Battery control unit

Abstract

This technology reduces the time required to match the State of Charge (SOC) of all batteries and suppresses circulating current between batteries. [Solution] The battery control device identifies one or more first batteries from among three or more batteries whose SOC is equal to or greater than a first threshold, identifies two or more second batteries from among three or more batteries whose SOC is less than the first threshold, configures a series-parallel configuration in which the two or more identified second batteries are connected in parallel and one or more first batteries are connected in series to the two or more identified second batteries, and controls the switching unit to supply power to the drive motor, and to release the series-parallel configuration when the difference in SOC of the three or more batteries falls below the second threshold.

Description

[[Technical Field]]

[0001] The present disclosure relates to a battery control apparatus. [[Background Art]]

[0002] Conventionally, there has been known a technique for equalizing differences in remaining capacity between a plurality of replaceable batteries.

[0003] For example, Patent Document 1 discloses a control device comprising: a power supply unit on which a plurality of replaceable batteries are mounted; an output unit that operates using electric power from the power supply unit; an acquisition unit that acquires remaining capacity information relating to the respective remaining capacities of the plurality of batteries; and a control unit that controls charging and discharging between the plurality of batteries based on the remaining capacity information acquired by the acquisition unit such that a difference in remaining capacity between the plurality of batteries falls within an allowable range. [[Prior Art Documents]] [[Patent Documents]]

[0004] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2022-149726 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] In an electric vehicle, particularly an electric vehicle that uses a plurality of replaceable batteries connected in series, it is necessary to replace all batteries with batteries having a high SOC when replacing batteries. This is because even if some of the batteries can be replaced with batteries having a high SOC, the available capacity is limited by the battery having the lowest SOC while the vehicle is traveling, which makes it impossible to utilize the capacity of the batteries having a high SOC.

[0006] One method for adjusting the State of Charge (SOC) of multiple batteries is to switch series-connected batteries to parallel connections and flow current from the battery with the highest SOC to the battery with the lowest SOC. In this method, for example, as disclosed in Patent Document 1, current is flowed from the battery with the highest SOC to the battery with the lowest SOC so that the difference in remaining charge between the batteries falls within an acceptable range. However, this method has the problem that it takes time to match the SOC of all batteries. In addition, there is the problem that the capacity of the batteries is consumed due to the flow of circulating current between them.

[0007] In light of these circumstances, the purpose of this disclosure is to provide a technology that shortens the time required to match the State of Charge (SOC) of all batteries and suppresses circulating current between batteries. [Means for solving the problem]

[0008] A battery control device according to one embodiment of the present disclosure is a battery control device applied to a battery system comprising three or more batteries that supply power to a vehicle's drive motor, and a switching unit that switches the connection state of the three or more batteries, comprising one or more processors and one or more memories that are communicably connected to the one or more processors, wherein the one or more processors identify one or more first batteries from the three or more batteries whose SOC is equal to or greater than a first threshold, identify two or more second batteries from the three or more batteries whose SOC is less than the first threshold, configure a series-parallel state in which the connection state of the identified two or more second batteries is in parallel and the connection state of the one or more first batteries to the identified two or more second batteries is in series, and supply power to the drive motor, and controls the switching unit to release the series-parallel state when the SOC difference of the three or more batteries falls below the second threshold. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, the time required to match the State of Charge (SOC) of all batteries can be reduced, and circulating currents flowing between batteries can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the general configuration of a vehicle equipped with a battery control device according to the first embodiment of the present disclosure. [Figure 2] This is a circuit diagram showing an example of the arrangement of the battery and switching unit in a battery system according to the first embodiment of this disclosure. [Figure 3] This is a block diagram showing an example configuration of a battery control device according to the first embodiment of the present disclosure. [Figure 4] This diagram illustrates the series-parallel state configured for SOC adjustment in the first embodiment of this disclosure. [Figure 5] This figure illustrates an example of the time variation of current during SOC adjustment in the first embodiment of this disclosure. [Figure 6] This figure illustrates an example of the time change of the SOC during SOC adjustment in the first embodiment of this disclosure. [Figure 7] This is a flowchart illustrating an example of operation of a battery control device according to the first embodiment of this disclosure. [Figure 8] This is a circuit diagram showing an example of the arrangement of the battery and switching unit in a battery system according to a second embodiment of the present disclosure. [Figure 9] This is a flowchart illustrating an example of operation of a battery control device according to a second embodiment of the present disclosure. [Modes for carrying out the invention]

[0011] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0012] <1. First Embodiment> (1-1. Vehicles) Referring to Figure 1, Vehicle 1 is an electric vehicle that transmits the drive torque output from a drive motor 10, which generates the drive torque of Vehicle 1, to the wheels. Examples of electric vehicles include BEV (Battery Electric Vehicle), HEV (Hybrid Electric Vehicle), PHEV (Plug-in Hybrid Electric Vehicle), or FCEV (Fuel Cell Electric Vehicle).

[0013] Furthermore, the combination of drive wheels and drive method are not limited. For example, Vehicle 1 may be a front-wheel drive vehicle, a rear-wheel drive vehicle, or a four-wheel drive vehicle. Also, Vehicle 1 may be an electric vehicle equipped with two drive motors, including a front-wheel drive motor and a rear-wheel drive motor. Alternatively, Vehicle 1 may be an electric vehicle equipped with a drive motor corresponding to each wheel.

[0014] The drive motor 10 is configured, for example, as a three-phase AC motor. In this case, a rotating magnetic field is formed when three-phase AC power is supplied to the stator (not shown) included in the drive motor 10, causing the rotor (not shown) included in the drive motor 10 to rotate and output drive torque. The drive motor 10 also has a function of regenerative power generation, where the rotor rotates in response to the rotational torque of the wheels when three-phase AC current is not supplied to the stator. However, the drive motor 10 is not limited to a three-phase AC motor; any known or arbitrary motor capable of generating drive torque can be used.

[0015] Vehicle 1 includes a battery system 20 that supplies power to the drive motor 10, and a battery control device 30 that controls the battery system 20.

[0016] The battery system 20 includes at least three or more batteries 22 that supply electric power to the drive motor 10, and a switching unit 24 that switches the connection state of the three or more batteries 22. Although the batteries 22 shown in FIG. 1 are connected in series during normal use, the present disclosure is not limited thereto, and the batteries may be connected in parallel during normal use.

[0017] The battery 22 is a secondary battery capable of exchanging electric power with the drive motor 10. The battery 22 is, for example, a lithium ion battery with a rated voltage of 200 V or an all-solid-state battery. However, the rated voltage and type of the battery 22 are not particularly limited as long as it can exchange electric power with the drive motor 10. Hereinafter, for simplicity, a case where the vehicle 1 includes three batteries 22a, 22b, and 22c (hereinafter collectively referred to as "the battery 22" when no particular distinction is required) will be described as an example, but the number of batteries 22 in the present disclosure is not particularly limited as long as it is three or more.

[0018] The battery 22 is a replaceable battery. Here, the term "replaceable" means that the battery 22 is detachably attachable to the vehicle 1. Specifically, "replaceable" may mean that the battery 22 can be removed from a battery case (not shown) mounted on the vehicle 1 by releasing a lock mechanism (not shown) of the battery 22 for replacement or charging. Furthermore, "replaceable" may also mean that the battery 22 can be reattached to the battery case mounted on the vehicle 1 after replacement or charging is completed, and the lock mechanism of the battery 22 can be locked. The present disclosure does not particularly limit the structure for detachably attaching the battery 22 to the vehicle 1, and any known or arbitrary structure may be employed. However, the battery 22 in the present disclosure does not necessarily need to be replaceable, and may be non-replaceable.

[0019] The switching unit 24 includes a plurality of switches electrically connected to the battery control device 30. The switches receive commands from the battery control device 30 and switch the connection state of the battery 22. The switches may include known or arbitrary switching elements such as relays or semiconductor elements. The number of switches can be set appropriately according to the number of batteries 22 and is not particularly limited.

[0020] Referring to Figure 2, an example of the arrangement of the battery 22 and the switching unit 24 will be described in detail. The circuit shown in Figure 2 includes batteries a, b, and c as the battery 22, and switches SW-A, SW-B, SW-C, SW-D, SW-E, SW-F, SW-G, SW-H, SW-I, and SW-J as the switching unit 24. In Figure 2, "+" means connected to the positive bus of the inverter 40 via the converter 50, and "-" means connected to the negative bus of the inverter 40 via the converter 50. Switches SW-A to J can be appropriately arranged to satisfy the following four conditions, for example, when batteries a, b, and c are used as the battery 22. - Conditions under which batteries a through c can be connected in series or in parallel. - Conditions under which batteries b and c can be connected in parallel, and battery a can be connected in series to batteries b and c. - Conditions under which batteries a and b can be connected in parallel, and battery c can be connected in series to batteries a and b. - Conditions under which batteries a and c can be connected in parallel, and battery b can be connected in series to batteries a and c. In Figure 2, switches SW-A to J are shown as unipolar double-throw switching elements, but this disclosure is not limited to this.

[0021] Returning to Figure 1, in addition to the battery system 20 described above, vehicle 1 further includes an inverter 40 electrically connected to the drive motor 10 and a converter 50 electrically connected to the inverter 40.

[0022] The inverter 40 includes a known or arbitrary inverter circuit (not shown) that converts the DC power swept from the battery 22 into, for example, three-phase AC power and supplies it to the stator of the drive motor 10. This inverter circuit converts the three-phase AC power regenerated by the stator of the drive motor 10 into DC power and supplies it to the converter 50. The inverter 40 is driven by a vehicle control device 60 which includes one or more electronic control units (ECUs).

[0023] The converter 50 adjusts the voltage output by the battery 22 and the voltage output by the inverter 40. That is, the converter 50 includes a known or arbitrary step-up / step-down circuit (not shown) for stepping up or stepping down power. The drive of the converter 50 is controlled by the vehicle control device 60. In this case, the converter 50 may receive commands from the battery control device 30, as will be described later.

[0024] In addition, Vehicle 1 is equipped with known or arbitrary steering devices (not shown) and brake devices (not shown) as equipment used for driving control. The steering devices and brake devices are driven by the vehicle control device 60.

[0025] Vehicle 1 may also include an ambient environment sensor (not shown), such as an onboard camera or distance measuring sensor, for detecting the environment around Vehicle 1; a vehicle state sensor (not shown) for detecting the state of Vehicle 1; and a position detection sensor (not shown) for detecting the position of Vehicle 1.

[0026] (1-2. Battery control device) The battery control device 30 according to this embodiment will be described in detail with reference to Figure 3.

[0027] (1-2-1. Example Configuration) The battery control device 30 functions as a device applied to the battery system 20 by having one or more processors, such as CPUs (Central Processing Units), execute a computer program. This computer program is a program that causes the processor to execute the operations that the battery control device 30 is to perform, as described later. The computer program executed by the processor may be recorded on a recording medium that functions as a memory unit 32, as described later, or on a recording medium built into the battery control device 30 or on any external recording medium that can be attached to the battery control device 30.

[0028] The recording medium for storing computer programs may include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs, DVDs, and Blu-ray®; magneto-optical media such as floppy disks; memory elements such as RAM and ROM; flash memory such as USB memory and SSDs; and other media capable of storing programs.

[0029] The battery control device 30 comprises at least a processing unit 31 and a storage unit 32. The battery control device 30 may be electrically connected to the vehicle control device 60, or some or all of its components may be provided in the vehicle control device 60.

[0030] The processing unit 31 comprises one or more processors such as a CPU and various peripheral components. Part or all of the processing unit 31 may consist of updatable components such as firmware, or it may be a program module that is executed by instructions from the CPU or the like.

[0031] The memory unit 32 is composed of one or more memory elements such as RAM or ROM that are connected to the processing unit 31 in a communicative manner. However, the type and number of memory units 32 are not particularly limited. The memory unit 32 stores information such as computer programs executed by the processing unit 31, various parameters used in arithmetic processing, detection data, and calculation results. Specifically, the memory unit 32 has pre-stored information such as first threshold to third threshold values ​​for determining the connection status of the battery 22.

[0032] (1-2-2. Functional Configuration of the Processing Unit) The functional configuration of the processing unit 31 of the battery control device 30 will now be described. The processing unit 31 includes a replacement detection unit 311, a SOC acquisition unit 312, a connection status determination unit 313, an SOC adjustment unit 314, a requested voltage acquisition unit 315, and a voltage control unit 316. Each of these units is a function realized by the execution of a computer program by one or more processors such as a CPU. However, some or all of these units may be configured using analog circuits. Note that the requested voltage acquisition unit 315 and the voltage control unit 316 are not essential components for achieving the effects of this disclosure and can be omitted.

[0033] (Replacement detection unit) The replacement detection unit 311 detects that the battery 22 has been replaced. Specifically, the replacement detection unit 311 detects that the locking mechanism has been released and the battery 22 has been removed from the battery case, and that the new battery 22 has been installed in the battery case and the locking mechanism has been locked.

[0034] (SOC acquisition department) The SOC acquisition unit 312 acquires the SOC of the battery 22 and transmits it to the connection status determination unit 313. The SOC can be calculated by known or arbitrary methods, for example, based on the integrated value of charge and discharge currents detected by a current sensor (not shown) provided in the battery system 20, but this disclosure is not limited thereto.

[0035] (Connection status determination unit) The connection status determination unit 313 identifies one or more first batteries 22-1 from among the batteries 22 whose SOC is equal to or greater than a first threshold, and transmits the identification result to the SOC adjustment unit 314. Specifically, the connection status determination unit 313 identifies one or more first batteries 22-1 whose SOC is equal to or greater than a first threshold by comparing the SOC acquired by the SOC acquisition unit 312 with a first threshold previously stored in the storage unit 32.

[0036] Furthermore, the connection status determination unit 313 identifies two or more second batteries 22-2 from the battery 22 whose SOC is less than the first threshold, and transmits the identification result to the SOC adjustment unit 314. Specifically, the connection status determination unit 313 identifies two or more second batteries 22-2 whose SOC is less than the first threshold by comparing the SOC acquired by the SOC acquisition unit 312 with the first threshold previously stored in the storage unit 32.

[0037] (SOC adjustment department) The SOC adjustment unit 314 controls the switching unit 24 to supply power to the drive motor 10 by configuring a series-parallel configuration of three or more batteries 22. Here, "series-parallel configuration" means a configuration in which the connection state of two or more second batteries 22-2 identified by the connection state determination unit 313 is in parallel, and the connection state of one or more first batteries 22-1 to two or more second batteries 22-2 identified by the connection state determination unit 313 is in series. The technical significance of this control by the SOC adjustment unit 314 will be explained below with reference to Figures 4 to 6.

[0038] Here, as an example, suppose that only battery 22a was replaced from among batteries 22a, 22b, and 22c, and that battery 22a, with an SOC of 100%, battery 22b, with an SOC of 90%, and battery 22c, with an SOC of 80%, were connected in series. Furthermore, suppose that the connection state determination unit 313 identified battery 22a as the first battery 22-1, and identified batteries 22b and 22c as the second battery 22-2.

[0039] In this case, as shown in Figure 4, the SOC adjustment unit 314 controls the switching unit 24 to supply power to the drive motor 10 by configuring a series-parallel state in which batteries 22b and 22c are connected in parallel, and battery 22a is connected in series to batteries 22b and 22c. At this time, as shown in Figures 4 and 5, the current I1 flowing through battery 22a, which constitutes the series portion, is twice the current I2 flowing through batteries 22b and 22c, which constitute the parallel portion. Therefore, as shown in Figure 6, the rate at which the SOC of battery 22a decreases is twice the rate at which the SOCs of batteries 22b and 22c decrease. If power is continuously supplied to the drive motor 10 in the series-parallel state shown in Figure 4, a state will occur in which the SOCs of batteries 22a, 22b, and 22c will match, as shown in Figure 6. In this way, the SOCs of batteries 22a, 22b, and 22c are adjusted by the SOC adjustment unit 314.

[0040] Furthermore, "2x" is determined according to the number of second batteries 22-2 connected in parallel, and if the number of second batteries 22-2 is N (where N is a natural number), it becomes Nx. Also, in this disclosure, "match" does not necessarily mean matching in a mathematically strict sense. For example, "match" may mean a match such that the drive motor 10 does not malfunction even when three or more batteries 22 that can be considered to have matching SOCs are connected in series or in parallel to each other and power is supplied to the drive motor 10.

[0041] In other words, by configuring a series-parallel configuration with three or more batteries 22 to supply power to the drive motor 10, the state of charge (SOC) of the series-connected first battery 22-1 and the parallel-connected second battery 22-2 can be reduced at different rates. As a result, after a certain period of time has elapsed since configuring the series-parallel configuration, the SOCs will match. Therefore, there is no need to stop the vehicle 1 to adjust the SOC after replacing a battery 22, and the relatively rapid power consumption of the drive system due to the vehicle 1's operation (hereinafter also referred to as "SOC adjustment operation") can make the SOCs of all batteries 22 match. Furthermore, as in the conventional method, there is no need to switch the series-connected batteries 22 to parallel connection and allow current to flow from the battery 22 with the high SOC to the battery 22 with the low SOC for a long period of time (for example, about 1 hour) in order to match the SOCs of all batteries 22. As a result, the time required to match the SOCs of all batteries 22 can be shortened compared to the conventional method, and the circulating current flowing between the batteries 22 can be suppressed.

[0042] Here, the connection state determination unit 313 and the SOC adjustment unit 314 may perform the following processing when configuring the series-parallel state described above. That is, the connection state determination unit 313 selects one or more batteries 22 to be connected to one or more first batteries 22-1 from among the two or more second batteries 22-2 based on the SOC of two or more identified second batteries 22-2, and transmits the selection result to the SOC adjustment unit 314. When the SOC adjustment unit 314 receives the selection result from the connection state determination unit 313, it controls the switching unit 24 to connect the one or more identified first batteries 22-1 and the selected battery 22 in series to supply power to the drive motor 10. When the SOC difference of the two or more second batteries 22-2 falls below the third threshold, the SOC adjustment unit 314 cancels the series connection and controls the switching unit 24 to configure a series-parallel state to supply power to the drive motor 10. This makes it possible to match the SOC of all batteries 22 by configuring the series-parallel configuration described above, even if the SOCs of three or more batteries 22 are not the same, without stopping the vehicle 1.

[0043] Here, as an example, suppose that the SOC of battery 22a is 100%, the SOC of battery 22b is 80%, and the SOC of battery 22c is 70%, and the connection state determination unit 313 identifies battery 22a as the first battery 22-1, and batteries 22b and 22c as the second battery 22-2. In this case, the SOC adjustment unit 314 controls the switching unit 24 to connect battery 22b, whichever of batteries 22b and 22c has a larger SOC, in series with battery 22a to supply power to the drive motor 10. As a result, the SOC adjustment unit 314 supplies power to the drive motor 10 from batteries 22a and 22b, so that, for example, the SOC of battery 22a becomes 90% and the SOC of battery 22b becomes 70%. In other words, batteries 22b and 22c, which are among batteries 22a, 22b, and 22c, are pre-configured with SOCs of 70%. At this time, no power is supplied from battery 22c. Subsequently, the SOC adjustment unit 314 controls the switching unit 24 to connect batteries 22b and 22c, both of which have an SOC of 70%, in parallel, and to connect battery 22a, which has an SOC of 90%, in series with batteries 22b and 22c.

[0044] The SOC adjustment unit 314 releases the series-parallel configuration when the SOC difference between three or more batteries 22 falls below a second threshold. Specifically, the SOC adjustment unit 314 determines whether the SOC difference has fallen below the second threshold by comparing the SOC acquired by the SOC acquisition unit 312 with a second threshold previously stored in the storage unit 32. After releasing the series-parallel configuration, the SOC adjustment unit 314 controls the switching unit 24 to supply power to the drive motor 10 as either a series or parallel connection for the three or more batteries 22. As a result, the vehicle 1 returns from SOC adjustment driving to normal driving.

[0045] (Required voltage acquisition unit) The requested voltage acquisition unit 315 acquires the requested voltage of the drive motor 10 in the series-parallel configuration described above. Specifically, the requested voltage acquisition unit 315 may calculate the requested torque of the drive motor 10 from the amount of depression of the accelerator pedal (not shown) and acquire the inverter voltage required to obtain the calculated requested torque as the requested voltage. The relationship between the requested torque and the requested voltage may be stored in advance in the storage unit 32 so that the requested voltage acquisition unit 315 can refer to it.

[0046] (Voltage control unit) The voltage control unit 316 controls the converter 50, which is equivalent to a voltage conversion unit, to boost or lower the power supplied to the drive motor 10 to the requested voltage acquired by the requested voltage acquisition unit 315. Specifically, when the batteries 22 are connected in series during normal use, if a series-parallel state is established during SOC adjustment, the system voltage will drop below that of normal use. For this reason, the voltage control unit 316 controls the converter 50, which is an example of a voltage conversion unit, via the vehicle control device 60, to boost the power supplied to the drive motor 10 to the requested voltage acquired by the requested voltage acquisition unit 315. On the other hand, when the batteries 22 are connected in parallel during normal use, if a series-parallel state is established during SOC adjustment, the system voltage will rise above that of normal use. For this reason, the voltage control unit 316 controls the converter 50, which is an example of a voltage conversion unit, via the vehicle control device 60, to lower the power supplied to the drive motor 10 to the requested voltage acquired by the requested voltage acquisition unit 315.

[0047] (1-2-3. Example of Battery Control Device Operation) Referring to Figure 7, an example of the operation of the battery control device 30 according to the first embodiment will be explained in accordance with the flowchart.

[0048] For simplicity, the following explanation will use the example of a case where only battery 22a is replaced among the interchangeable batteries 22a, 22b, and 22c. Furthermore, it will be assumed that the State of Charge (SOC) of battery 22a is 100%, the SOC of battery 22b is 80%, and the SOC of battery 22c is 70%. It will also be assumed that during normal operation of vehicle 1, batteries 22a, 22b, and 22c are connected in series. However, this disclosure is not limited to these examples.

[0049] In step S110, the replacement detection unit 311 of the processing unit 31 detects that batteries 22a, 22b, and 22c have been replaced. The process then proceeds to step S111.

[0050] In step S111, the SOC acquisition unit 312 of the processing unit 31 acquires the SOC of batteries 22a, 22b, and 22c, respectively. The SOC acquisition unit 312 may also continuously monitor the SOC at predetermined calculation intervals during the process. The same applies hereafter. After that, the process proceeds to step S112.

[0051] In step S112, the connection state determination unit 313 of the processing unit 31 identifies battery 22a, battery 22b, and battery 22c, whose SOC is equal to or greater than the first threshold, as the first battery 22-1. The connection state determination unit 313 also identifies batteries 22b and 22c, whose SOC is less than the first threshold, as the second battery 22-2. The process then proceeds to step S113.

[0052] In step S113, the connection status determination unit 313 of the processing unit 31 selects a second battery 22-2 from among batteries 22b and 22c to be connected to battery 22a, based on the State of Charge (SOC) of batteries 22b and 22c identified in step S112. In this example, it is assumed that battery 22b is selected by the method described above. The process then proceeds to step S114.

[0053] In step S114, the SOC adjustment unit 314 of the processing unit 31 controls the switching unit 24 to supply power to the drive motor 10 by connecting the battery 22b selected in step S113 in series with the battery 22a. Specifically, referring to Figure 2, the SOC adjustment unit 314 connects switch SW-A, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-B, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-C, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-D, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-E, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-F, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-G, which corresponds to the switching unit 24, to contact b. Furthermore, the SOC adjustment unit 314 connects switch SW-H, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-I, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-J, which corresponds to the switching unit 24, to contact a. In step S114, the goal is to set the SOC of battery 22a to, for example, 90%, and the SOC of battery 22b to, for example, 70%. After that, the process proceeds to step S115.

[0054] In step S114, the requested voltage acquisition unit 315 of the processing unit 31 may acquire the requested voltage of the drive motor 10 using the method described above. The voltage control unit 316 may then control the converter 50, which is an example of a voltage conversion unit, to boost the power to the drive motor 10 to the requested voltage acquired by the requested voltage acquisition unit 315. This makes it possible to suppress the decrease in system voltage caused by configuring a series connection using only batteries 22a and 22b.

[0055] In step S115, the SOC acquisition unit 312 of the processing unit 31 acquires the SOC of batteries 22b and 22c. The process then proceeds to step S116.

[0056] In step S116, the SOC adjustment unit 314 of the processing unit 31 determines whether the SOC difference between the SOC of battery 22b and the SOC of battery 22c, which was acquired in step S115, has fallen below the third threshold. If it is determined that the SOC difference has fallen below the third threshold (step S116: YES), the process proceeds to step S117. On the other hand, if it is not determined that the SOC difference has fallen below the third threshold (step S116: NO), the process returns to step S115. That is, the SOC adjustment by the SOC adjustment unit 314 continues, and the SOC is acquired by the SOC acquisition unit 312 at an appropriate timing.

[0057] In step S117, the SOC adjustment unit 314 of the processing unit 31 controls the switching unit 24 to disconnect the series connection between battery 22a and battery 22b. At the same time, the SOC adjustment unit 314 controls the switching unit 24 to supply power to the drive motor 10 by configuring a series-parallel state in which the connection state of battery 22b and battery 22c is parallel, and the connection state of battery 22a to battery 22b and battery 22c is series. Specifically, referring to Figure 2, the SOC adjustment unit 314 connects switch SW-A, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-B, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-C, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-D, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-E, which corresponds to the switching unit 24, to contact a. Furthermore, the SOC adjustment unit 314 connects switch SW-F, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-G, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-H, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-I, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-J, which corresponds to the switching unit 24, to contact a. In step S117, the goal is to match the SOCs of batteries 22a, 22b, and 22c. The process then proceeds to step S118.

[0058] In step S117, the requested voltage acquisition unit 315 of the processing unit 31 may acquire the requested voltage of the drive motor 10 using the method described above. The voltage control unit 316 of the processing unit 31 may then control the converter 50, which is an example of a voltage conversion unit, to boost the power to the drive motor 10 to the requested voltage acquired by the requested voltage acquisition unit 315. This makes it possible to suppress the decrease in system voltage caused by forming a series-parallel state.

[0059] In step S118, the SOC acquisition unit 312 of the processing unit 31 acquires the SOC of batteries 22a, 22b, and 22c. The process then proceeds to step S119.

[0060] In step S119, the SOC adjustment unit 314 of the processing unit 31 determines whether the SOC differences between battery 22a, battery 22b, and battery 22c, which were acquired in step S118, have all fallen below a second threshold. If it is determined that the SOC differences have fallen below the second threshold (step S119: YES), the process proceeds to step S120. On the other hand, if it is not determined that the SOC differences have fallen below the second threshold (step S119: NO), the process returns to step S118. That is, the SOC adjustment by the SOC adjustment unit 314 continues, and the SOC is acquired by the SOC acquisition unit 312 at an appropriate timing.

[0061] In step S120, the SOC adjustment unit 314 of the processing unit 31 controls the switching unit 24 to supply power to the drive motor 10 by connecting batteries 22a, 22b, and 22c in series after the series-parallel state is released. Specifically, referring to Figure 2, the SOC adjustment unit 314 connects switch SW-A, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-B, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-C, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-D, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-E, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-F, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-G, which corresponds to the switching unit 24, to contact b. Furthermore, the SOC adjustment unit 314 connects switch SW-H, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-I, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-J, which corresponds to the switching unit 24, to contact a. As a result, vehicle 1 returns from SOC adjustment driving to normal driving. After that, the process ends.

[0062] (1-3. Summary) As described above, the processing unit 31 of the battery control device 30 according to the first embodiment identifies one or more first batteries 22-1 from among the three or more batteries 22 whose SOC is equal to or greater than a first threshold. The processing unit 31 also identifies two or more second batteries 22-2 from among the three or more batteries 22 whose SOC is less than the first threshold. The processing unit 31 also controls the switching unit 24 to supply power to the drive motor 10 by configuring a series-parallel state in which the two or more identified second batteries 22-2 are connected in parallel and the one or more first batteries 22-1 connected to the two or more identified second batteries 22-2 are connected in series. The processing unit 31 also controls the switching unit 24 to release the series-parallel state when the SOC difference of the three or more batteries 22 falls below a second threshold.

[0063] In particular, in the first embodiment, when configuring a series-parallel state, the processing unit 31 selects one or more batteries 22 to be connected to one or more first batteries 22-1, selected from the two or more second batteries 22-2 based on the State of Charge (SOC) of the two or more identified second batteries 22-2. The processing unit 31 also controls the switching unit 24 to supply power to the drive motor 10 by connecting the one or more identified first batteries 22-1 and the selected battery 22 in series. Subsequently, when the SOC difference between the two or more second batteries 22-2 falls below a third threshold, the processing unit 31 disconnects the series connection and controls the switching unit 24 to supply power to the drive motor 10 in a series-parallel state.

[0064] According to the first embodiment, there is no need to stop the vehicle 1 after replacing the battery 22, and the relatively fast power consumption by the drive system allows the State of Charge (SOC) of all batteries 22 to be matched. Furthermore, unlike conventional methods, there is no need to switch the series-connected batteries 22 to parallel connections and allow current to flow for a long time from the battery 22 with a high SOC to the battery 22 with a low SOC in order to match the SOC of all batteries 22. As a result, the time required to match the SOC of all batteries 22 can be shortened, and circulating current flowing between batteries 22 can be suppressed.

[0065] <2. Second Embodiment> A second embodiment of this disclosure will now be described. The differences from the first embodiment will be described below.

[0066] (2-1. Example Configuration) Referring to Figure 1, vehicle 1 further comprises on-board auxiliary equipment 70 powered by electricity from battery 22. On-board auxiliary equipment 70 is any low-voltage operating electrical equipment mounted on vehicle 1. On-board auxiliary equipment 70 is electrically connected to battery 22 via a known or any DC-DC converter 80, and is also electrically connected to a low-voltage battery 90. Examples of low-voltage batteries 90 include lead-acid batteries or lithium-ion batteries with a rating of 12V or 24V, but are not particularly limited.

[0067] The switching unit 24 further controls the connection state between at least one battery 22 among the three or more batteries 22 and the on-board auxiliary equipment 70 powered by the power from at least one battery 22. The switching unit 24 can be a switch similar to that used in the first embodiment.

[0068] Referring to Figure 8, an example of the arrangement of the battery 22 and the switching unit 24 will be described. The circuit in the second embodiment further includes a power line L1 connected to the positive terminal of the onboard auxiliary equipment 70 via switch SW-a, which is an example of the switching unit 24, compared to the circuit in the first embodiment. The circuit in the second embodiment further includes a power line L2 connected to the negative terminal of the onboard auxiliary equipment 70 via switch SW-b, which is an example of the switching unit 24, compared to the circuit in the first embodiment. Switches SW-a and SW-b are, for example, single-pole single-throw switching elements, but this disclosure is not limited thereto. In Figure 8, only power lines L1 and L2 between battery b and the onboard auxiliary equipment 70 are shown as power lines for transferring power between the battery 22 and the onboard auxiliary equipment 70. However, as can be easily understood by those skilled in the art, there are also power lines (not shown) that enable the transfer of power between battery a and the onboard auxiliary equipment 70, and power lines (not shown) that enable the transfer of power between battery b and the onboard auxiliary equipment 70.

[0069] Referring to Figure 3, the connection state determination unit 313 and the SOC adjustment unit 314 of the processing unit 31 perform the following processing when configuring the series-parallel state described in the first embodiment. Specifically, the connection state determination unit 313 identifies the battery 22 to be supplied with power to the on-board auxiliary equipment 70 from among the two or more second batteries 22-2 based on the SOC of the two or more second batteries 22-2 identified in the same manner as in the first embodiment, and transmits the identification result to the SOC adjustment unit 314. When the SOC adjustment unit 314 receives the identification result from the connection state determination unit 313, it controls the switching unit 24 to supply power from the identified battery 22 to the on-board auxiliary equipment 70. Furthermore, when the SOC difference of the two or more second batteries 22-2 falls below the third threshold, the SOC adjustment unit 314 terminates the power supply to the on-board auxiliary equipment 70 and controls the switching unit 24 to supply power to the drive motor 10 in the same manner as in the first embodiment by configuring a series-parallel state.

[0070] Here, as an example, suppose that the SOC of battery 22a is 100%, the SOC of battery 22b is 80%, and the SOC of battery 22c is 70%, and the connection state determination unit 313 identifies battery 22a as the first battery 22-1, and batteries 22b and 22c as the second battery 22-2. In this case, the connection state determination unit 313 identifies battery 22b, whichever of batteries 22b and 22c has a larger SOC, as the target for power supply to the on-board auxiliary equipment 70. The SOC adjustment unit 314 consumes the power of battery 22b in the on-board auxiliary equipment 70 until the SOC of battery 22b reaches 70%, and then controls the switching unit 24 to connect battery 22b and battery 22c in parallel, and connect battery 22a in series with batteries 22b and 22c.

[0071] (2-2. Example of Battery Control Device Operation) Referring to Figure 9, an example of the operation of the battery control device 30 according to the second embodiment will be explained in accordance with the flowchart.

[0072] For simplicity, the following explanation will use the example of a case where battery 22a is replaced among the interchangeable batteries 22a, 22b, and 22c. Furthermore, it will be assumed that the State of Charge (SOC) of battery 22a is 100%, the SOC of battery 22b is 80%, and the SOC of battery 22c is 70%. It will also be assumed that during normal operation of vehicle 1, batteries 22a, 22b, and 22c are connected in series. However, this disclosure is not limited to these examples.

[0073] In step S210, the replacement detection unit 311 of the processing unit 31 detects that batteries 22a, 22b, and 22c have been replaced. The process then proceeds to step S211.

[0074] In step S211, the SOC acquisition unit 312 of the processing unit 31 acquires the SOC of batteries 22a, 22b, and 22c, respectively. The SOC acquisition unit 312 may also continuously monitor the SOC at predetermined calculation intervals during the process. The same applies hereafter. After that, the process proceeds to step S212.

[0075] In step S212, the connection state determination unit 313 of the processing unit 31 identifies battery 22a, which has a State of Charge (SOC) equal to or greater than the first threshold, as the first battery 22-1. The connection state determination unit 313 also identifies batteries b22 and 22c, which have a State of Charge (SOC) less than the first threshold, as the second battery 22-2. The process then proceeds to step S213.

[0076] In step S213, the connection state determination unit 313 of the processing unit 31 selects a second battery 22-2 from among batteries 22b and 22c to be used to supply power to the onboard auxiliary equipment 70, based on the State of Charge (SOC) of batteries 22b and 22c identified in step S212. In this example, it is assumed that battery 22b is selected by the method described above. The process then proceeds to step S214.

[0077] In step S214, the SOC adjustment unit 314 of the processing unit 31 controls the switching unit 24 to supply power from the battery 22b selected in step S213 to the on-board auxiliary equipment 70. Specifically, referring to Figure 8, the SOC adjustment unit 314 controls switches SW-a and SW-b, which correspond to the switching unit 24, to be turned ON. Note that "ON" means an energized state that enables the exchange of power between the battery b and the on-board auxiliary equipment 70. The SOC adjustment unit 314 also connects switch SW-A, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-B, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-C, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-D, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-E, which corresponds to the switching unit 24, to contact a. Furthermore, the SOC adjustment unit 314 connects switch SW-F, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-G, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-H, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-I, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-J, which corresponds to the switching unit 24, to contact a. At this time, the vehicle 1 is stopped, and no power is supplied to the drive motor 10, which is different from the first embodiment. Also, it is preferable that batteries 22a and 22c, which are not connected to the on-board auxiliary equipment 70, are connected in series from the viewpoint of avoiding circulating current. In step S214, the goal is to set the SOC of battery 22b to, for example, 70%. After that, the process proceeds to step S215.

[0078] In step S215, the SOC acquisition unit 312 of the processing unit 31 acquires the SOC of the battery 22b. The process then proceeds to step S116.

[0079] In step S216, the SOC adjustment unit 314 of the processing unit 31 determines whether the difference in SOC between the SOC of battery 22b acquired in step S215 and the SOC of battery 22c acquired in step S211 is less than the third threshold. If it is determined that the SOC difference is less than the third threshold (step S216: YES), the process proceeds to step S217. On the other hand, if it is not determined that the SOC difference is less than the third threshold (step S216: NO), the process returns to step S215. That is, power supply to the onboard auxiliary equipment 70 continues, and the SOC is acquired by the SOC acquisition unit 312 at an appropriate timing.

[0080] In step S217, the SOC adjustment unit 314 of the processing unit 31 controls the switching unit 24 to terminate the power supply to the onboard auxiliary equipment 70. Specifically, the SOC adjustment unit 314 controls switches SW-a and SW-b, which correspond to the switching unit 24, to turn off. At the same time, the SOC adjustment unit 314 controls the switching unit 24 to supply power to the drive motor 10 by configuring a series-parallel state in which the connection state of batteries 22b and 22c is in parallel, and the connection state of battery 22a to batteries 22b and 22c is in series. Specifically, referring to Figure 8, the SOC adjustment unit 314 connects switch SW-A, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-B, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-C, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-D, which corresponds to the switching unit 24, to contact a. Furthermore, the SOC adjustment unit 314 connects switch SW-E, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-F, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-G, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-H, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-I, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-J, which corresponds to the switching unit 24, to contact a. In step S217, the goal is to match the SOCs of batteries 22a, 22b, and 22c. After that, the process proceeds to step S218.

[0081] In step S217, the requested voltage acquisition unit 315 of the processing unit 31 may acquire the requested voltage of the drive motor 10 using the method described above. The voltage control unit 316 of the processing unit 31 may then control the converter 50, which is an example of a voltage conversion unit, to boost the power to the drive motor 10 to the requested voltage acquired by the requested voltage acquisition unit 315. This makes it possible to suppress the decrease in system voltage caused by forming a series-parallel state.

[0082] In step S218, the SOC acquisition unit 312 of the processing unit 31 acquires the SOC of batteries 22a, 22b, and 22c. The process then proceeds to step S219.

[0083] In step S219, the SOC adjustment unit 314 of the processing unit 31 determines whether the SOC differences between battery 22a, battery 22b, and battery 22c, which were acquired in step S218, have all fallen below a second threshold. If it is determined that the SOC differences have fallen below the second threshold (step S219: YES), the process proceeds to step S220. On the other hand, if it is not determined that the SOC differences have fallen below the second threshold (step S219: NO), the process returns to step S218. That is, the SOC adjustment by the SOC adjustment unit 314 continues, and the SOC is acquired by the SOC acquisition unit 312 at an appropriate timing.

[0084] In step S220, the SOC adjustment unit 314 of the processing unit 31 controls the switching unit 24 to supply power to the drive motor 10 by connecting batteries 22a, 22b, and 22c in series after the series-parallel state is released. Specifically, referring to Figure 8, the SOC adjustment unit 314 connects switch SW-A, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-B, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-C, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-D, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-E, which corresponds to the switching unit 24, to contact a. The SOC adjustment unit 314 also connects switch SW-F, which corresponds to the switching unit 24, to contact b. The SOC adjustment unit 314 also connects switch SW-G, which corresponds to the switching unit 24, to contact b. Furthermore, the SOC adjustment unit 314 connects switch SW-H, which corresponds to the switching unit 24, to contact b. Also, the SOC adjustment unit 314 connects switch SW-I, which corresponds to the switching unit 24, to contact a. Also, the SOC adjustment unit 314 connects switch SW-J, which corresponds to the switching unit 24, to contact a. Note that switches SW-a and SW-b remain in the off position. As a result, vehicle 1 returns to normal operation. The process then ends.

[0085] (2-3. Summary) As described above, the processing unit 31 of the battery control device 30 according to the second embodiment identifies one or more first batteries 22-1 from among the three or more batteries 22 whose SOC is equal to or greater than a first threshold. The processing unit 31 also identifies two or more second batteries 22-2 from among the three or more batteries 22 whose SOC is less than the first threshold. The processing unit 31 also controls the switching unit 24 to supply power to the drive motor 10 by configuring a series-parallel state in which the connection state of the two or more identified second batteries 22-2 to be in parallel, and the connection state of one or more first batteries 22-1 to the two or more identified second batteries 22-2 to be in series. The processing unit 31 also controls the switching unit 24 to release the series-parallel state when the SOC difference of the three or more batteries 22 falls below a second threshold.

[0086] In particular, in the second embodiment, the switching unit 24 further controls the connection state between at least one battery 22 out of three or more batteries 22 and the on-board auxiliary equipment 70 driven by power from at least one battery 22. The processing unit 31 also identifies the battery 22 to be used to supply power to the on-board auxiliary equipment 70 from among the two or more second batteries 22-2 based on the State of Charge (SOC) of the two or more identified second batteries 22-2 when configuring the series-parallel state. The processing unit 31 also controls the switching unit 24 to supply power from the identified battery 22 to the on-board auxiliary equipment 70. Subsequently, the processing unit 31 controls the switching unit 24 to terminate the power supply to the on-board auxiliary equipment 70 and to supply power to the drive motor 10 in a series-parallel state when the SOC difference between the two or more second batteries 22-2 falls below a third threshold.

[0087] According to the second embodiment, although the vehicle 1 needs to be stopped while the on-board auxiliary equipment 70 consumes power, the auxiliary equipment system consumes power more slowly than the drive system, thus suppressing the degradation of the battery 22 associated with SOC adjustment. Furthermore, unlike conventional methods, it is not necessary to switch the series-connected batteries 22 to parallel connections and allow current to flow for a long time from the battery 22 with a high SOC to the battery 22 with a low SOC in order to match the SOC of all batteries 22. As a result, the time required to match the SOC of all batteries 22 can be shortened, and circulating current flowing between batteries 22 can be suppressed.

[0088] While preferred embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the present disclosure is not limited to such examples. It is clear to any person with ordinary skill in the art to which the present disclosure belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also be understood to fall within the technical scope of the present disclosure. For example, the functions, etc., included in each component or step, etc., can be rearranged in a logically consistent manner, and multiple components or steps, etc., can be combined into one or divided into two.

[0089] (3. A variation of the first example) As a first modification, the SOC adjustment unit 314 of the processing unit 31 may control the switching unit 24 to connect at least one of the one or more first batteries 22-1 and at least one of the two or more second batteries 22-2 to a parallel connection when configuring the series-parallel state described above. Alternatively, the SOC adjustment unit 314 may then control the switching unit 24 to disconnect the parallel connection and configure a series-parallel state to supply power to the drive motor 10 when the SOC difference between the two or more second batteries 22-2 falls below the third threshold.

[0090] Here, as an example, suppose that the SOC of battery 22a is 100%, the SOC of battery 22b is 80%, and the SOC of battery 22c is 70%, and that battery 22a is identified as the first battery 22-1, and batteries 22b and 22c are identified as the second batteries 22-2. In this case, the SOC adjustment unit 314 controls the switching unit 24 to connect battery 22a and battery 22c, whichever of batteries 22b and 22c has the smaller SOC, in parallel. After that, the SOC adjustment unit 314 supplies power from battery 22a to battery 22c until the SOC of battery 22c reaches 80%. At this time, vehicle 1 is stationary, and no power is supplied to the drive motor 10. Subsequently, the SOC adjustment unit 314 controls the switching unit 24 to connect batteries 22b and 22c in parallel, and to connect battery 22a in series with batteries 22b and 22c. At this time, power is supplied to the drive motor 10, and vehicle 1 performs SOC adjustment driving.

[0091] According to the first modification, although the vehicle 1 needs to be stopped while the batteries are connected in parallel, power consumption can be reduced compared to the first embodiment, thus suppressing the degradation of the battery 22 associated with SOC adjustment. Furthermore, unlike conventional methods, it is not necessary to switch the series-connected batteries 22 to parallel connections and flow current from the battery 22 with a high SOC to the battery 22 with a low SOC for about an hour to match the SOC of all batteries 22. In other words, it is not necessary to match the SOC of all batteries 22; for example, it is sufficient to flow current from battery 22a to battery 22c until the SOC of battery 22c drops from 80% to 70%, and thereafter SOC adjustment is performed using the drive system. Therefore, the time required to match the SOC of all batteries 22 can be shortened.

[0092] In the first modified example, the SOC adjustment unit 314 may, when connected in parallel, for example, when the current from battery 22a to battery 22c approaches a state of equilibrium and becomes difficult to flow, control the switching unit 24 to supply power from battery 22b to the on-board auxiliary equipment 70 in the same manner as in the second embodiment. This makes it possible to bring the SOCs of batteries 22b and 22c closer together, thereby enabling the series-parallel configuration described above.

[0093] (4. Second variation) As a second variation, a configuration combining the first and second embodiments is also possible. For example, suppose that the SOC of battery 22a is 100%, the SOC of battery 22b is 80%, and the SOC of battery 22c is 70%. In this case, batteries 22a and 22b are connected in series to supply power to the drive motor 10 in the same manner as in the first embodiment, while power from battery 22c is supplied to the on-board auxiliary equipment 70 in the same manner as in the second embodiment. When the SOCs of batteries 22b and 22c match, the above-described series-parallel configuration may be achieved.

[0094] (5. Third variation) As a third modification, when the processing unit 31 of the battery control device 30 detects that the battery 22 has been replaced by the method described above, it may perform a process to allow the driver of the vehicle 1 to choose whether to (i) perform SOC adjustment as in the first embodiment or (ii) perform SOC adjustment as in the second embodiment. Specifically, the processing unit 31 of the battery control device 30 may ask the driver about (i) and (ii) above by displaying text, images, or outputting audio, for example, via a car navigation device (not shown) installed in the vehicle 1, and select the SOC adjustment of (i) or (ii) based on the driver's response. The question may also include, in place of or in addition to (i) or (ii), a question asking the driver whether to perform SOC adjustment as in the first or second modification.

[0095] (6. Other) The technology of this disclosure can also be realized as a vehicle 1 equipped with a battery control device 30 according to the above-described embodiment or modification, a battery control method executed by the battery control device 30 according to the above-described embodiment or modification, a computer program that causes a computer to function as the battery control device 30 according to the above-described embodiment or modification, and a non-temporary tangible recording medium on which the computer program is recorded. [Explanation of Symbols]

[0096] 1: Vehicle, 10: Drive motor, 20: Battery system, 22: Battery, 22-1: First battery, 22-2: Second battery, 24: Switching unit, 30: Battery control device, 31: Processing unit, 311: Replacement detection unit, 312: SOC acquisition unit, 313: Connection status determination unit, 314: SOC adjustment unit, 315: Requested voltage acquisition unit, 316: Voltage control unit, 32: Memory unit

Claims

1. A battery control device applied to a battery system comprising three or more batteries that supply power to a vehicle's drive motor, and a switching unit that switches the connection state of the three or more batteries, It comprises one or more processors and one or more memories connected to the one or more processors in a communicative manner, The aforementioned one or more processors Of the three or more batteries mentioned above, one or more first batteries whose SOC is equal to or greater than a first threshold are identified. Of the three or more batteries, identify two or more second batteries whose SOC is less than the first threshold, The switching unit is controlled to supply power to the drive motor by configuring a series-parallel configuration in which the connections between the two or more specified second batteries are in parallel, and the connections between the one or more specified first batteries and the two or more specified second batteries are in series. The switching unit is controlled to release the series-parallel state when the SOC difference of the three or more batteries falls below a second threshold. Battery control device.

2. The aforementioned one or more processors In configuring the aforementioned series-parallel state, Based on the State of Control (SOC) of the two or more identified second batteries, a battery is selected from among the two or more second batteries to be connected to the one or more identified first batteries. The switching unit is controlled to connect one or more of the identified first batteries and the selected battery in series to supply power to the drive motor. Subsequently, when the SOC difference between the two or more second batteries falls below the third threshold, the series connection is released, and the switching unit is controlled to configure the series-parallel state and supply power to the drive motor. The battery control device according to claim 1.

3. The switching unit further controls the connection state between at least one of the three or more batteries and an on-board auxiliary device powered by the power from that at least one battery. The aforementioned one or more processors In configuring the aforementioned series-parallel state, Based on the State of Control (SOC) of the two or more second batteries identified, the battery to be used to supply power to the on-board auxiliary equipment is identified from among the two or more second batteries. The switching unit is controlled to supply power from the identified battery to the onboard auxiliary equipment. Subsequently, when the SOC difference between the two or more second batteries falls below the third threshold, the switching unit is controlled to terminate the power supply to the on-board auxiliary equipment and to supply the power to the drive motor in the series-parallel configuration. The battery control device according to claim 1.

4. The aforementioned one or more processors In configuring the series-parallel configuration, the switching unit is controlled to connect at least one of the one or more first batteries to a parallel connection with at least one of the two or more second batteries. Subsequently, when the SOC difference between the two or more second batteries falls below the third threshold, the parallel connection is released, and the switching unit is controlled to configure the series-parallel state and supply power to the drive motor. The battery control device according to claim 1.

5. The battery system further comprises a voltage conversion unit that boosts or depresses the power of the three or more batteries. In the series-parallel state, the one or more processors The required voltage of the aforementioned drive motor is obtained, The voltage conversion unit is controlled to increase or decrease the power supplied to the drive motor to the acquired requested voltage. The battery control device according to any one of claims 1 to 4.

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