JP6777588B2 - Battery control device and battery system - Google Patents

Description

The present invention relates to a battery control device for controlling an assembled battery included in a hybrid vehicle and a battery system mounted on the hybrid vehicle.

The hybrid vehicle includes an assembled battery composed of a plurality of cell cells as a driving battery. In an assembled battery, it is inevitable that the open circuit voltage of each cell will vary, and if charge / discharge control is performed collectively for the assembled battery in a state where such variation is large, overcharging or overdischarging will occur in the cell. It will be easier. Therefore, conventionally, a system has been proposed in which the open circuit voltage of each cell is adjusted by detecting the open circuit voltage of each cell and charging or discharging the cell so that the variation becomes small (for example). , Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-246646

By the way, when a current is flowing through the assembled battery, that is, when the assembled battery and the inverter, motor generator, etc. connected to the assembled battery are energized, a polarization voltage having a different magnitude is generated for each cell. It is difficult to accurately detect the open circuit voltage of each cell and its variation. Therefore, it is possible to monitor the open circuit voltage of each cell and adjust it so as to approach the target value only when the assembled battery is in a non-energized state, such as when the key is off in a vehicle. As described above, in the above adjustment mode, there is a limit to the period during which the open circuit voltage can be adjusted, so that there is a limit to reducing the variation in the open circuit voltage of the cell.
An object of the present invention is to provide a battery control device and a battery system capable of suppressing variations in open circuit voltage in the batteries constituting the assembled battery.

The battery control device for solving the above problems is a control device for an assembled battery, which is a secondary battery mounted on a hybrid vehicle, and the assembled battery is composed of a plurality of battery blocks each including one or more single batteries. Each of the determination unit for determining whether the assembled battery is in the non-energized state or the energized state, and the battery block detected when the assembled battery is determined to be in the non-energized state. The charge capacity of each battery block is obtained based on the reference voltage value which is the magnitude of the voltage of the above, and the minimum charge capacity of the charge capacities of the plurality of battery blocks and the charge capacity of each battery block are obtained. A discharge process for discharging each battery block is performed through a target determination unit that determines a target discharge amount of each battery block according to the difference between the above and a discharge circuit provided for each battery block with the target discharge amount as a target. The period in which the discharge control unit is provided and the discharge control unit performs the discharge process includes a period in which the assembled battery is determined to be in the energized state.

The battery system that solves the above problems is a battery system mounted on a hybrid vehicle, and is a combined battery that is a secondary battery composed of a plurality of battery blocks each containing one or more single batteries, and the battery block. It has a voltage detection circuit for detecting the magnitude of each voltage, a discharge circuit provided for each battery block, and a control device for the assembled battery. The control device has a state in which the assembled battery is de-energized. A determination unit that determines which state is in the energized state, and a reference voltage that is the magnitude of the voltage detected by the voltage detection circuit when the assembled battery is determined to be in the non-energized state. The charge capacity of each battery block is obtained based on the value, and the charge capacity of each battery block is determined according to the difference between the minimum charge capacity of the charge capacities of the plurality of battery blocks and the charge capacity of each battery block. A target determination unit for determining a target discharge amount and a discharge control unit for performing a discharge process for discharging each battery block through the discharge circuit with the target discharge amount as a target are provided, and the discharge control unit performs the discharge process. The period for performing the above includes a period in which the assembled battery is determined to be in the energized state.

According to the above configuration, the battery blocks are discharged according to the target discharge amount set based on the charge capacity based on the reference voltage value, so that the reference voltage value of each battery block is adjusted to the minimum reference voltage value. Can be lowered. Since the discharge process is also performed during the energized state, it is possible to secure a longer period during which the discharge process is performed as compared with the mode in which the discharge process is performed only during the non-energized state. Therefore, it is possible to suppress the variation of the reference voltage value in the plurality of battery blocks, that is, the variation of the open circuit voltage of the unit cells constituting the assembled battery.

In the above configuration, when the magnitude of the charge / discharge current of the assembled battery is equal to or less than a predetermined threshold value, the determining unit determines that the assembled battery is in the non-energized state, and the target determining unit determines that the assembled battery is in the non-energized state. As the reference voltage value, it is preferable to use the voltage value detected when the amount of change in the voltage of the assembled battery or the battery block in a unit time is equal to or less than a predetermined threshold value.

According to the above configuration, since the voltage value when the voltage is stable in the non-energized state is used as the reference voltage value, the accuracy of detecting the reference voltage value as the magnitude of the voltage corresponding to the open circuit voltage of the battery block is improved. As a result, it is possible to accurately set the target discharge amount.

In the above configuration, the target determination unit updates the target discharge amount each time the determination by the determination unit switches from the energized state to the non-energized state, and the discharge control unit updates the updated target discharge amount. It is preferable to carry out the discharge treatment using.
According to the above configuration, it is possible to set a target discharge amount that quickly responds to a change in the open circuit voltage of the battery block.

In the above configuration, the discharge control unit discharges the battery block with an integrated value of current values calculated based on the voltage value detected for each battery block and the resistance value of the resistance element included in the discharge circuit. Calculate as a quantity.

According to the above configuration, the circuit for detecting the magnitude of the voltage for each battery block is used not only for detecting the reference voltage value but also for calculating the discharge amount. Therefore, the circuit configuration for realizing the above-mentioned control of the assembled battery by the battery control device becomes simple.

The figure which shows the electrical composition of one Embodiment of a battery system. The figure which shows the relationship between the current flowing through a battery and the open circuit voltage of a cell. A flowchart showing the procedure of the goal setting process. The figure which shows the transition of the voltage of a cell when the battery becomes de-energized. The figure which shows the relationship between the open circuit voltage of a cell and the charge capacity. A flowchart showing a procedure of electric discharge processing. A flowchart showing the procedure of the start determination process. The figure which shows typically the relationship between the transition of the charge capacity difference between battery blocks, and the discharge period.

An embodiment of the battery control device and the battery system will be described with reference to FIGS. 1 to 8. The battery control device of the present embodiment is a device for controlling a battery for driving a hybrid vehicle, and the battery system is a system mounted on the hybrid vehicle.

As shown in FIG. 1, the battery system 10 includes a battery 20 including a plurality of battery blocks 21 and a battery management unit 30 including a battery ECU 31 as a battery control device.

Each of the plurality of battery blocks 21 includes one or more predetermined number of cells, and the plurality of battery blocks 21 are connected in series. When the battery block 21 includes a plurality of cells, these cells are connected in series. That is, the battery 20 is an assembled battery composed of a plurality of single batteries connected in series. A cell is a battery composed of one cell, for example, a lithium ion secondary battery.

The battery 20 is connected to a motor generator (hereinafter referred to as M / G) 50 via an inverter 40. The electric power stored in the battery 20 is supplied to the M / G 50 via the inverter 40, so that the M / G 50 functions as a motor. The rotation of the M / G 50 is transmitted to the drive wheels of the hybrid vehicle via a transmission or the like. Further, the M / G 50 functions as a generator that generates electricity by utilizing the rotation transmitted from the drive wheels, for example, when the accelerator is off, and the electric power generated by the M / G 50 is stored in the battery 20 via the inverter 40. ..

The hybrid vehicle is equipped with an engine together with the M / G 50, and runs by operating at least one of the M / G 50 and the engine as a power source depending on the traveling situation.

The battery management unit 30 includes a discharge circuit C1 for discharging a single battery for each battery block 21 and a voltage detection circuit C2 for detecting a voltage value Vc which is the magnitude of the voltage for each battery block 21. Further, the battery management unit 30 includes a current detection circuit C3 that detects the charge / discharge current of the battery 20, that is, the current value Is, which is the magnitude of the current that flows into or flows out of the battery 20.

The discharge circuit C1 is provided for each battery block 21, and includes, for example, a resistance element having a predetermined resistance value R as a load. The discharge circuit C1 is configured to be able to switch between connection and non-connection between the unit battery constituting the battery block 21 and the load by opening and closing the switch, for example. The connection and disconnection between the cell and the load in the discharge circuit C1 are switched based on the signal input from the battery ECU 31 to the discharge circuit C1.

The voltage detection circuit C2 is provided for each battery block 21 and is configured to be capable of detecting a voltage value Vc which is the magnitude of the voltage between both terminals of the battery block 21. The current detection circuit C3 is configured to be able to detect, for example, the current value Is, which is the magnitude of the current flowing between the inverter 40 and the battery 20. The voltage value Vc detected by the voltage detection circuit C2 and the current value Is detected by the current detection circuit C3 are input to the battery ECU 31 and used for various processes.

The battery ECU 31 is mainly composed of a microcomputer including a CPU, ROM, RAM, and the like, and includes a determination unit 32, a target determination unit 33, a discharge control unit 34, and a storage unit 35.

The determination unit 32 acquires the current value Is detected by the current detection circuit C3, and determines whether the battery 20 is in the non-energized state or the energized state based on the acquired current value Is.

The target determination unit 33 acquires the voltage value Vc of each battery block 21 detected by the voltage detection circuit C2 when it is determined that the battery 20 is in a non-energized state as a reference voltage value Vco, and the acquired reference voltage value. Based on Vco, the charge capacity Sc of each battery block 21 is obtained. Then, the target determination unit 33 determines the target discharge amount Qc for each battery block 21 based on the difference in the charge capacity Sc of each battery block 21.

The discharge control unit 34 controls the discharge circuit C1 for each battery block 21 to discharge until the discharge amount of each battery block 21 through the discharge circuit C1 reaches the target discharge amount Qc.
The storage unit 35 stores data necessary for processing of the determination unit 32, the target determination unit 33, and the discharge control unit 34.

Prior to the operation of the battery system 10, the relationship between the charge / discharge current of the battery 20 and the voltage of the cell constituting the battery 20 will be described with reference to FIG.
FIG. 2 is a graph with the horizontal axis as the time axis, the upper graph shows an example of changes in the magnitudes of the terminal voltages V1 and V2 of each separate cell, and the lower graph shows the battery 20. An example of the transition of the current I, which is the charge / discharge current, is shown. As shown in FIG. 2, when the charge / discharge current does not flow through the battery 20, that is, during the period T1 when the current I is 0A, the terminal voltages V1 and V2 of the cell cells correspond to the open circuit voltages Vo1 and Vo2. Stable with.

On the other hand, during the period T2 in which the charge / discharge current is flowing through the battery 20, the terminal voltages V1 and V2 of the single battery show different values from the open circuit voltages Vo1 and Vo2 due to the generation of the polarization voltage. Then, the terminal voltage V1 and the terminal voltage V2 fluctuate in different modes due to the magnitude of the polarization voltage, the temperature of the cell, and the like being different for each cell. That is, a cell having a larger open circuit voltage does not always have a larger terminal voltage, and the difference in terminal voltage in each cell does not always match the difference in open circuit voltage.

Therefore, as the voltage value of each battery block 21, the reference voltage value Vco corresponding to the magnitude of the open circuit voltage of the battery block 21, that is, the voltage value of the sum of the open circuit voltages of the cells constituting the battery block 21 is used. In order to obtain the voltage value Vc, the voltage value Vc may be detected when the current value Is is small enough to be regarded as 0A. Since there is a correlation between the open circuit voltage of the cell and the charge capacity, the charge capacity Sc of the battery block 21 can be obtained based on the reference voltage value Vco.

The operation of the battery system 10 will be described with reference to FIGS. 3 to 7.
FIG. 3 shows a procedure of the target setting process performed by the target determination unit 33 of the battery ECU 31. The goal setting process is performed every time the start condition is satisfied. The start condition includes that the determination unit 32 determines that the battery 20 is in a non-energized state, that is, the absolute value of the current value Is is equal to or less than a threshold value near 0.

In the process of step S10, it is determined whether or not the voltage change rate, which is the amount of change in the voltage value Vc of each battery block 21 in a unit time, is equal to or less than the voltage determination value, which is a predetermined threshold value. When the voltage change rate is larger than the voltage determination value (step S10: NO), the process of step S10 is repeated, and the voltage value Vc is monitored until the voltage change rate becomes equal to or less than the voltage determination value. When the voltage change rate becomes equal to or less than the voltage determination value (step S10: YES), the voltage value Vc of each battery block 21 is stored as the reference voltage value Vco as the process of step S11.

As shown in FIG. 4, it takes a certain amount of time after the charge / discharge current is stopped to relax the polarization voltage generated when the charge / discharge current is flowing through the battery 20. When the relaxation time t elapses, the magnitude of the voltage indicated by the cell becomes stable at a magnitude corresponding to the open circuit voltage. Therefore, when the current value Is is equal to or less than the current determination value and the voltage change rate is equal to or less than the voltage determination value, the voltage value Vc of the battery block 21 is a reference voltage value that can be regarded as the open circuit voltage of the battery block 21. Vco can be detected.

The timing of storing the reference voltage value Vco may be determined for each battery block 21 based on the voltage change rate for each battery block 21, or the voltage change rate for all battery blocks 21 is equal to or less than the voltage determination value. It may be determined uniformly for all the battery blocks 21 on the condition that Alternatively, the timing of storing the reference voltage value Vco may be uniformly determined for all the battery blocks 21 based on the rate of change in the voltage of the entire battery 20 instead of the rate of change in the voltage for each battery block 21. Good.

When the reference voltage value Vco of each battery block 21 is stored in the target setting process of FIG. 3, the charge capacity Sc is obtained for each battery block 21 based on the reference voltage value Vco as the process of step S12.

FIG. 5 shows an example of the relationship between the open circuit voltage [V] and the charge capacity [Ah] in a single battery. The charge capacity is an amount expressed by the product of the current and the time, which is how much current the battery can supply and how long, and the charge capacity increases as the open circuit voltage increases. The storage unit 35 of the battery ECU 31 stores a map that defines the relationship between the reference voltage value Vco and the charge capacity Sc based on the relationship between the open circuit voltage and the charge capacity of the cell, and is determined in this map and step S10. The charge capacity Sc for each battery block 21 is obtained based on the reference voltage value Vco. In addition, instead of the map, the charge capacity Sc may be obtained by using a calculation formula.

When the charge capacity Sc of each battery block 21 is obtained in the target setting process of FIG. 3, the target discharge amount Qc for each battery block 21 is determined as the process of step S13. Specifically, the target determination unit 33 selects the minimum charge capacity Scmin from the charge capacity Sc of each battery block 21, and subtracts the minimum charge capacity Scmin from the charge capacity Sc of each battery block 21. , The target discharge amount Qc [Ah] of each battery block 21 is determined. That is, the target discharge amount Qc of the battery block 21 having the minimum charge capacity Scmin is 0 Ah, and the battery blocks 21 other than the battery block 21 having the minimum charge capacity Scmin have the charge capacity Sc of the target battery block 21. The amount of electricity that is different from the minimum charge capacity Scmin is the target discharge amount Qc [Ah] of the target battery block 21.
By such a target setting process, the target discharge amount Qc of each battery block 21 is set.

FIG. 6 shows the procedure of the electric discharge process. The discharge process is performed by the discharge control unit 34 for each of the battery blocks 21 when the target discharge amount Qc is set by the target setting process.

As the process of step S20, it is determined whether or not the target discharge amount Qc of the target battery block 21 is a value different from 0Ah. When the target discharge amount Qc is 0 Ah (step S20: NO), the discharge control unit 34 ends the process without performing the subsequent process.

When the target discharge amount Qc other than 0Ah is set (step S20: YES), the discharge control unit 34 starts discharging the target battery block 21 as the process of step S21. That is, the discharge control unit 34 connects the load included in the discharge circuit C1 to the battery block 21 by outputting a signal for closing the switch of the discharge circuit C1 corresponding to the target battery block 21 to the discharge circuit C1. It is preferable that the discharge is started all at once with respect to the battery block 21 in which the target discharge amount Qc other than 0 Ah is set.

Subsequently, as the process of step S22, it is determined whether or not the amount of electricity discharged by the battery block 21 through the discharge circuit C1 after the target discharge amount Qc is set reaches the target discharge amount Qc. The discharge amount of the battery block 21 is calculated as an integrated value of the current for a unit time flowing through the load of the discharge circuit C1. The magnitude of the current flowing through the load of the discharge circuit C1 is calculated based on the voltage value Vc detected by the voltage detection circuit C2 and the resistance value R of the resistance element included in the discharge circuit C1.

When the discharge amount of the battery block 21 does not reach the target discharge amount Qc (step S22: NO), the discharge is continued and the process of step S22 is repeated. When the discharge amount of the battery block 21 reaches the target discharge amount Qc (step S22: YES), as the process of step S23, the discharge control unit 34 stops the discharge of the target battery block 21 and ends the process. That is, the discharge control unit 34 outputs a signal for opening the switch of the discharge circuit C1 corresponding to the target battery block 21 to the discharge circuit C1 to cut off the continuity between the load included in the discharge circuit C1 and the battery block 21.

When the amount of electricity of the target discharge amount Qc is discharged, the open circuit voltage of the single battery constituting the battery block 21 is lowered, and the variation of the reference voltage value Vco among the battery blocks 21 is reduced.

FIG. 7 shows a procedure of the start determination process for determining whether or not the start condition of the target setting process is satisfied. For example, when the ignition switch is turned on, the start determination process is repeatedly performed by the determination unit 32.

First, as the process of step S30, it is determined whether or not the battery 20 is in a non-energized state, that is, whether or not the current value Is is equal to or less than the above-mentioned current determination value. When it is determined that the battery 20 is not in the non-energized state, that is, when the current value Is is larger than the current determination value (step S30: NO), the process of step S30 is repeated. It should be noted that the determination that the battery 20 is not in the non-energized state is the same as the determination that the battery 20 is in the energized state. When it is determined that the battery 20 is in the non-energized state, for example, when the vehicle is stopped or the engine is running, and when it is determined that the battery 20 is in the energized state, for example, when the motor is running or when the engine is regenerating. Is.

When it is determined in the process of step S30 that the battery 20 is in a non-energized state, that is, when the current value Is is equal to or less than the current determination value (step S30: YES), the process of step S31 is started. It is determined that the condition is satisfied. As a result, the target setting process is started, and the discharge process is started following the target setting process.

Subsequently, as the process of step S32, it is determined whether or not the battery 20 is in the energized state, that is, whether or not the current value Is is larger than the current determination value. When it is determined that the battery 20 is not energized (step S32: NO), that is, while the non-energized state continues from the time when the affirmative determination is made in step S30, the process of step S32 is repeated.
On the other hand, when it is determined that the battery 20 is in the energized state (step S32: YES), the determination unit 32 temporarily ends a series of processes.

By repeating the above-mentioned start determination process, when the battery 20 is energized and then de-energized again, it is determined that the start condition is satisfied, and the target setting process is started. Therefore, the target setting process is performed every time it is determined that the battery 20 is switched from the energized state to the non-energized state, and the target discharge amount Qc is updated by setting a new target discharge amount Qc. Then, following the target setting process, the discharge process is performed using the updated target discharge amount Qc.

The operation of the present embodiment will be described with reference to FIG. In the present embodiment, the discharge process is performed regardless of the current value Is, subject to the setting of the target discharge amount Qc. That is, the discharge process is continued not only when the non-energized state of the battery 20 continues after the target discharge amount Qc is set, but also when the battery 20 is energized due to the start of motor running or the like. The target discharge amount Qc is set based on the charge capacity Sc based on the reference voltage value Vco in the non-energized state, and the charge capacity Sc is brought closer to the minimum charge capacity Scmin by discharging, which corresponds to the open circuit voltage of each battery block 21. The reference voltage value Vco can be lowered to match the minimum reference voltage value Vco. In such a form, even when the battery 20 is energized, the discharge process can be performed to reduce the variation in the reference voltage value Vco.

FIG. 8 shows an example of the transition of the difference in charge capacity Sc between arbitrary battery blocks 21 among the plurality of battery blocks 21, and when the one-dot chain line L1 is not discharged, the two-dot chain line L2 is in a non-energized state. When the discharge treatment is performed only on the period TN, the solid line L3 indicates the case where the discharge treatment is performed not only on the non-energized period TN but also on the energized period TE. The difference in charge capacity Sc gradually increases mainly during the period in which the battery 20 is used and the discharge process is not performed. Since the discharge treatment is performed, the difference in charge capacity Sc becomes small during the period during which the discharge treatment is performed. However, when the target setting process and the discharge process are performed only in the non-energized state, the difference in charge capacity Sc expanded during the period when the discharge is not performed is not completely reduced depending on the discharge period Ta, and is a long period of time. The difference in charge capacity Sc may increase between the two. On the other hand, it is possible to secure a long discharge period Tb by performing the discharge process even when the power is on, and the difference in charge capacity Sc generated during the period when the discharge is not performed is the discharge period. It is easily eliminated during Tb, and it is possible to suppress an increase in the difference in charge capacity Sc. Therefore, the variation of the reference voltage value Vco can be made smaller.

As described above, according to the battery control device and the battery system of the present embodiment, the following effects can be obtained.
(1) The target discharge amount Qc of each battery block 21 is set with reference to the charge capacity Sc based on the reference voltage value Vco in the non-energized state, and discharge is performed. Therefore, the reference voltage value Vco of each battery block 21 can be lowered so as to match the minimum reference voltage value Vco without the need to monitor the open circuit voltage. Since the discharge process is also performed during the period when the battery 20 is determined to be in the energized state, the period during which the discharge process is performed can be secured for a long time. Therefore, it is possible to reduce the variation of the reference voltage value Vco in the plurality of battery blocks 21, that is, the variation of the open circuit voltage of the unit cells constituting the battery. In addition, it is easy to maintain a state in which the variation in the open circuit voltage between the cells is small, so that over-discharging and over-charging of the cells can be suppressed.

(2) As the reference voltage value Vco, a voltage value detected when the amount of change in the voltage of the battery 20 or the battery block 21 in a unit time is equal to or less than a predetermined threshold value in a non-energized state is used. Therefore, since the voltage value when the voltage is stable in the non-energized state is used as the reference voltage value Vco, the accuracy of detecting the reference voltage value Vco as the magnitude of the voltage corresponding to the open circuit voltage is improved, and eventually the target discharge. The amount Qc can be set accurately.

(3) Every time the battery 20 is switched from the energized state to the non-energized state, the target discharge amount Qc is updated, and the discharge process is performed according to the updated target discharge amount Qc. Therefore, it is possible to set the target discharge amount Qc that quickly responds to the change in the open circuit voltage of the cell constituting the battery block 21.

(4) The discharge control unit 34 calculates the integrated value of the current values based on the voltage value Vc and the resistance value R as the discharge amount for each battery block 21. That is, the voltage detection circuit C2 for each battery block 21 is used not only for detecting the reference voltage value Vco but also for calculating the discharge amount. Therefore, the circuit configuration for realizing the above control of the battery 20 is simplified.

The above embodiment can be modified and implemented as follows.
The reference voltage value Vco may be the voltage value Vc when a predetermined relaxation time t has elapsed after the determination that the non-energized state has been established, regardless of the voltage change rate.

-The start condition of the target setting process is not limited to the condition shown in the above embodiment. That is, the target discharge amount Qc does not have to be updated every time the battery 20 is switched from the energized state to the non-energized state. For example, when a predetermined time has elapsed since the end of the previous discharge process, the non-energized state may be determined and the target setting process may be performed to update the target discharge amount Qc.

The determination unit 32 may, for example, acquire information on the driving state of the hybrid vehicle and determine whether the battery 20 is in the non-energized state or the energized state based on the acquired information.
-The assembled battery controlled by the battery control device is not limited to the lithium ion secondary battery. Any secondary battery that can cause variations in the open circuit voltage of the cell can be controlled by the battery control device.

10 ... Battery system, 20 ... Battery, 21 ... Battery block, 30 ... Battery management unit, 31 ... Battery ECU, 32 ... Judgment unit, 33 ... Target determination unit, 34 ... Discharge control unit, 35 ... Storage unit, 40 ... Inverter , 50 ... motor generator, C1 ... discharge circuit, C2 ... voltage detection circuit, C3 ... current detection circuit, Sc ... charge capacity, Qc ... target discharge amount, Vco ... reference voltage value.

Claims (5)

It is a control device for a built-in battery, which is a secondary battery installed in a hybrid vehicle.
The assembled battery is composed of a plurality of battery blocks, each containing one or more cell cells.
A determination unit for determining whether the assembled battery is in a non-energized state or an energized state,
Based on the reference voltage value, which is the magnitude of the voltage for each battery block detected when the assembled battery is determined to be in the non-energized state, the charge capacity for each battery block is obtained, and the plurality of batteries are obtained. A target determination unit that determines the target discharge amount of each battery block according to the difference between the minimum charge capacity of the charge capacity of the battery block and the charge capacity of each battery block.
A discharge control unit that performs a discharge process for discharging each battery block through a discharge circuit provided for each battery block with the target discharge amount as a target is provided.
A battery control device in which the period during which the discharge control unit performs the discharge process includes a period during which the assembled battery is determined to be in the energized state. When the magnitude of the charge / discharge current of the assembled battery is equal to or less than a predetermined threshold value, the determination unit determines that the assembled battery is in the non-energized state.
The battery according to claim 1, wherein the target determination unit uses a voltage value detected when the amount of change in the voltage of the assembled battery or the battery block in a unit time is equal to or less than a predetermined threshold value as the reference voltage value. Control device. The target determination unit updates the target discharge amount each time the determination by the determination unit switches from the energized state to the non-energized state.
The battery control device according to claim 1 or 2, wherein the discharge control unit performs the discharge process using the updated target discharge amount. The discharge control unit calculates the integrated value of the current value calculated based on the voltage value detected for each battery block and the resistance value of the resistance element included in the discharge circuit as the discharge amount of the battery block. The battery control device according to any one of claims 1 to 3. A battery system installed in hybrid vehicles
A rechargeable battery, which is a secondary battery composed of a plurality of battery blocks each containing one or more cell cells,
A voltage detection circuit that detects the magnitude of the voltage for each battery block,
The discharge circuit provided for each battery block and
It has the control device of the assembled battery and
The control device is
A determination unit for determining whether the assembled battery is in a non-energized state or an energized state,
Based on the reference voltage value, which is the magnitude of the voltage detected by the voltage detection circuit when the assembled battery is determined to be in the non-energized state, the charge capacity for each battery block is obtained, and the plurality of batteries are obtained. A target determination unit that determines the target discharge amount of each battery block according to the difference between the minimum charge capacity of the charge capacity of the battery block and the charge capacity of each battery block.
A discharge control unit that performs a discharge process for discharging each battery block through the discharge circuit with the target discharge amount as a target is provided.
A battery system in which the period during which the discharge control unit performs the discharge process includes a period during which the assembled battery is determined to be in the energized state.

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