2 is connected to the load via the DCDC converter 14. << >><<

[0016] >><< >>The discharging means 15 is a circuit for individually discharging a plurality of battery cells 21 included in the battery module 2. The discharging means 15 is electrically connected to the positive and negative electrodes of the battery cell 21, and one discharging means 15 is electrically connected to one battery cell 21. This discharging means 15 may be a general discharging means used for balancing that discharges the battery cell 21 having a remaining discharge capacity larger than the remaining discharge capacities of the other battery cells 21. In the present embodiment, as this balancing, passive balancing is performed in which discharging is performed so that the remaining discharge capacities of the other battery cells 21 are combined with the remaining discharge capacity of the battery cell 21 having the smallest remaining discharge capacity. However, active balancing may be performed as the balancing. << >><<

[0017] >><< >>The discharging means 15 in the present embodiment is not particularly limited, but for example, it has at least a resistor and a switch electrically connected in series to this resistor. The switch is controlled to be turned on and off by the controller 10, and when the controller 10 turns on the switch, the battery cell 21 discharges. << >><<

[0018] >><< >>The pressure application mechanism 16 applies pressure to the battery module 2 by pressing the battery module 2 along the stacking direction of the battery cells 21 in the battery module 2. The pressure application mechanism 16 in the present embodiment includes a motor driver circuit 161, a motor 162, a gearbox 163, a pressure transmission body 164, a fixed end plate 165, a movable end plate 166, and a plurality of shafts 167. The movable end plate 166 in the present embodiment corresponds to an example of the "pressure application means" in the present invention.

[0019] The motor driver circuit 161 operates the motor 162. The motor driver circuit 161 controls the driving of the operation of the motor 162 based on a control signal from the controller 10. of Control the driving of the operation.

[0020] The motor 162 has a first drive shaft 162a. This motor 162 rotationally drives the first drive shaft 162a in response to the output from the motor driver circuit 161.

[0021] The gearbox 163 is connected to the first drive shaft 162a and converts the rotational drive of the first drive shaft 162a into the drive of the pressure transmission body 164 in the stacking direction.

[0022] The pressure transmission body 164 moves up and down by the driving force transmitted through the gearbox 163. This pressure transmission body 164 includes a second drive shaft 164a and a pressure transmission plate 164b. The second drive shaft 164a is connected to the gearbox 163, and the rotational drive of the first drive shaft 162a of the motor 162 is transmitted by the gearbox 163. The pressure transmission plate 164b is a plate that moves along the stacking direction as the second drive shaft 164a rotates. In the present embodiment, by moving the pressure transmission plate 164b downward in the drawing, the pressure applied to the battery module 2 can be controlled in the increasing direction, and by moving the pressure transmission plate 164b upward in the drawing, the pressure applied to the battery module 2 can be controlled in the decreasing direction.

[0023] The fixed end plate 165 and the movable end plate 166 are a pair of plate-like members connected to each other by a plurality of shafts 167. The fixed end plate 165 is fixed to the shafts 167 and supports the battery module 2. On the other hand, the movable end plate 166 is not fixed to the shafts 167 and is movable along the extending direction of the shafts 167, and pressurizes the battery module 2 from above in accordance with the force transmitted from the pressure transmission body 164. Furthermore, this movable end plate 166 can move along the stacking direction in response to the expansion and contraction of the battery module 2 due to charging and discharging, and the expansion and contraction of the battery module 2 due to changes in the pressure applied to the battery module 2 by the movable end plate 166.

[0024] The pressure sensor 17 is a sensor capable of measuring the pressure applied to the battery module 2. This pressure sensor 17 can output the detected pressure to the controller 10.

[0025] The battery module 2 is electrically connected to a charging device. The charging device connected to the battery cell 21 is, for example, a device for charging the battery module 2 installed in an electric vehicle or a hybrid vehicle. Charging the vehicle-mounted battery module 2 is performed by taking out the charging cable from the charging device, attaching the charging gun at the end of the charging cable to the connector of the vehicle's charging port, and then operating the charging start switch. The controller 10 manages the state of charge (SOC) of the battery cell 21 contained in the battery module 2, and controls the DC-DC converter 14 and the charging device respectively so that the charge state of the battery module 2 reaches the target charge state.

[0026] As described above, battery module 2 is electrically connected to loads such as motors. The loads are devices that operate using the power of battery module 2, and include motors that are the driving source of the vehicle, as well as auxiliary equipment such as air conditioners and lights. Discharging of battery module 2 is performed under the control of controller 10 in response to system requests or external power requests. System requests correspond to commands from an on-board computer such as an ECU while the vehicle is running. Regarding external power requests, for example, when an external device such as a mobile terminal commands the air conditioner to be operated before the vehicle starts running via a timer setting, so that the interior of the vehicle reaches an appropriate temperature when the vehicle starts running, the command from the external device corresponds to an external power request.

[0027] Furthermore, battery modules 2 installed in electric vehicles and hybrid vehicles may be used for Vehicle Grid Integration (VGI). VGI is a technology that connects electric vehicles and hybrid vehicles equipped with battery modules 2 to the grid and supplies the power stored in the battery modules 2 to the grid (load) via the power network.

[0028] The battery cell 21 contained in the battery module 2 comprises at least a positive electrode, a solid electrolyte, and a negative electrode. The positive electrode contains at least a positive electrode active material capable of releasing and absorbing alkali metals such as lithium (Li), sodium (Na), or potassium (K), and is not particularly limited, but preferably contains a positive electrode active material containing sulfur. As the solid electrolyte, for example, a sulfide solid electrolyte or an oxide solid electrolyte can be used, but the use of a sulfide solid electrolyte is preferred. The negative electrode may contain lithium, and for example, it is preferable that it contains lithium metal.

[0029] The following describes a battery control method for a battery module 2 using such a battery control system 1. Figure 2 is a flowchart showing the procedure of the battery control method of this embodiment. The battery control method of this embodiment is repeatedly executed at predetermined intervals, particularly when the vehicle is started up and balancing of the battery cells 21 is performed.

[0030] First, in step S1, the controller 10 estimates the State of Charge (SOC) of each battery cell 21 based on the open-circuit voltage of each battery cell 21. The SOC can be estimated using a general method that uses the open-circuit voltage and the integrated charge and discharge charge of each battery cell 21.

[0031] In step S2, the controller 10 calculates the difference between the maximum value (highest SOC) and the minimum value (lowest SOC) within each SOC of each battery cell 21. Then, it compares the calculated difference with a predetermined difference threshold.

[0032] If the difference calculated in step S2 is greater than or equal to the difference threshold, balancing (capacity adjustment) must be performed. Therefore, in step S3, the amount of discharge during balancing for each battery cell 21 is calculated from the difference between the SOC of each battery cell 21 and the minimum SOC, such that the remaining discharge capacity of each battery cell 21 can be made approximately equal. For example 、1 Capacity at 00% SOC is Q max In a [Ah] battery, the remaining discharge capacity of the battery cell 21 with the lowest SOC is Q min If the remaining capacity of a specific battery cell 21 included in the battery module 2 is Q1[Ah], then the discharge amount of that battery cell 21 during balancing is Q1-Q min It becomes [Ah].

[0033] In step S4, the discharge time T for each battery cell is calculated from the calculated discharge amount. dis,x Calculate (x=1,2,···,n) (where n is the number of battery cells 21). Discharge time T dis,x This can be calculated for each battery cell 21, for example, the discharge amount of a particular battery cell 21 is Q1-Q min If the value is [Ah], the discharge time is calculated using the resistance value R[Ω] of the resistor of the discharge means 15 connected to each battery cell 21 and the current battery voltage V[V], and is (Q1-Q min ) × R ÷ V [h].

[0034] In step S5, the controller 10 turns on the power to the pressure application mechanism 16. In other words, in this embodiment, the controller 10 outputs an ON signal to the motor driver circuit 161. The pressurization control of the battery module by the pressure application mechanism 16, which is performed between steps S5 and S13, corresponds to an example of the "first pressurization control" in the present invention.

[0035] In step S6, the controller 10 increases the pressure applied to the battery module 2 to a predetermined pressure. That is, before balancing begins, the controller 10 moves the movable end plate 166 downward (in the direction of contraction of the battery module 2), increasing the pressure applied to the battery module 2. This reduces the electrical resistance of the battery cells 21.

[0036] In step S7, the controller 10 determines from the value detected by the pressure sensor 17 whether the pressure applied to the battery module 2 has reached a predetermined pressure. In this embodiment, the predetermined pressure is the performance requirement pressure P1. The pressure applied to the battery cell 21 is approximately the same as the pressure applied to the battery module 2.

[0037] Figure 3 is a graph showing the relationship between the pressure applied to the battery cell 21 and the resistance value of the battery cell 21. As shown in Figure 3, the resistance value of the battery cell 21 decreases as the pressure applied to the battery module 2 increases. Here, the performance requirement pressure P1 is the pressure at which the electrical resistance of the battery cell 21 becomes equal to a predetermined threshold value. This threshold is the maximum value of electrical resistance within the range of electrical resistance at which the battery cell 21 can input and output the charge and discharge power necessary to operate the vehicle's control system.

[0038] The performance requirement pressure P1 can be determined experimentally as follows: Since the greater the resistance of a battery cell, the less power it can charge and discharge, pressure is applied to the battery cell to reduce its resistance until it can output the power necessary to operate the vehicle's control system (including the balancing system). The performance requirement pressure P1 can be determined by experimentally finding the minimum pressure at which the power necessary to operate the control system can be output, based on the relationship between pressure and power.

[0039] Furthermore, this performance requirement pressure P1 is greater than the seismic resistance requirement pressure P0. The seismic resistance requirement pressure P0 is the minimum pressure at which the battery module 2 will not fall out from between the fixed end plate 165 and the movable end plate 166, even if external forces such as shock or vibration are applied to the battery module 2.

[0040] The specified pressure may be greater than the performance requirement pressure P1, or it may be slightly less than the performance requirement pressure P1, provided that it is small enough that it does not negatively affect the accuracy of the balancing.

[0041] Furthermore, in this embodiment, the pressure applied to the battery module 2 (the pressure applied to the battery cell 21) is detected by the pressure sensor 17, but this is not limited to this. The pressure may be estimated without using the pressure sensor 17.

[0042] Specifically, for example, if the negative electrode is a lithium metal negative electrode, the thickness of the battery cell changes approximately in proportion to the State of Charge (SOC). Therefore, the thickness of the battery module changes approximately in proportion to the charge and discharge amount of the battery module. Furthermore, the amount of change in the thickness of the battery module due to motor operation is determined by the gear ratio and screw pitch in the pressure application mechanism, as well as the amount of motor operation. Therefore, if the relationship between the difference between the change in the thickness of the battery module due to charge and discharge amount and the change in the thickness of the battery module due to motor operation, and the pressure is experimentally obtained, the pressure can be estimated from the time-series changes in the motor command value and SOC based on this relationship.

[0043] Returning to FIG. 2, when it is determined that the pressure applied to the battery module 2 has reached a predetermined pressure, in step S8, the controller 10 permits charge and discharge by balancing each battery cell 21 of the battery module 2. That is, the controller 10 uses the discharging means 15 to discharge each battery cell 21 by the discharging means 15 for balancing. At this time, the first pressurization control has not yet been completed, and the pressurization operation on the battery module 2 is continuing. That is, in the present embodiment, the discharging means 15 starts balancing before the first pressurization control is completed based on an instruction from the controller 10. The discharge of the battery cells 21 by the discharging means 15 executed between step S8 and step S13 in the present embodiment corresponds to an example of "balancing" in the present invention.

[0044] FIG. 4 is a graph showing the change over time of the pressure in the battery control method of the present embodiment. The solid line in the graph indicates the change over time of the pressure. As shown in FIG. 4, after starting the first pressurization control, the pressure applied to the battery module 2 is gradually increased, and when the pressure reaches the performance requirement pressure P1, balancing is started. In FIG. 4, after the start of balancing, the pressure is constant, but this is due to the contraction of the battery module 2 by balancing. As will be described below, actually, the pressurization by the first pressurization control continues even after the start of balancing.

[0045] In step S7, when it is determined that the pressure applied to the battery module 2 has not reached the predetermined pressure, the current battery control is terminated, and after a predetermined period, the battery control is restarted from step S1.

[0046] Returning to FIG. 2, in step S9, if the cumulative discharge time by balancing of each battery cell 21 has not reached T dis,x the controller 10 continues discharging until the cumulative discharge time by balancing of each battery cell 21 reaches T dis,x

[0047] ​In step S10, the controller 10 calculates the amount of shrinkage (thickness reduction) of the battery module 2 per unit time based on the total discharge current of each battery cell 21 calculated in step S3. The amount of shrinkage of the battery module 2 per unit time can be determined experimentally. For example, the amount of discharge current of one battery cell 21 and the amount of thickness reduction of that battery cell 21 per unit time relative to that discharge current can be measured in advance, and the relationship between the amount of discharge current and the amount of thickness reduction of one battery cell 21 per unit time can be determined. Then, the controller 10 calculates the amount of thickness reduction of each battery cell 21 per unit time based on the amount of discharge current of each battery cell 21 contained in the battery module 2, and calculates the sum of the amount of thickness reduction of each battery cell 21 per unit time. This sum is the amount of shrinkage of the battery module 2 per unit time.

[0048] In step S11, the controller 10 moves the movable end plate 166 of the pressure application mechanism 16 in the contraction direction of the battery module 2 (downward in Figure 1) at the same rate as the decrease in battery thickness per unit time. As a result, as shown in Figure 4, the pressure applied to the battery module 2 from the movable end plate 166 during balancing is kept almost constant, meeting the performance requirements. pressure The pressure will no longer fall significantly below P1. Furthermore, the amount of movement of the movable end plate 166 may be greater than the amount of contraction of the battery module 2; in this case, the pressure applied to the battery module 2 will be greater than the performance requirement pressure P1.

[0049] In step S12, the controller 10 calculates the cumulative discharge time by balancing all battery cells 21 to T dis,x Upon reaching this point, it is determined whether the SOC of all battery cells 21 is equal to the minimum SOC mentioned above.

[0050] In step S12, if the controller 10 determines that the SOC of all battery cells 21 is equal to the minimum SOC mentioned above, then in step S13, the controller 10 determines that balancing of all battery cells 21 is complete.

[0051] If it is determined in step S12 that balancing of all battery cells 21 has not been completed, the current battery control is terminated, and the battery control is restarted from step S1 after a predetermined period.

[0052] In step S2, if the controller 10 determines that the calculated difference is less than the difference threshold, in step S14, the pressure of the battery cell 21 is increased to a predetermined pressure (performance requirement pressure P1). The pressurization control performed in step S14 corresponds to an example of the "second pressurization control" in the present invention.

[0053] In step S15, the controller 10 determines from the value detected by the pressure sensor 17 whether the pressure applied to the battery module 2 has reached a predetermined pressure.

[0054] In step S15, if the controller 10 determines that the pressure applied to the battery module 2 has reached a predetermined pressure, the controller 10 permits charging and discharging of the battery cell 21. In this case, balancing of the battery cell 21 is not required, so the charging and discharging of the battery cell 21 refers to charging and discharging in response to a load such as the vehicle's drive motor.

[0055] In step S15, if the controller 10 determines that the pressure applied to the battery module 2 has not reached a predetermined pressure, it terminates the current battery control and restarts the battery control from step S1 after a predetermined cycle.

[0056] Conventionally, due to the pressure application mechanism, control method, and self-discharge during long periods of inactivity, it was sometimes not possible to apply the appropriate pressure for charging and discharging to the battery module when the vehicle's control system started up. Furthermore, in conventional control systems, the BMS adjusted the capacity of the battery cells immediately after startup in order to make the battery cells ready for charging and discharging as quickly as possible. As a result, charging and discharging occurred outside the appropriate pressure range, and even if discharge was performed for a predetermined time, the discharge amount would deviate due to resistance losses, resulting in a loss of the desired discharge amount and a decrease in balancing accuracy.

[0057] In contrast, with the battery control system and battery control method of this embodiment, before balancing begins, a first pressurization control is initiated in which the pressure applied to the battery module 2 by the movable end plate 166 is increased to a predetermined pressure or higher to reduce the electrical resistance of the battery cells 21. Therefore, charging and discharging can be performed within an appropriate pressure range. Thus, the accuracy of balancing can be improved.

[0058] Furthermore, in this embodiment, by setting a predetermined pressure to the performance requirement pressure P1, the electrical resistance of the battery cell 21 can be made more suitable for balancing, thereby improving the accuracy of balancing.

[0059] Furthermore, in this embodiment, the discharge means 15 starts balancing before the first pressurization control is completed, thus shortening the time required for the vehicle startup process.

[0060] Furthermore, in this embodiment, if balancing is started before the first pressurization control is completed, the amount of movement of the movable end plate 166 in the first pressurization control is set to be the same as the amount of contraction of the battery module 2 due to balancing. This suppresses the increase in the electrical resistance of the battery cells 21 and reduces the increase in resistance loss during balancing. As a result, the startup time can be shortened and the accuracy of balancing can be improved.

[0061] Furthermore, in this embodiment, even if balancing is deemed unnecessary, a second pressurization control (see step S14 in Figure 2) is performed to increase the pressure applied to the battery module 2 to a predetermined pressure or higher. This allows the vehicle's control system to be activated after the resistance value of the battery module 2 has been set to an appropriate value.

[0062] In the above embodiment, balancing is started before the first pressurization control is completed, but the system is not limited to this, and balancing may be started after the first pressurization control is completed.

[0063] Figure 5 is a graph showing the change in pressure over time in a modified battery control method of this embodiment. As shown in Figure 5, in this modified embodiment, in steps S6 to S7 of the flowchart in Figure 2, the pressure applied to the battery module 2 is increased to a first pressure P2 which is greater than the performance requirement pressure P1.

[0064] The first pressure P2 is a pressure that takes into account the amount of contraction of the battery module 2 due to the discharge of the battery cells 21 during balancing. Specifically, the first pressure P2 is set higher the larger the sum of the remaining discharge capacities of each battery cell 21. In other words, the first pressure P2 is set higher the larger the reduction in the thickness of the battery module 2 due to balancing.

[0065] The difference P2-P1 between the first pressure P2 and the performance requirement pressure P1 corresponds to the additional pressure applied according to the amount of shrinkage of the battery module 2. This difference P2-P1 is calculated based on the total discharge current of each battery cell 21 calculated in step S3, and the amount of shrinkage (thickness reduction) of the battery module 2 due to balancing is calculated. The relationship between this amount of shrinkage and the reduction in pressure applied to the battery module 2 can be calculated experimentally in advance, and the calculated reduction in pressure is taken as the difference P2-P1.

[0066] By starting balancing after the pressure reaches the first pressure P2 set in this manner, it is possible to prevent the pressure from falling below the performance requirement pressure P1 during balancing, as shown in Figure 5. Therefore, with the battery control system and battery control method in this modified example, even if the discharge amount due to balancing fluctuates, it is possible to prevent the pressure from dropping and the battery resistance from increasing. Furthermore, even if the pressure drops during balancing, it is possible to prevent the pressure from dropping to a level where the resistance loss becomes unacceptable. [Explanation of Symbols]

[0067] 1…Battery control system 10…Controller 11…Voltage sensor 12...Current sensor 13…Temperature sensor 14…DC-DC converter 15...Discharge means 16…Pressure application mechanism 161…Motor driver circuit 162...motor 162a...First drive shaft 163... Gearbox 164... Pressure transmission body 164a...Second drive shaft 164b... Pressure transmission plate 165…Fixed end plate 166…Movable end plate 167... Shaft 17…Pressure sensor 2…Battery module

Claims

1. A battery control system for controlling a battery module comprising a plurality of stacked battery cells, each having a solid electrolyte and a lithium-containing negative electrode, A pressure applying means for applying pressure to the battery module by pressing the battery module along the stacking direction of the battery cells, A control means that adjusts the value of the pressure by controlling the pressure application means, A residual discharge capacity calculation means for calculating the residual discharge capacity of each of the aforementioned battery cells, The battery cell is discharged to perform balancing of the remaining discharge capacity between the battery cells, The control means is a battery control system that initiates a first pressurization control by the pressure application means to increase the pressure to a predetermined pressure or higher before the balancing is initiated.

2. In the battery control system according to claim 1, The aforementioned predetermined pressure is the performance requirement pressure. The performance requirement pressure is the pressure at which the electrical resistance of the battery cell equals the threshold value. The threshold is the maximum value of the electrical resistance within the range of electrical resistance of the battery cell that enables the battery cell to input and output the charge and discharge power necessary to operate the vehicle's control system.

3. In the battery control system according to claim 2, The control means, in the first pressurization control, increases the pressure to a first pressure greater than the performance requirement pressure, A battery control system that sets the first pressure higher the larger the total value of the remaining discharge capacity.

4. In the battery control system according to claim 3, The control means is a battery control system that sets the first pressure higher the greater the reduction in the thickness of the battery module due to the balancing.

5. In the battery control system according to claim 2, The discharge means is a battery control system that initiates the balancing before the first pressurization control is completed.

6. In the battery control system according to claim 5, The battery module, due to the balancing, shrinks in the shrinkage direction along the stacking direction as the battery cells discharge. The pressure applying means moves along the contraction direction in the first pressurization control, A battery control system in which the amount of movement of the pressure application means in the first pressurization control is greater than or equal to the amount of contraction of the battery module due to the balancing.

7. In the battery control system according to claim 1, The battery control system further includes a determination means for determining whether or not balancing is necessary. The control means is a battery control system that, when it is determined that balancing is not necessary, completes a second pressurization control that increases the pressure to a predetermined pressure or higher to reduce the electrical resistance of the battery cell before the battery module starts charging and discharging to operate the vehicle's control system.

8. A battery control method for controlling a battery module comprising a plurality of stacked battery cells, each having a solid electrolyte and a lithium-containing negative electrode, The remaining discharge capacity of each of the aforementioned battery cells is calculated, By discharging the aforementioned battery cells, the remaining discharge capacity between the battery cells is balanced. A battery control method comprising increasing the pressure applied to the battery module by pressing the battery module along the stacking direction of the battery cells using a pressure application means before the balancing is initiated, up to a predetermined pressure or higher.

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