Battery device of electric vehicle

Abstract

To provide a battery device of an electric vehicle, easily and effectively utilizing power delivered from a voltage cell due to processing for cell balance.SOLUTION: A battery device of an electric vehicle, mounted on an electric vehicle so as to supply power for travelling comprises: a battery having a plurality of battery cells; an adjustment circuit capable of adjusting voltage of the plurality of battery cells; and a controller for controlling the adjustment circuit so as to balance the voltage of the plurality of battery cells. When four battery cells connected in series or 4×n battery cells having n sets connected in parallel (n is an integer of 2 or more), each set having 4 connected in series, is defined as one unit of cell column, the adjustment circuit is capable of drawing current from each one unit of cell column. The controller controls the adjustment circuit so that voltages balance between a plurality of units of cell columns.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a battery device for an electric vehicle.

Background Art

[0002] The battery of an electric vehicle includes a plurality of battery cells. Patent Document 1 describes an apparatus that performs cell balancing processing for equalizing the voltages of a plurality of battery cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventional cell balancing processing was a process of equalizing the voltages among a plurality of battery cells in units of one battery cell. The inventors of the present invention considered whether the power transmitted from the battery cells in the cell balancing processing could be effectively utilized.

[0005] An object of the present invention is to provide a battery device for an electric vehicle that can easily and effectively utilize the power transmitted from a voltage cell in cell balancing processing.

Means for Solving the Problems

[0006] The battery device for an electric vehicle according to the present invention is a battery device for an electric vehicle mounted on an electric vehicle and supplying power for running, comprising a battery having a plurality of battery cells, an adjustment circuit capable of adjusting the voltages of the plurality of battery cells, a controller that controls the adjustment circuit to equalize the voltages of the plurality of battery cells, and The adjustment circuit is configured such that four of the battery cells connected in series, or 4×n of the battery cells in which n sets (n is an integer of 2 or more) of four cells connected in series are connected in parallel, are regarded as one unit of cell string, and current can be drawn from each unit of the cell string. The controller controls the adjustment circuit so that the voltage is equalized among a plurality of units of the cell strings.

Advantages of the Invention

[0007] According to the present invention, when current is drawn from a battery cell via the adjustment circuit, a voltage four times that of one battery cell is output from the above cell string. This voltage can be applied as the power supply voltage for various devices mounted on an electric vehicle. Therefore, the power sent from the cell string via the adjustment circuit can be used as the operating power for various devices, and the power can be easily and effectively utilized.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] FIG. 1 is a block diagram showing an electric vehicle equipped with a battery device according to an embodiment of the present invention. The electric vehicle 1 includes drive wheels 2, an electric motor 3 that drives the drive wheels 2, a battery 41 that supplies power for traveling to the electric motor 3, an inverter 5 that converts power between the battery 41 and the electric motor 3, a traveling operation unit 6 that enables traveling operations, a vehicle controller 9 that controls traveling, a controller 42 that manages the battery 41, and an equipment battery 8 that supplies a power supply voltage to the vehicle controller 9 and the controller 42. The traveling operation unit 6 includes a steering operation unit 6a such as a steering wheel, an accelerator operation unit 6b such as an accelerator pedal, and a brake operation unit 6c such as a brake pedal.

[0011] The battery device 4 according to the present embodiment includes the battery 41 and the controller 42 described above.

[0012] The battery 41 is a lithium-ion secondary battery, a nickel-metal hydride secondary battery, or the like, and includes a plurality of battery cells 41a (see FIG. 2) connected in series and in parallel. The battery 41 outputs a voltage higher than that of the equipment battery 8 (for example, 100 V). Note that the battery 41 may have a configuration including a plurality of battery cells and is not limited to the above types.

[0013] The controller 42 is a microcomputer that operates according to a control program stored in the storage unit 42a. The controller 42 performs management processing of the battery 41. The management processing includes receiving measured values of the temperature, voltage, and current of the battery 41, calculating the SOC (State Of Charge) of the battery 41 based on the measured values, etc., and determining the charge / discharge possible power Win and Wout of the battery 41.

[0014] The controller 42 further performs cell balancing processing for equalizing the voltages of the plurality of battery cells 41a constituting the battery 41.

[0015] In addition, in the present embodiment, an example is shown in which the controller 42 performs both cell balancing processing and battery 41 management processing. However, a configuration may be adopted in which a controller that performs cell balancing processing and a controller that performs battery 41 management processing are provided separately. In such a configuration, the controller included in the battery device 4 of the present embodiment corresponds to the controller that performs cell balancing processing.

[0016] The device battery 8 is not particularly limited, but is, for example, a lead-acid battery. The device battery 8 supplies a 12V system power supply voltage to the power line L1. The 12V system power supply voltage is, for example, a voltage of 11V or more and 17V or less. The device battery 8 receives charging power via the power line L1 from a generator or a DC / DC converter (not shown). When the charging power is sent, the voltage of the power line L1 becomes about 14V to 16V. The device battery 8 supplies the power supply voltage to the vehicle controller 9 and the controller 42 of the battery device 4 via the power line L1.

[0017] The vehicle controller 9 is a microcomputer that operates according to a control program stored in the storage unit 9a. The vehicle controller 9 receives an operation signal from the driving operation unit 6, communicates with the controller 42, and checks whether the required discharge or charge of the battery 41 exceeds the dischargeable power Wout and the chargeable power Win. Then, the vehicle controller 9 drives the inverter 5 according to the above operation signal and the result of the above check. By such control, the running of the electric vehicle 1 according to the driving operation and the state of the battery 41 is realized.

[0018] <Configuration of Cell Balancing Processing> FIG. 2 is a diagram showing an adjustment circuit for equalizing the voltages of battery cells.

[0019] The battery 41 includes a plurality of battery cells 41a. The voltage of one battery cell 41a is 1 / m (where m is an integer of 2 or more, specifically m is 4) of the charging voltage of the device battery 8, such as 3V to 4.3V. In the battery 41, a large number of battery cells 41a are connected in series and in parallel, and with this configuration, a high output voltage and a large capacity are realized. FIG. 2 shows a very small part of all the battery cells 41a included in the battery 41.

[0020] The plurality of battery cells 41a of the battery 41 are not particularly limited, but as shown in FIG. 2, they are divided into a plurality of battery blocks R41, and the plurality of battery blocks R41 are further connected in series. In one battery block R41, m (m is an integer of 2 or more, specifically m is 4) battery cells 41a connected in series are regarded as one unit cell string Q41, and a plurality of units (for example, 3) of cell strings Q41 are connected in parallel.

[0021] The battery 41 is provided with an adjustment circuit 43 capable of adjusting the voltage of the plurality of battery cells 41a. The adjustment circuit 43 is configured such that current can be drawn out for each unit cell string Q41, and by drawing out the current, the voltage can be adjusted for each unit cell string Q41. As an example, the adjustment circuit 43 includes switches SWa, SWa that can disconnect the parallel connection of the plurality of cell strings Q41 included in the battery block R41. Further, the adjustment circuit 43 includes connection switches SWb~SWb, SWc that connect each cell string Q41 and the current line L11 corresponding to the plurality of cell strings Q41 respectively. For example, when the switches SWa, SWa are in the open state and one of the three switches SWb and the switch SWc on the ground side are switched to the closed state, the cell string Q41 and the current line L11 can be connected so that current can be drawn from one cell string Q41 to the current line L11.

[0022] The current drawn from cell column Q41 can reduce the voltage of the cell column Q41 by flowing it through a resistor (not shown) to consume power. Alternatively, the current drawn from cell column Q41 can be sent to device battery 8 for charging or sent to any device for power consumption to reduce the voltage of the cell column Q41. The controller 42 can adjust the voltage of the cell column Q41 by switching the switches SWa, SWb, and SWc as described above.

[0023] The current line L11 is provided with a first switch SW1 connectable to the power line L1 of the controller 42 and the vehicle controller 9, and a second switch SW2 connectable to the device battery 8.

[0024] The controller 42 can perform opening and closing control of each switch SWa, SWb, SWc of the adjustment circuit 43, and the first switch SW1 and the second switch SW2 of the current line L11.

[0025] The adjustment circuit 43 further includes a plurality of voltage sensors sv for detecting the voltage of each cell column Q41. Each voltage sensor sv is connected between the anode and the cathode of each cell column Q41. The voltage information detected by the voltage sensor sv is sent to the controller 42. The voltage sensor sv detects the voltage between both terminals of each cell column Q41.

[0026] <Control Processing of the Controller> Figures 3 and 4 are flowcharts showing the control processes executed by the controller. During the system operation of the electric vehicle 1, the controller 42 repeatedly executes the control processes of Figures 3 and 4. When the control process is started, first, the controller 42 acquires the state diagnosis result of the equipment battery 8 (step S1). The state diagnosis may be performed, for example, by the vehicle controller 9 or another controller (not shown), and the result may be sent to the controller 42 by communication. The case where the result of the state diagnosis is abnormal corresponds to the case where it is predicted that it will be difficult to maintain the operation of the equipment powered by the equipment battery 8, such as depletion of the charge amount of the equipment battery 8 or a voltage drop of the equipment battery 8 (below a predetermined lower limit voltage).

[0027] Next, the controller 42 determines whether the diagnosis result obtained in step S1 is abnormal (step S2). If it is not abnormal (i.e., if it is normal), the controller 42 proceeds to the cell balancing process of steps S3 to S9.

[0028] Then, first, the controller 42 acquires the voltage value of the cell string Q41 with the lowest voltage among all the battery blocks R41 of the battery 41 (hereinafter referred to as "min column voltage") (step S3). The voltage value is obtained by comparing the outputs of a plurality of voltage sensors sv.

[0029] Next, the controller 42 connects the equipment battery 8 to the current line L11 by switching the second switch SW2 to the closed state (step S4). Instead of the equipment battery 8, the controller 42 may connect a resistor or another load between the current line L11 and the ground.

[0030] Next, the controller 42 executes the voltage adjustment process for each cell string Q41 of the plurality of battery blocks R41 in order by the loop process of steps S5 to S11. That is, by the determination process in step S10 and the process of moving the battery block R41 to be processed in step S11 to the next one, the process is executed for each battery block R41 one by one in order. Also, by the determination process in step S8 and the process of moving the cell string Q41 to be targeted in step S9 to the next one, the processes in steps S6 and S7 are executed for each cell string Q41 in one battery block R41 one by one in order.

[0031] During the above loop process, the controller 42 first determines whether the voltage of the battery block R41 to be processed (the y-th battery block R41) is equal to or higher than the threshold value than the min column voltage value (step S5). In normal times, since the switches SWa and SWa are closed, the voltages of the three cell strings Q41 in one battery block R41 are equal. Therefore, the voltage can be compared for each battery block R41. For the above threshold value, it is only necessary to set the minimum value of the voltage difference to be equalized.

[0032] If the result of step S5 is NO, the controller 42 moves the process to step S10 and determines whether the process has been performed for all the battery blocks R41 (step S10). If the result is NO, the process target is moved to the next battery block R41, that is, updated to y←(y + 1) (step S11), and the process returns to step S5.

[0033] On the one hand, if the result of step S5 is YES, the controller 42 sets the x-th cell string Q41 among the multiple cell strings Q41 included in the battery block R41 to be processed as the processing target, and connects the cell string Q41 to the current line L11 (step S6). Specifically, first, the controller 42 switches the switches SWa and SWa of the battery block R41 to be processed to the open state. Next, the controller 42 switches the switch SWb corresponding to the cell string Q41 to be processed among the three switches SWb and the ground-side switch SWc to the closed state. By this switching, the cell string Q41 to be processed is connected to the current line L11, and current is drawn from the cell string Q41 to the current line L11. Since the voltage of the cell string Q41 is a voltage capable of charging the device battery 8, the current can be sent to the device battery 8 via the current line L11 without boosting, and the device battery 8 can be charged.

[0034] Subsequently, the controller 42 adjusts the voltage of the cell string Q41 to be processed so as to drop to the min column voltage (step S7). Specifically, while monitoring the voltage of the cell string Q41 to be processed, when the voltage drops to the min column voltage, the controller 42 returns the switches switched in step S6 to their original states.

[0035] Then, the controller 42 determines whether processing has been performed for all the cell strings Q41 in the battery block R41 to be processed (step S8). If the result of this determination is NO, the controller 42 moves the processing target to the next cell string Q41, that is, updates x←x + 1 (step S9), and returns the processing to step S6.

[0036] When processing has been executed for all the cell strings Q41 of all the battery blocks R41 and the determination result in step S10 is YES, the controller 42 exits the loop process and ends one control process. Then, at the start timing of the next control process, the process from step S1 is repeated again.

[0037] If the result of the determination process in step S2 indicates an abnormality in the device battery 8, the controller 42 transfers the process to the abnormality handling process in steps S12 to S18. The abnormality handling process is a process for coping with the abnormality of the device battery 8 by substituting the power supply of the device battery 8 with the power supply from the battery 41 via the adjustment circuit 43. After transferring the process to the abnormality handling process, first, the controller 42 connects the power line L1 and the current line L11 by switching the first switch SW1 to the closed state (step S12).

[0038] Next, the controller 42 connects a plurality of cell strings Q41 of the battery 41 to the current line L11 and draws current from the plurality of cell strings Q41 to the current line L11 (step S13). The current is supplied to the controller 42 and the vehicle controller 9 via the power line L1. Since the voltage of the cell string Q41 is equivalent to the operating voltage of the controller 42 and the vehicle controller 9, the above current can be sent to the controller 42 and the vehicle controller 9 to be used as an operating power source. Even if the voltage of the device battery 8 drops due to the current, the operations of the controller 42 and the vehicle controller 9 are maintained.

[0039] Note that in the determination process of step S2, when the device battery 8 is determined to be abnormal and the abnormality handling process in steps S12 to S18 is executed, in step S12, a process of disconnecting the device battery 8 from the power line L1 by switching the switch SW3 to the open state may be performed. Thereby, the abnormal device battery 8 can be disconnected, and it can be suppressed that the device battery 8 absorbs the current of the cell string Q41. Alternatively, when the abnormality of the device battery 8 is simply a charging depletion, the connection of the device battery 8 to the power line L1 may be maintained. Thereby, the current drawn in step S13 is also supplied to the device battery 8, and the charge amount of the device battery 8 can be restored.

[0040] When the current extraction starts in step S13, the controller 42 monitors the voltage or state of charge (SOC) of the cell string Q41 connected to the current line L11 (step S14). If there is a cell string Q41 whose voltage or SOC has reached the lower limit, the controller 42 disconnects the cell string Q41 from the current line L11 (step S15). Specifically, the controller 42 opens the corresponding switch SWb among the three switches SWb to SWb and keeps the corresponding switch among the switches SWa and SWb in the open state. By disconnecting the cell string Q41 whose SOC and voltage have decreased in this way, it is possible to prevent the cell string Q41 from absorbing power from other battery blocks R41 or other cell strings Q41.

[0041] Subsequently, the controller 42 determines whether all of the plurality of cell strings Q41 connected to the current line L11 in step S13 have been disconnected from the current line L11 by the process of step S15 (step S16). If the determination result is NO, the controller 42 returns the process to step S14 and repeats the processes of steps S14 to S16.

[0042] Note that, as a method for selecting the cell column Q41 from which current is drawn in steps S13 and S14, various methods can be adopted. For example, the controller 42 may select q battery blocks R41 that are not adjacent to each other and not connected in series among the plurality of battery blocks R41 included in the battery 41. Then, the controller 42 may draw current simultaneously from one cell column Q41 included in each of the q battery blocks R41, for example, the cell column Q41 in the third column. According to such a selection method, current can be drawn simultaneously from the q cell columns Q41, enabling a stable power supply. When paying attention to two battery blocks R41 that are adjacent to each other and connected in series, the ground-side switch SWc of the first battery block R41 to which the cathode side is connected and the switches SWb to SWb of the second battery block R41 to which the anode side is connected are located at the same node. And the switch SWc and the switch SWb located at the same node cannot be switched to the closed state simultaneously. Therefore, current cannot be drawn simultaneously from two battery blocks R41 that are adjacent to each other and connected in series. Therefore, the controller 42 selects q battery blocks R41 that are not adjacent to each other and not connected in series as described above. Also, the controller 42 may not draw current from all the cell columns Q41 of one battery block R41, but leave one or more cell columns Q41 and draw current from the other cell columns Q41 (for example, the cell column Q41 in the third column). By this selection, even if one or more cell columns Q41 are discharged in one battery block R41, the charge amounts of the remaining cell columns Q41 (for example, the cell columns Q41 in the first and second columns) are maintained. Therefore, the high-voltage output from the battery 41 can be maintained using the power of the cell columns Q41 whose charge amounts are maintained.

[0043] If the result of the determination process in step S16 is YES, the controller 42 determines whether there remains a cell string Q41 connected to the current line L11 in the battery 41 and from which current can be drawn (step S17). If the result is YES, the controller 42 returns the process to step S13. Then, the controller 42 repeats the process from step S13 for the plurality of cell strings Q41 from which current can be drawn.

[0044] Then, if the cell strings Q41 from which current can be drawn are exhausted and the determination result in step S17 becomes NO, the controller 42 performs a warning process for power depletion of the battery 41 (step S18) and ends the control process.

[0045] Note that the determination process in step S17 may be a process of determining whether there remains a cell string Q41 from which current can be drawn for all the cell strings Q41 of the battery 41. With this configuration, when an abnormality occurs in the device battery 8, all the power stored in the battery 41 can be used to maintain the operations of the vehicle controller 9 and the controller 42. Alternatively, the determination process in step S17 may be a process of determining whether there remains a cell string Q41 from which current can be drawn within a range excluding one or two cell strings Q41 of each battery block R41. According to this configuration, it is possible to maintain the operations of the vehicle controller 9 and the controller 42 for a long time while leaving a margin for outputting a high voltage in the battery 41.

[0046] By the control process as described above, it is possible to perform a cell balance process for equalizing the voltage for each unit cell string Q41 with four serially connected battery cells 41a as one unit cell string Q41. At this time, the current drawn from the cell string Q41 can be supplied to a 12V system load (including the equipment battery 8) without performing boosting or the like. Also, by the control process as described above, when the equipment battery 8 malfunctions, the adjustment circuit 43 for equalizing the voltage can be used to efficiently supply 12V system power from the battery 41 to the controller 42 and the vehicle controller 9. Therefore, it becomes possible to easily maintain the operations of the controller 42 and the vehicle controller 9.

[0047] The program of the control process described above is stored in a non-transitory computer readable medium such as the storage unit 42a of the controller 42. The controller 42 may be configured to read a program stored in a portable non-transitory recording medium and execute the program. The above portable non-transitory storage medium may store the program of the control process described above.

[0048] As described above, according to the battery device 4 of the present embodiment, it includes a battery 41 having a plurality of battery cells 41a, an adjustment circuit 43 capable of adjusting the voltages of the plurality of battery cells 41a, and a controller 42 for controlling the adjustment circuit 43. And the adjustment circuit 43 is configured to be able to draw current for each unit cell string Q41 with four serially connected battery cells 41a as one unit cell string Q41. Further, the controller 42 controls the adjustment circuit 43 so that the voltages are equalized among a plurality of unit cell strings Q41. Therefore, the power output from the cell string Q41 via the adjustment circuit 43 becomes equal to the power of the equipment battery 8 such as the 12V system. Therefore, the power output via the adjustment circuit 43 can be sent to a 12V system device and used as power supply power. Thus, the power output to the outside of the battery 41 by the process of equalizing the voltage can be easily and effectively utilized.

[0049] Furthermore, according to the battery device 4 of the present embodiment, a first switch SW1 is provided that can send the current drawn from the cell string Q41 through the adjustment circuit 43 as a power supply current to circuits in the control system of the electric vehicle 1 such as the controller 42 and the vehicle controller 9. The controller 42 can control the opening and closing of the first switch SW1. With such a configuration, when an abnormality occurs in the 12V system power supply voltage, etc., the 12V system power supply voltage can be supplied from the battery 41 to the circuits in the control system through the adjustment circuit 43. Therefore, even when an abnormality occurs in the 12V system power supply voltage, the current drawn from the battery 41 through the adjustment circuit 43 can be effectively utilized, and it is possible to suppress the system of the electric vehicle 1 from stopping.

[0050] Furthermore, according to the battery device 4 of the present embodiment, based on an abnormality in the device battery 8, the controller 42 controls the first switch SW1 to the closed state and controls the adjustment circuit 43 so that a current is drawn from the cell string Q41. Therefore, even when the supply of the 12V system power supply voltage is likely to be interrupted due to an abnormality in the device battery 8, the current drawn from the battery 41 through the adjustment circuit 43 can be effectively utilized, and it is possible to suppress the system of the electric vehicle 1 from stopping.

[0051] Furthermore, according to the battery device 4 of the present embodiment, when the device battery 8 is normal, if the voltage difference between the cell strings Q41 of multiple units is equal to or less than the threshold value, the controller 42 does not perform control to draw current from the cell string Q41 via the adjustment circuit 43. Specifically, the case where the voltage difference is equal to or less than the above-mentioned threshold value corresponds to the case where the difference between the min column voltage and the voltage of the cell string Q41 to be processed is equal to or less than the threshold value. On the other hand, when the device battery 8 is abnormal, the controller 42 performs control to draw current from the cell string Q41 via the adjustment circuit 43 even if the voltage difference between the cell strings Q41 of multiple units is equal to or less than the threshold value. Specifically, the controller 42 performs control to draw the above-mentioned current regardless of the voltage between the cell strings Q41. Therefore, when the supply of the 12V system power supply voltage is likely to be interrupted due to an abnormality of the device battery 8, even if the voltages of the cell strings Q41 are equalized, the 12V system power supply voltage can be supplied to the control system circuit of the electric vehicle 1 via the adjustment circuit 43. Thus, it is possible to further suppress the system of the electric vehicle 1 from stopping during an abnormality of the device battery 8.

[0052] Furthermore, according to the battery device 4 of the present embodiment, when the device battery 8 is abnormal, the controller 42 controls the adjustment circuit 43 so that current is drawn from two or more cell strings Q41 simultaneously. Therefore, a more stable power supply voltage can be supplied from the adjustment circuit 43 to the system of the electric vehicle 1 during an abnormality of the device battery 8. Thus, it is possible to further suppress the system of the electric vehicle 1 from stopping.

[0053] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, as a cell string of one unit capable of adjusting the voltage by extracting current by the adjustment circuit 43, four battery cells 41a connected in series are shown as an example. However, 4×n battery cells in which n sets (n is an integer of 2 or more) of a set of four cells connected in series are connected in parallel can also be applied as the above-described cell string of one unit. Even in this case, the 12V system power supply voltage can be replaced by the voltage of the cell string of one unit. Further, in the above embodiment, when adjusting the voltage of the cell string Q41, an example of extracting current from the cell string Q41 to lower the voltage is shown, but an operation of supplying current to the cell string Q41 to raise the voltage may be combined. In addition, details shown in the embodiment, such as the number of cell strings included in one battery block, the connection form of a plurality of cell strings included in one battery block, the switch configuration for adjusting the voltage of each cell string, the switch configuration for connecting the device battery 8 and the current line L11, and the switch configuration for connecting the power line L1 of the control system and the current line L11, can be appropriately changed without departing from the gist of the invention.

Explanation of Signs

[0054] 1 Electric vehicle 2 Driving wheels 3 Electric motor 4 Battery device 5 Inverter 6 Travel operation unit 8 Device battery 9 Vehicle controller 9a Storage unit 41 Battery 41a Battery cell R41 Battery block Q41 Cell string 42 Controller 42a Storage unit 43 Adjustment circuit SWa, SWb, SWc Switches sv Voltage sensor SW1 First switch SW2 Second switch L1 Power line L11 Current Line

Claims

1. A battery device for an electric vehicle that is mounted on an electric vehicle and supplies electric power for traveling, A battery having a plurality of battery cells; An adjustment circuit capable of adjusting the voltage of the plurality of battery cells; a controller for controlling the regulation circuit to balance the voltages of the plurality of battery cells; Equipped with the adjustment circuit is configured to be capable of drawing current for each of the four battery cells connected in series, or for each of the four battery cells connected in series, i.e., n sets of four battery cells connected in parallel (n is an integer of 2 or more), each of which is regarded as one unit of a cell string, A battery device for an electric vehicle, wherein the controller controls the adjustment circuit so as to balance the voltages among a plurality of units of the cell strings.

2. The electric vehicle includes a vehicle controller and an equipment battery that supplies power to the vehicle controller; a first switch capable of sending a current drawn from the string of cells via the regulating circuit to the controller or the vehicle controller; 2. The battery device for an electric vehicle according to claim 1, wherein the controller controls the first switch.

3. 3. The battery device for an electric vehicle according to claim 2, wherein the controller controls the first switch to a closed state based on an abnormality in the equipment battery, and controls the adjustment circuit so that current is drawn from the cell string.

4. The controller: When the device battery is normal, if a voltage difference between the plurality of units of cell strings is equal to or less than a threshold value, a process of controlling the adjustment circuit to draw current from the cell strings is not performed; On the other hand, when the equipment battery is abnormal, the adjustment circuit is controlled so that current is drawn from the cell strings even if the voltage difference between the multiple units of cell strings is below a threshold value.

5. The controller:

4. A battery device for an electric vehicle according to claim 3, wherein said adjustment circuit is controlled so that current is drawn simultaneously from two or more units of said cell strings when said equipment battery is abnormal.

Images