JP2015119578A - Current abnormality detection device, battery pack, current abnormality detection method, and its program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect abnormality of a regenerative current in an active cell balancing circuit according to an operating mode.SOLUTION: An abnormal current detection device includes: current detection means (15, 16) for detecting a regenerative current in an active cell balancing circuit (for example, 11, 12, 13); and abnormality determination means 10 changing a current range for determining whether the regenerative current is normal according to an operating mode of the active cell balancing circuit, and determining whether the regenerative current detected by the current detection means falls within the normal range. Thus, the abnormality of the regenerative current can be detected according to the operating mode of the active cell balancing circuit, thereby improving the reliability of the active cell balancing circuit and a battery pack including the active cell balancing circuit.

Description

  The present invention relates to a current abnormality detection device that detects a current abnormality including a regenerative current in an active cell balance circuit, a battery pack including the current abnormality detection device, a current abnormality detection method, and a program thereof.

  Along with the battery module, an active cell balance circuit and a battery monitoring unit are mounted on the battery pack. A large regenerative current is passed by the active cell balance circuit to move the charge between cells, and the voltage between cells is reduced in a short time. Are balanced (balanced). In order to cope with a case where an overcurrent flows due to an abnormality of the active cell balance circuit, a circuit for stopping the active cell balance circuit by an abnormality detection circuit and a detected signal is required. For example, when the output of the active cell balance circuit is short-circuited with a resistance of several mΩ to several Ω, the regenerative current (current that flows during cell balance operation) flows ± 10 A, so the regenerative current abnormality range becomes ± 5 A or more. If set, it can be easily detected.

  For example, Patent Documents 1 and 2 below describe that an abnormal current of an active cell balance circuit is detected and an overcurrent current path is interrupted when the abnormal current is detected. Patent Document 1 describes a cell balance device and a battery system that can detect an overcurrent and turn off the switch circuit when an overcurrent flows through the switch circuit.

  Further, in Patent Document 2, in the active cell balance circuit, an overcurrent to the first and second switch elements connected in parallel to each of the cells connected in series is detected. The control means for turning off the second switch element is described.

JP 2013-46433 A JP 2013-55837 A

  However, in the conventional current abnormality detection device and current abnormality detection method, when the output of the active cell balance circuit is short-circuited by a resistance of several tens of Ω, if the regenerative current flows below ± 5 A, the regenerative current abnormality range is set to ± If it is set to 5A or more, no abnormality is detected. That is, since the regenerative current fluctuates according to the equalization operation mode of the active cell balance circuit, the regenerative current abnormality cannot be detected with high accuracy.

  Accordingly, an object of the present invention is to detect an abnormality of a regenerative current of an active cell balance circuit with high accuracy according to an equalization operation mode.

  The abnormal current detection device according to the first aspect of the present invention determines whether or not the regenerative current is normal according to the current detection means for detecting the regenerative current in the active cell balance circuit and the operation mode of the active cell balance circuit. And an abnormality determination unit that changes a current range and determines whether or not the regenerative current detected by the current detection unit is in a normal range.

A battery pack according to a second aspect of the invention includes the abnormal current detection device.
According to a third aspect of the present invention, there is provided an abnormal current detection method comprising: a first process for detecting a regenerative current in an active cell balance circuit; and a range of a current for determining whether the regenerative current is normal according to an operation mode of the active cell balance circuit. And a third process for detecting an abnormal current depending on whether or not the regenerative current is within the range of the determination current changed in the second process.

  According to a fourth aspect of the invention, there is provided a cell voltage difference calculation process for calculating a cell voltage difference from each cell voltage acquired from an active cell balance circuit and a cell voltage adjacent to each cell voltage, and active according to the cell voltage difference. An operation mode setting process for setting an operation mode of the cell balance circuit, a normal range setting process for setting a normal range of the regenerative current according to the set operation mode, and a normal state in which the regenerative current in the active cell balance circuit is set A regenerative current determination process for determining whether or not the current value is within the range is executed by a computer.

  According to the present invention, the abnormality of the regenerative current can be detected with high accuracy according to the operation mode of the active cell balance circuit, so that the reliability of the battery pack including the active cell balance circuit and the current abnormality detection device is improved. Can be made.

1 is a block diagram showing an outline of a battery pack 1 including a current abnormality detection device according to Embodiment 1 of the present invention. Circuit example of current abnormality detection device of embodiment 1 of the present invention The figure explaining the detection range and non-detection range of the current abnormality in the conventional current abnormality detection device The figure explaining the detection range and non-detection range of a current abnormality in the current abnormality detection device according to the first embodiment of the present invention. The flowchart which shows the electric current abnormality detection process of Embodiment 1 of this invention. The flowchart which shows the equalization process of CCV mode in FIG. The flowchart which shows the equalization processing of 50% DUTY mode in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Configuration of the first embodiment)
FIG. 1 is a block diagram showing an outline of a battery pack 1 including a current abnormality detection device according to Embodiment 1 of the present invention.

  The battery pack 1 of FIG. 1 includes a battery module 2 configured by connecting a plurality of cells in series, and a cell as an active cell balance circuit that equalizes cell voltage imbalance among the plurality of cells constituting the battery module. A balance unit 3, a battery monitoring electronic control unit (Electronic Control Unite, hereinafter referred to as “battery monitoring ECU”) 4 that monitors cells in the battery module 2, and a battery control electronic control unit (Electronic Control Unit) that controls the entire battery pack Unite (hereinafter referred to as “battery control ECU”) 5 is connected to each other via a communication line.

FIG. 2 is a circuit example of the current abnormality detection device according to the first embodiment of the present invention.
The current abnormality detection device included in the cell balance unit 3 includes a microcomputer (hereinafter referred to as “microcomputer”) 10 that controls the entire device and pulse width modulation (hereinafter referred to as “pulse width modulation”) according to the operation mode of the active cell balance circuit set by the microcomputer 10. A converter control IC (Integrated Circuit) 11 that outputs a “PWM” signal, and a field effect transistor (hereinafter referred to as “FET”) that controls ON / OFF between the drain and the source when the PWM signal is input to the gate. 12, 13, an inductance 14 for temporarily storing electric power for equalization, a current detection resistor 15, a current monitor circuit 16 as a conversion means, and an average current setting circuit 17. The average current setting circuit 17 outputs an average current setting signal that gives an average value of the regenerative current to the converter control IC 11 when the operation mode setting signal given from the cell voltage difference determination unit 22 is in the CCV mode.

  Here, the operation mode set by the microcomputer 10 includes a constant current charge / discharge (CCV) mode in which the current is equalized with a constant current, and a pulse width is modulated in accordance with an adjacent cell voltage difference when the cell voltage difference is reduced. There is a 50% DUTY mode in which charging / discharging is performed with a current corresponding to the pulse width.

The positive terminal of the cell Cen _{+ 1} is connected to the positive terminal of the FET 12, for example, the drain. Moreover, the negative terminal of the negative terminal and FET13 cell Ce _n, for example, the source is connected.

The cell balance unit 3 in FIG. 1 includes the converter control IC 11, FETs 12 and 13, and an inductance 14 in FIG. 2. 2, if the cell voltage _{V n + 1} of the cell _{Ce n + 1} is greater than the cell voltage _{V n} of the cell Ce _n is a regenerative current flows from the cell _{Ce n + 1} to the arrows shown by the two-dot chain line toward the cell Ce _n . On the other hand, in FIG. 2, the cell _{Ce n + 1} If the cell voltage _{V n + 1} is smaller than the cell voltage _{V n} of the cell Ce _n is regenerative current flows from the cell Ce _n to cell _{Ce n + 1} to the arrows shown by a chain line Flows.

Converter control IC 11 outputs a PWM signal having a duty ratio corresponding to the operation mode given from microcomputer 10.
Microcomputer 10, the battery monitor ECU4, CAN (Controller Area Network) cell _Ce 1 of the communication and ^I 2 C (I Square Sea) within the battery pack 1 by communication or the like, · · _·, Ce n, each _{Ce n + 1} Cell voltages V ₁ ,..., V _n , V _{n + 1} are input via a communication connector, and a cell voltage input unit 21 that outputs all cell voltages is input. The mode setting signal corresponding to the cell voltage difference obtained using the input voltage is output to the converter control IC 11 and the average current setting circuit 17, and the operation start / stop signal is output to the converter control IC 11 according to a predetermined condition. Cell voltage difference determination unit 22, normal current range setting unit 23 for setting a normal current range of regenerative current Ik according to the operation mode, and whether regenerative current Ik is in a normal current range Or to determine the, if not normal current range, and a regenerative current abnormality detector 24 outputs a stop signal to the converter control IC 11, the. The cell voltage input unit 21, the cell voltage difference determination unit 22, the normal current range setting unit 23, and the regenerative current abnormality detection unit 24 in the microcomputer 10 constitute an abnormality determination unit.

  When an operation start / stop signal instructing “operation start” is input from cell voltage difference determination unit 22, converter control IC 11 receives an operation mode setting signal and average current setting circuit 17 provided from cell voltage difference determination unit 22. The PWM signal according to the given average current setting signal is output. When an operation start / stop signal instructing “stop operation” is input from the cell voltage difference determination unit 22, the converter control IC 11 stops the operation. Furthermore, also when the regenerative current abnormality detection unit 24 detects a regenerative current abnormality and outputs a stop signal, the converter control IC 11 stops its operation.

The functional blocks in the microcomputer 10 in FIG. 2 may be configured by hard logic, or may be realized by reading into the microcomputer 10 a program stored in an external or internal storage device (not shown).
(Operation of the first embodiment)
The operation of the first embodiment of the present invention will be described separately for (I) the conventional abnormal current detection method, (II) the abnormal current detection method of the present embodiment, and (III) details of the abnormal current detection processing. .
(I) Conventional Abnormal Current Detection Method FIGS. 3A and 3B are diagrams illustrating a current abnormality detection range and a non-detection range in a conventional current abnormality detection device. FIG. It is a figure which shows the regenerative voltage Vk (V) with respect to the regenerative current detection voltage Vs (mV), and a regenerative current abnormal range, FIG.3 (b) is a figure which shows the regenerative current waveform with respect to each operation mode.

First, the operation of the conventional current abnormality detection device will be described with reference to FIGS.
In FIG. 3A, the regenerative current abnormality range is set such that the regenerative voltage is greater than + 4.1V or less than + 0.5V. In the conventional abnormal current detection device, the range where the regenerative current is larger than the maximum value in all the operation modes and the range where the regenerative current is less than the minimum value in all the operation modes are defined as the regenerative current abnormality range. The regenerative voltage Vk is obtained by converting the voltage difference Vs across the resistor 15 in FIG. That is, the current monitor circuit 16 reads the regenerative current as a regenerative current detection voltage Vs (a value that reads a current flowing during the cell balance operation as a voltage) Vs, and further converts it into a regenerative voltage Vk.

  The regenerative voltage + 4.1V in FIG. 3 (a) corresponds to the minimum current value −5A of the regenerative current Ik in the CCV mode depicted in the upper part of FIG. 3 (b), and the regenerative current Ik is less than −5A. The corresponding current abnormality detection voltage range corresponds to the regenerative voltage Vk> + 4.1V. Similarly, the regenerative voltage Vk + 0.5V in FIG. 3A corresponds to the maximum current value + 5A of the regenerative current Ik in the CCV mode depicted in the lower part of FIG. 3B, and the regenerative current Ik is from + 5A. The current abnormality detection voltage range corresponding to large corresponds to the regenerative voltage Ik <+ 0.5V.

  In FIG.3 (b), the normal range of the regenerative current Ik in CCV mode is -5A or more and -3A or less, or 3A or more and 5A or less, and the normal range of the regenerative current Ik in 50% DUTY mode is -1A or more and + 1A or less. The normal range of the regenerative current Ik in the sleep mode and the shutdown mode is −0.2 A or more and +0.2 A or less. In cases other than the normal range in each mode, it is an abnormal current range by design. For example, a range that is larger than -3A and smaller than -1A, and a range that is larger than + 1A and smaller than + 3A is an abnormal current range. Could not be detected.

In the conventional abnormal current detection device, for example, the abnormal operation in which the regenerative current in the 50% DUTY mode in which ± 1 A or less is in the normal range is ± 1.5 A cannot be detected. Therefore, the operation deviating from the design range is continued, and there is a possibility that reliability and durability are impaired. Therefore, the abnormal current detection method of the present embodiment described below is adopted.
(II) Abnormal Current Detection Method of the Present Embodiment FIG. 4 is a diagram for explaining the current abnormality detection range and the undetected range in the current abnormality detection device of the first embodiment of the present invention, and FIG. It is a figure which shows the regenerative voltage (V) with respect to the regenerative current detection voltage Vs (mV), and a regenerative current abnormal range, and FIG.4 (b) is a figure which shows the regenerative current waveform with respect to each operation mode.

Next, based on FIG. 4, operation | movement of the electric current abnormality detection apparatus of Embodiment 1 of this invention is demonstrated.
In FIG. 4A, the abnormal range of the regenerative current is set as follows, and the setting of the abnormal range is changed according to each operation mode. Note that the normal range in each operation mode is a range that is not an abnormal range.
CCV mode step-down operation at regenerative voltage obtained by converting regenerative current (cell balance operation to transfer charge from high potential cell to low cell with respect to connection point of adjacent cells)
Regenerative voltage <+ 0.5V, + 1.3V <Regenerative voltage 50% During DUTY mode operation Regenerative voltage <+ 2.1V, + 2.9V <Regenerative voltage CCV mode During boost operation (the potential of the adjacent cell connection point Cell balance operation to move charge from low cell to high cell)
Regenerative voltage <+ 3.3V, + 4.1V <regenerative voltage The regenerative voltages + 0.5V, + 1.3V, + 2.1V, 2.9V, 3.3V, and + 4.1V in FIG. This corresponds to the regenerative currents + 5A, + 3A, + 1A, -1A, -3A, and -5A in b).

  In FIG. 4B, when it is outside the normal current range of the regenerative current in the CCV mode and the 50% DUTY mode, it becomes the current abnormality detection voltage range in FIG. 4A, and the CCV mode (step-down operation or step-up operation) and 50 When the regenerative current in the% DUTY mode falls outside the assumed current range in the design, abnormal current detection can be performed. Thereby, since abnormal operation in the CCV mode and the 50% DUTY mode can be detected at an early stage, the possibility of impairing reliability and durability can be reduced.

The same is true even if the abnormal range of the regenerative current is set not by voltage but by current. For example, in CCV mode step-down operation, regenerative current <+ 3A, + 5A <regenerative current, in 50% DUTY mode, regenerative current <-1A, + 1A <regenerative current, and in CCV step-up operation, regenerative current <-5A, -3A <regenerative The current may be set to the abnormal range of each operation mode. The normal range in each operation mode is a range that is not an abnormal range. In this case, a current sensor using magnetism instead of resistance may be used as the current detection means.
(III) Details of Abnormal Current Detection Processing FIG. 5 is a flowchart showing processing in the current abnormality detection device of Embodiment 1 of the present invention, and FIG. 6 is a flowchart showing CCV mode equalization processing in FIG. Furthermore, FIG. 7 is a flowchart showing the equalization processing in the 50% DUTY mode in FIG.

Finally, the details of the abnormal current detection process will be described with reference to FIGS. 2 and 4 and the flowcharts of FIGS.
In FIG. 5, when the process is started, the process proceeds to step S1, and the microcomputer 10 transmits the cell voltage information V _{n + 1} , V _n ,..., V ₁ from the battery monitoring ECU through CAN communication, I ² C communication, or the like. Acquire and go to step S2. In step S2, it is determined whether or not the adjacent cell voltage difference is 10 mV or less. If the cell voltage difference is not 10 mV or less (No), the process proceeds to step S3, and if the cell voltage difference is 10 mV or less (Yes) ), Go to step S15. When the process proceeds to step S3, the CCV mode equalization process is performed in steps S3 to S14, and the process proceeds to step S15.

  When the process proceeds to step S15, the equalization process in the 50% DUTY mode is performed in steps S15 to S19, the process proceeds to step S20, the cell balance is completed in step S20, and the process ends.

In FIG. 6, when the equalization process in the CCV mode is started, the process proceeds to step S3. In step S3, the microcomputer 10 sets the operation mode of the converter control IC 11 to the CCV mode, and then proceeds to step S4. In step S4, the microcomputer 10 compares adjacent cell voltages V _{n + 1} and V _n to determine whether V _{n + 1} > V _{n, and} if V _{n + 1} > V _{n, that} is, if the positive-side cell voltage is high ( Yes), the process proceeds to step S5. If V _{n + 1} ≦ V _{n, that} is, if the negative electrode side cell is high (No), the process proceeds to step S10.

In step S5, the microcomputer 10 sets the converter control IC11 in the step-down operation (operation of moving the charge from the cell _{Ce n + 1} to the cell Ce _n), the process proceeds to step S6. In step S6, the microcomputer 10 sets the normal current detection range to +3 A or more and +5 A or less (corresponding to +0.5 V or more and +1.3 V or less in the regenerative voltage), and proceeds to step S7. In step S7, when an operation start signal is input from the microcomputer 10, the converter control IC 11 starts the operation and outputs a PWM signal corresponding to a constant current step-down operation. When the PWM signal corresponding to the step-down operation of the constant current from the converter control IC11 is input to the two FETs 12, 13, the direction of Ce _n from cell _{Ce n + 1} in FIG. 2, i.e., the current in the direction of the arrow indicated by the two-dot chain line flow, uniform the cell voltages of the cells _{Ce n + 1} and the cell Ce _n is started, the process proceeds to step S8. In step S8, the microcomputer 10 determines whether or not the regenerative current is within the normal current detection range set in step S6. If it is within the normal range, the microcomputer 10 proceeds to step S9. Exit.

In step S9, whether or not the cell voltage difference _{V n} + 1 -V _n ≦ 10mV is determined, and until the cell voltage difference _{V n + 1 -V n ≦ 10mV} (Yes), the equalization operation in the step-down operation of the constant current is continued When the cell voltage difference V _{n + 1} −V _n ≦ 10 mV is satisfied (Yes), the process proceeds to step S15.

In step S10, the microcomputer 10 sets the converter control IC11 to boost operation (operation of moving the charge from the cell Ce _n to cell _{Ce n + 1),} the process proceeds to step S11. In step S11, the microcomputer 10 sets the normal current detection range to -5A or more and -3A or less (corresponding to + 3.3V or more and + 4.1V or less in the regenerative voltage), and proceeds to step S12. In step S12, upon receiving an operation start signal from the microcomputer 10, the converter control IC 11 starts the operation and outputs a PWM signal corresponding to a constant current boosting operation. When the PWM signal corresponding to the boosting operation of the constant current from the converter control IC11 is input to the two FETs 12, 13, the direction of _{Ce n + 1} from the cell Ce _n in FIG. 2, i.e., arrow dashed line in FIG. 2 current flows in a direction, the equalization of the cell Ce _n and the cell _{Ce n + 1} of the cell voltage is started, the process proceeds to step S13.

  In step S13, the microcomputer 10 determines whether or not the regenerative current is within the normal current detection range set in step S11. If it is within the normal range, the process proceeds to step S14. Exit.

In step S14, whether or not the cell voltage difference _{V n -V} n _{+ 1} ≦ 10mV is determined, and until the cell voltage difference _{V n -V n + 1 ≦ 10mV} (Yes), the equalization operation in the step-down operation of the constant current is continued When the cell voltage difference V _n −V _{n + 1} ≦ 10 mV is satisfied (Yes), the process proceeds to step S15.

  The processes in steps S3 to S14 are CCV mode processes. In the example shown in FIG. 4, the average value of the regenerative current in the CCV mode is, for example, −4 A for the boost operation and +4 A for the step-down operation. When the microcomputer 10 sets the CCV mode for the average current setting circuit 17, the average current setting circuit 17 controls the converter so that the average value of the regenerative current is, for example, -4A in the step-up operation and + 4A in the step-down operation. Control the IC 11.

In FIG. 7, when the equalization process in the 50% DUTY mode is started, the process proceeds to step S15. In step S15, the microcomputer 10 sets the converter control IC 11 to the 50% DUTY mode, and the process proceeds to step S16. In step S16, the normal current detection range is set to -1A or more and + 1A or less (corresponding to + 2.1V or more and + 2.9V or less in the regenerative voltage), and the process proceeds to step S17. In step S17, when an operation start signal is input from the microcomputer 10, the converter control IC 11 starts the operation and outputs a PWM signal corresponding to the 50% DUTY mode. When the PWM signal corresponding from the converter control IC11 to 50% DUTY mode is inputted to the two FETs 12, 13, between the cell Ce _n and the cell _{Ce n + 1} adjacent in Figure 2, high cell than CCV mode precision Ce The equalization of the cell voltages of _n and cell Cen _{+ 1} is started, and the process proceeds to step S18. In step S18, the microcomputer 10 determines whether or not the regenerative current is within the normal current detection range set in step S16. If it is within the normal range, the microcomputer 10 proceeds to step S19. Exit.

In step S19, the microcomputer 10, the cell voltage difference _| V _{n -V} n _{+ 1 |} determines whether ≦ 5 mV or not, the cell voltage difference _| V _{n -V} n _{+ 1 |} and until ≦ 5mV (Yes), 50% DUTY mode When the equalization operation in is continued and the cell voltage difference | V _n −V _{n + 1} | ≦ 5 mV is satisfied (Yes), the process proceeds to step S20. In step S20, the microcomputer 10 completes the cell balance, sets the converter control IC 11 to the sleep mode, and ends the process.

  The processes in steps S15 to S19 are 50% DUTY mode processes. In the example shown in FIG. 4, the upper limit value and the lower limit value of the regenerative current in the 50% DUTY mode are, for example, ± 1A.

In the description the flowchart shown in FIG. 5, in order to facilitate understanding of the invention, the two cells _{Ce n} + 1, Ce _n in the battery pack 1 has been described a process, the cell _{Ce n-1,} · · · , Ce ₁ can be similarly processed between adjacent cells.

  In the flowchart shown in FIG. 5, in steps S8, S13, and S18, it is determined whether or not the regenerative current is in the normal range. If the regenerative current is out of the normal range, the process is ended. An alarm / display indicating that a regenerative current abnormality has been detected may be output.

  In the abnormal current detection method according to the embodiment of the present invention, an active cell balance circuit that sets an operation mode and a normal current detection range of an active cell balance circuit according to a difference between adjacent cell voltages and performs an equalization operation in the set operation mode. The operation is stopped when the regenerative current of the circuit is out of the normal current detection range. Therefore, the active cell balance circuit does not continue to operate in an abnormal state where the regenerative current in the set operation mode is out of the normal current detection range, so that the battery pack including the active cell balance circuit and the abnormal current detection device Reliability is improved.

1 Battery Pack 2 Battery Module 3 Cell Balance Unit 4 Battery Monitoring ECU
5 Battery control ECU
10 Microcomputer 11 Converter control IC
12,13 FET
14 inductance 15 resistor 16 current monitoring circuit 17 the average current setting circuit _{Ce1, ···, Ce n + 1} , Ce n cells

Claims (8)

Current detection means for detecting the regenerative current in the active cell balance circuit;
An abnormality determination unit that changes a current range for determining whether or not the regenerative current is normal according to an operation mode of the active cell balance circuit and determines whether or not the regenerative current detected by the current detection unit is within a normal range. When,
An abnormal current detection device comprising: The operation mode is:
The abnormal current detection device according to claim 1, wherein the operation is a step-down operation and a step-up operation of constant current charge / discharge.   3. The abnormal current detection device according to claim 1, wherein when the abnormality determination unit determines that the regenerative current is not in a normal range, the operation of the active cell balance circuit is stopped. A battery module comprising a plurality of cells;
An active cell balance circuit;
The abnormal current detection device according to any one of claims 1 to 3,
A battery pack comprising: A first process for detecting a regenerative current in the active cell balance circuit;
A second process for changing a range of a current for determining whether or not the regenerative current is normal according to an operation mode of the active cell balance circuit;
A third process for detecting an abnormal current depending on whether or not the regenerative current is within the range of the determination current changed in the second process;
An abnormal current detection method characterized by comprising: The second process includes
A fourth process of acquiring a cell voltage in the active cell balance circuit and calculating a cell voltage difference from adjacent cell voltages;
A fifth process for setting an operation mode of the active cell balance circuit according to the cell voltage difference;
A sixth process of setting a normal range of the regenerative current according to the set operation mode;
The abnormal current detection method according to claim 5, wherein: 7. The abnormality according to claim 5, further comprising: a seventh process for stopping the operation of the active cell balance circuit when the regenerative current is out of the set normal range in the third process. Current detection method. A cell voltage difference calculation process for calculating a cell voltage difference from each cell voltage acquired from the active cell balance circuit and a cell voltage adjacent to each cell voltage;
An operation mode setting process for setting an operation mode of the active cell balance circuit according to the cell voltage difference;
A normal range setting process for setting a normal range of the regenerative current according to the set operation mode;
Regenerative current determination processing for determining whether or not the regenerative current in the active cell balance circuit is within a set normal range;
A program that causes a computer to execute.