Battery capacity adjustment device and battery capacity adjustment method

Abstract

A battery capacity adjustment device (18) comprises: a battery capacity adjustment circuit (20) that adjusts the capacities of a plurality of batteries (b1-b4), which are connected in series and which constitute a battery pack (2), by transferring charge between the plurality of batteries (b1-b4); a monitoring unit (22) that acquires the temperatures at a plurality of positions in the battery pack (2); and a control unit (24) that controls the battery capacity adjustment circuit (20) so as to reduce the current flowing through a battery of interest which is included in the plurality of batteries (b1-b4) and which corresponds to a position at the highest temperature among the plurality of positions.

Description

Battery capacity adjustment device and battery capacity adjustment method

[0001] The present disclosure relates to a battery capacity adjustment device and a battery capacity adjustment method for adjusting the capacity of a plurality of series-connected batteries that constitute a battery pack.

[0002] Patent Document 1 discloses a technology that enables a power supply system including a plurality of storage batteries to flexibly adjust the temperature of the storage batteries while energizing the storage batteries and a load.

[0003] JP 2025-012900 A

[0004] Batteries such as lithium-ion batteries deteriorate (specifically, their capacity decreases) when used in high ambient temperatures. As battery deterioration progresses, the internal resistance of the battery increases, generating heat due to Joule heat, which further increases the battery temperature and accelerates deterioration.

[0005] Therefore, the present disclosure provides a battery capacity adjustment device and the like that can suppress the rate of deterioration of a battery that may be prone to accelerated deterioration.

[0006] The battery capacity adjustment device according to the present disclosure includes a battery capacity adjustment circuit that adjusts the capacity of a plurality of series-connected batteries that constitute a battery pack by transferring charge between the plurality of batteries, an acquisition unit that acquires temperatures at a plurality of positions in the battery pack, and a control unit that controls the battery capacity adjustment circuit to reduce the current flowing to a target battery included in the plurality of batteries, the target battery corresponding to the position with the highest temperature among the plurality of positions.

[0007] The battery capacity adjustment method according to the present disclosure is a method executed by a battery capacity adjustment device, and includes an acquisition step of acquiring temperatures at multiple positions in a battery pack composed of multiple batteries connected in series, and an adjustment step of adjusting the capacity of the multiple batteries so as to reduce the current flowing through a target battery included in the multiple batteries, the target battery corresponding to the position with the highest temperature among the multiple positions.

[0008] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0009] According to the battery capacity adjustment device and the like according to one aspect of the present disclosure, the rate of battery deterioration can be suppressed.

[0010] FIG. 1 is a configuration diagram showing an example of a battery capacity adjustment device according to an embodiment. FIG. 2 is a diagram for explaining a plurality of positions at which temperatures in a battery pack are acquired. FIG. 3 is a circuit diagram showing an example of a battery capacity adjustment circuit according to an embodiment. FIG. 4 is a flowchart showing an example of the operation of a battery capacity adjustment device according to an embodiment. FIG. 5 is a diagram for explaining the operation of a battery capacity adjustment device according to an embodiment during charging. FIG. 6 is a diagram for explaining the operation of a battery capacity adjustment device according to an embodiment during discharging. FIG. 7 is a flowchart showing an example of a battery capacity adjustment method according to another embodiment.

[0011] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0012] The embodiments described below are all comprehensive or specific examples, and the numerical values, shapes, materials, components, arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0013] (Embodiment) Hereinafter, a battery capacity adjustment device according to an embodiment will be described.

[0014] 1 is a configuration diagram showing an example of a battery capacity adjustment device 18 according to an embodiment. In addition to the battery capacity adjustment device 18, Fig. 1 also shows a battery pack 2, a load 4, an external power supply 8, relays 6A, 6B, 14A, and 14B, and an ammeter 16.

[0015] The battery pack 2 has multiple batteries connected in series. Here, batteries b1 to b4 are shown as the multiple batteries that make up the battery pack 2. The number of batteries is not limited to four, and may be two, three, five or more. Each of the batteries b1 to b4 is a secondary battery that can be charged and discharged, such as a lead-acid battery or a lithium-ion battery.

[0016] The load 4 is a device that operates using the power supplied by the battery pack 2, and is, for example, an actuator, a motor, or a control device.

[0017] The external power supply 8 is a power supply that supplies power to the battery pack 2. The external power supply 8 includes a conversion unit 12 that converts AC power from an AC power supply 10 into DC power. The conversion unit 12 is, for example, an alternating current (AC) / direct current (DC) converter.

[0018] The relays 14A and 14B are controlled to the ON state when power is supplied from the external power source 8 to the battery pack 2, that is, when the battery pack 2 is being charged. The relays 6A and 6B are controlled to the ON state when power is supplied from the battery pack 2 to the load 4, that is, when the battery pack 2 is being discharged.

[0019] The battery capacity adjustment device 18 is a device that adjusts the capacity of the series-connected batteries b1 to b4 that make up the battery pack 2. The battery capacity adjustment device 18 adjusts the capacity of the batteries b1 to b4 by charging and discharging the batteries b1 to b4 so as to eliminate the temperature difference between the batteries b1 to b4.

[0020] The battery capacity adjustment device 18 includes a battery capacity adjustment circuit 20 , a monitoring unit 22 , and a control unit 24 .

[0021] The monitoring unit 22 acquires temperatures at multiple positions in the battery pack 2. The monitoring unit 22 is an example of an acquisition unit. For example, the monitoring unit 22 acquires temperatures at multiple positions using a temperature measurement sensor such as a thermocouple. The monitoring unit 22 also monitors the charge (i.e., current) moving between the batteries b1 to b4 when adjusting the capacity of the batteries b1 to b4. An example of multiple positions at which temperatures are acquired by the monitoring unit 22 will now be described with reference to FIG. 2.

[0022] 2 is a diagram illustrating a plurality of positions at which the temperature is acquired in the battery pack 2. In order to facilitate the explanation of the plurality of positions, FIG. 2 illustrates an example in which the battery pack 2 is composed of 14 batteries.

[0023] As shown in FIG. 2 , the multiple positions may be positions on the pack of the battery pack 2. For example, the monitoring unit 22 acquires temperatures at positions (measurement points) A to F on the battery pack 2. For example, it is pre-assigned that the batteries corresponding to position A are batteries 1-1 and 1-2, the batteries corresponding to position B are batteries 2-1 and 2-2, the batteries corresponding to position C are batteries 3-1, 3-2, and 3-3, the batteries corresponding to position D are batteries 4-1 and 4-2, the batteries corresponding to position E are batteries 5-1, 5-2, and 5-3, and the batteries corresponding to position F are batteries 6-1 and 6-2. For example, as shown in FIG. 2 , if a high-temperature source (e.g., direct sunlight or an inverter) is located near position A, the temperature of the environment surrounding batteries 1-1 and 1-2 will rise, and the acquired temperature at position A will rise, indicating that the temperatures of batteries 1-1 and 1-2 will also rise. For example, if the acquired temperature at position F is high, it indicates that batteries 6-1 and 6-2 are generating heat.

[0024] In this way, it is not necessary to directly measure the temperature of each of the multiple batteries constituting the battery pack 2, but it is also possible to measure the temperature on the pack of the battery pack 2. By measuring the temperature on the pack of the battery pack 2, it is possible to measure the temperature of the environment surrounding the multiple batteries.

[0025] The plurality of positions may be positions on a plurality of batteries. For example, in the case of the battery pack 2 shown in FIG. 2, the plurality of positions may be positions on each of the batteries 1-1 to 6-2. In this manner, the temperature of each of the plurality of batteries constituting the battery pack 2 may be measured directly.

[0026] 1, the battery capacity adjustment circuit 20 adjusts the capacity of the series-connected batteries b1 to b4 that make up the battery pack 2 by transferring charge between the batteries b1 to b4. Here, the details of the battery capacity adjustment circuit 20 will be described with reference to FIG.

[0027] FIG. 3 is a circuit diagram showing an example of the battery capacity adjustment circuit 20 according to the embodiment.

[0028] For example, the battery capacity adjustment circuit 20 includes changeover switches SWa to SWi and an isolated DC / DC converter 36 .

[0029] The changeover switches SWa to SWi are provided between the isolated DC / DC converter 36 and the batteries b1 to b4. The changeover switches SWa to SWi are controlled by the control unit 24. The changeover switches SWa to SWi are, for example, semiconductor switches. The number of changeover switches included in the battery capacity adjustment circuit 20 increases or decreases depending on the number of batteries that make up the battery pack 2.

[0030] For example, when adjusting the capacity of battery b3, the changeover switches SWb, SWc, SWg, and SWh are controlled when batteries b1 to b4 are being discharged or charged.

[0031] The isolated DC / DC converter 36 is a bidirectional DC / DC converter that boosts DC power input from any of batteries b1 to b4 to DC power suitable for charging the battery pack 2 and outputs it to the battery pack 2, and also reduces DC power input from the battery pack 2 to DC power suitable for charging any of batteries b1 to b4 and outputs it to that battery. Note that a capacitor or an independent power supply may be connected to the isolated DC / DC converter 36. In this case, the isolated DC / DC converter 36 may boost the DC power input from any of batteries b1 to b4 to DC power suitable for charging the capacitor or power supply and output it to that capacitor or power supply, or may reduce the DC power input from the capacitor or power supply to DC power suitable for charging any of batteries b1 to b4 and output it to that battery.

[0032] A non-insulated DC / DC converter may be provided instead of the isolated DC / DC converter 36. A DC / DC converter may be provided for each of the batteries b1 to b4, or DC / DC converters corresponding to two or more batteries may be controlled to simultaneously adjust the capacities of the two or more batteries.

[0033] The control unit 24 controls the battery capacity adjustment circuit 20 to reduce the current flowing through the target battery, which is one of the batteries b1 to b4 and corresponds to the position with the highest temperature among multiple positions in the battery pack 2.

[0034] The target battery at the highest temperature among multiple positions in the battery pack 2 is at risk of accelerated deterioration. Therefore, by reducing the current flowing through the target battery and suppressing the charge / discharge operation of the target battery, heat generation due to Joule heat in the target battery can be suppressed and the temperature of each battery can be equalized. Therefore, the rate of deterioration of batteries at risk of accelerated deterioration can be suppressed. Furthermore, by equalizing the temperature of each battery, the deterioration of each battery also tends to be equalized, making it easier to equalize the remaining capacity of each battery.

[0035] 2, when the temperature at position A is the highest among the acquired temperatures at positions A to F, the control unit 24 controls the battery capacity adjustment circuit 20 to reduce the current flowing through the target batteries 1-1 and 1-2. By reducing the current flowing through the batteries 1-1 and 1-2, which are at risk of accelerating deterioration due to high ambient temperatures, the rate of deterioration of the batteries 1-1 and 1-2 can be suppressed.

[0036] Furthermore, it is not necessary to measure the temperature of each of the multiple batteries one-to-one. As shown in FIG. 2, the temperature may be measured at positions corresponding to two or more batteries on the pack of the assembled battery 2. As shown in FIG. 3, when the battery capacity adjustment device 18 has only one isolated DC / DC converter 36 and there are two or more target batteries, the degradation rate of the two or more batteries can be suppressed evenly by performing control to reduce the flow of current for each of the two or more target batteries one by one in turn. For example, when there are two target batteries, the control to reduce the flow of current is performed alternately for each of the two batteries. Furthermore, when the battery capacity adjustment device 18 has a DC / DC converter for each of the multiple batteries, the degradation rate of the two or more batteries can be suppressed by performing control to reduce the flow of current for each of the two or more batteries simultaneously.

[0037] If the multiple positions are positions on multiple batteries, and the temperature at the position of battery 1-1 is the highest among the acquired temperatures at the positions of batteries 1-1 to 6-2, the control unit 24 controls the battery capacity adjustment circuit 20 to reduce the current flowing to battery 1-1 as the target battery. By directly measuring the temperatures of each of the multiple batteries, it is possible to identify the battery with a high temperature, and by reducing the current flowing to the battery with a high temperature, it is possible to suppress an increase in the internal resistance of that battery and thereby suppress the rate of deterioration of that battery.

[0038] The control unit 24 controls the switches of the battery capacity adjustment circuit 20 and the isolated DC / DC converter 36 to transfer charge between the multiple batteries and reduce the current flowing through the target battery. Details will be explained later with reference to Figures 5A and 5B.

[0039] The control unit 24 is a computer including a processor and a memory. The memory may be a read-only memory (ROM) or a random access memory (RAM), and may store programs to be executed by the processor. The control unit 24 is realized by a processor that executes programs stored in the memory. For example, the control unit 24 may be a microcomputer.

[0040] Next, the operation of the battery capacity adjustment device 18 (specifically, the control unit 24) will be described in detail with reference to FIG.

[0041] 4 is a flowchart showing an example of the operation of the battery capacity adjustment device 18 according to the embodiment. The process shown in FIG. 4 starts when charging or discharging of the battery pack 2 starts.

[0042] First, the control unit 24 acquires current polarity information indicating whether the battery pack 2 is being charged or discharged (step S11). For example, the control unit 24 may acquire the current polarity information from a higher-level system, or may acquire the current polarity information based on the polarity of the current measured by the ammeter 16 that measures the current flowing through the battery pack 2.

[0043] Next, the control unit 24 measures the temperatures at multiple positions in the battery pack 2 via the monitoring unit 22, and stores the highest temperature among the temperatures at the multiple positions and the cell number of the battery corresponding to that position, as well as the lowest temperature among the temperatures at the multiple positions and the cell number of the battery corresponding to that position (step S12). As described above, since a corresponding battery is assigned to each position in advance, these cell numbers can be stored.

[0044] Next, the control unit 24 determines whether or not it is necessary to adjust the capacity, in other words, whether or not it is necessary to control the target battery to reduce the current flowing therethrough (step S13).

[0045] For example, when the multiple positions in the battery pack 2 include two positions where the temperature difference is equal to or greater than a predetermined temperature difference threshold, the control unit 24 controls the battery capacity adjustment circuit 20 to reduce the current flowing through the target battery. For example, when the difference between the maximum temperature and the minimum temperature is equal to or greater than a predetermined temperature difference threshold, the control unit 24 determines that control to reduce the current flowing through the target battery is necessary. When the multiple positions in the battery pack 2 include two positions where the temperature difference is equal to or greater than a predetermined temperature difference threshold, the temperature at the position corresponding to the target battery (i.e., the position with the highest temperature) is higher than the temperatures at the other positions, which may accelerate deterioration of the target battery. Therefore, in such a case, the rate of deterioration of the target battery can be effectively suppressed by initiating control to reduce the current flowing through the target battery.

[0046] The control unit 24 may control the battery capacity adjustment circuit 20 to reduce the current flowing through the target battery when the lowest temperature among the temperatures at multiple locations is equal to or greater than a predetermined temperature threshold. In other words, even if the multiple locations in the battery pack 2 do not include two locations where the temperature difference is equal to or greater than the predetermined temperature difference threshold, control may be performed to reduce the current flowing through the target battery when the minimum temperature is equal to or greater than the predetermined temperature threshold. When the lowest temperature among the multiple locations in the battery pack 2 is equal to or greater than the predetermined temperature threshold, the temperature at multiple locations in the battery pack 2 is generally high, which may accelerate deterioration of the target battery. Therefore, in such a case, the rate of deterioration of the target battery can be effectively suppressed by initiating control to reduce the current flowing through the target battery.

[0047] At this time, the control unit 24 may also control the battery capacity adjustment circuit 20 to reduce the current flowing through each of the batteries other than the target battery. Because the temperature is generally high at multiple locations in the battery pack 2, the degradation rate of all batteries, including the target battery, can be reduced. If the battery capacity adjustment device 18 has only one isolated DC / DC converter 36, the degradation rate of batteries b1 to b4 can be uniformly reduced by sequentially controlling each of batteries b1 to b4 to reduce the current flow. If the battery capacity adjustment device 18 has a DC / DC converter for each of batteries b1 to b4, the degradation rate of batteries b1 to b4 can be simultaneously reduced by simultaneously controlling each of batteries b1 to b4 to reduce the current flow.

[0048] If the control unit 24 determines that control to reduce the current flowing through the target battery is not necessary (No in step S13), the process is stopped.

[0049] If the control unit 24 determines that control to reduce the current flowing to the target battery is necessary (Yes in step S13), it determines whether the battery pack 2 is being charged or discharged based on the current polarity information (step S14).

[0050] When the battery pack 2 is being charged ("Charge" in step S14), the control unit 24 causes the isolated DC / DC converter 36 to perform a boost operation (step S15). The operation of the control unit 24 when the battery pack 2 is being charged will be described with reference to FIG. 5A.

[0051] FIG. 5A is a diagram for explaining the operation of the battery capacity adjustment device 18 (specifically, the control unit 24) during charging according to the embodiment.

[0052] For example, if the target battery is battery b1, the control unit 24 controls the changeover switches SWb, SWc, SWe, and SWf to the on state, causing the isolated DC / DC converter 36 to perform a boost operation. This reduces the charging current that charges battery b1, and the charging current flows to the isolated DC / DC converter 36, where it is boosted and returned to the battery pack 2. This makes it possible to reduce the current flowing to battery b1.

[0053] 4, when the battery pack 2 is being discharged ("Discharge" in step S14), the control unit 24 causes the isolated DC / DC converter 36 to perform a voltage step-down operation (step S16). The operation of the control unit 24 when the battery pack 2 is being discharged will be described with reference to FIG. 5B.

[0054] FIG. 5B is a diagram for explaining the operation of the battery capacity adjustment device 18 (specifically, the control unit 24) during discharging according to the embodiment.

[0055] For example, if the target battery is battery b1, the control unit 24 controls the changeover switches SWb, SWc, SWe, and SWf to the on state, causing the isolated DC / DC converter 36 to perform a voltage step-down operation. This reduces the discharge current discharged from battery b1, and to compensate for this discharge current, a current flows from the battery pack 2 to the isolated DC / DC converter 36, is stepped down by the isolated DC / DC converter 36, and is output from the positive terminal side of battery b1. This makes it possible to reduce the current flowing to battery b1.

[0056] The process from step S11 is repeated until step S13 returns No, that is, until capacity adjustment is no longer necessary.

[0057] For example, the monitoring unit 22 may acquire temperatures at multiple positions in the battery pack 2 after the start of discharging or charging batteries b1 to b4, and the control unit 24 may sequentially determine a target battery based on the temperatures at the multiple positions acquired after the start of discharging or charging batteries b1 to b4, and control the battery capacity adjustment circuit 20 to reduce the current flowing through the sequentially determined target battery after the start of discharging or charging batteries b1 to b4. That is, as shown in FIG. 4 , the process from step S11 to step S16 may be repeated, and in the repetition, temperatures at multiple positions in the battery pack 2 may be acquired sequentially, and the battery capacity adjustment circuit 20 may be controlled based on the most recent acquired temperature. After the start of discharging or charging batteries b1 to b4, the position with the highest temperature among the multiple positions may change. In such a case, the target battery to be controlled to reduce the flowing current may be switched.

[0058] The monitoring unit 22 may acquire temperatures at multiple positions in the battery pack 2 before the start of discharging or charging batteries b1 to b4, and the control unit 24 may determine a target battery based on the temperatures at the multiple positions acquired before the start of discharging or charging batteries b1 to b4, and after the start of discharging or charging batteries b1 to b4, control the battery capacity adjustment circuit 20 to reduce the current flowing through the target battery determined before the start of discharging or charging batteries b1 to b4. In other words, the target battery for which control to reduce the current flowing through batteries b1 to b4 after the start of discharging or charging batteries b1 to b4 may be fixed to the target battery determined based on the temperature before the start of discharging or charging batteries b1 to b4. For example, the battery pack 2 may be installed in an environment where a specific position in the battery pack 2 is likely to be exposed to direct sunlight or adjacent to a high-temperature source, making it prone to temperature increases. In such a case, since the temperature at the specific location rises before the discharge or charging of batteries b1 to b4 starts, as described above, the target battery may be determined before the discharge or charging of batteries b1 to b4 starts, and after the discharge or charging of batteries b1 to b4 starts, the target battery for the control to reduce the flowing current may be fixed to the target battery determined before the discharge or charging of batteries b1 to b4 starts. This eliminates the need to switch the target battery for the control to reduce the flowing current, and reduces the processing load.

[0059] (Other Embodiments) As described above, the embodiments have been described as examples of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. For example, the following modifications are also included in one embodiment of the present disclosure.

[0060] For example, the present disclosure can be realized not only as a battery capacity adjustment device 18, but also as a battery capacity adjustment method including steps (processing) performed by components that make up the battery capacity adjustment device 18 (e.g., a monitoring unit 22 and a control unit 24).

[0061] FIG. 6 is a flowchart showing an example of a battery capacity adjustment method according to another embodiment.

[0062] The battery capacity adjustment method is a method executed by the battery capacity adjustment device 18, and includes, as shown in FIG. 6 , an acquisition step (step S101) of acquiring temperatures at multiple positions in a battery pack composed of multiple batteries connected in series, and an adjustment step (step S102) of adjusting the capacities of the multiple batteries so as to reduce the current flowing through a target battery included in the multiple batteries, the target battery corresponding to the position with the highest temperature among the multiple positions.

[0063] For example, the present disclosure can be realized as a program for causing a computer (processor) to execute steps included in the battery capacity adjustment method. Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

[0064] For example, when the present disclosure is realized as a program (software), each step is performed by running the program using hardware resources such as a computer's CPU, memory, input / output circuits, etc. In other words, each step is performed by the CPU acquiring data from memory or input / output circuits, etc., performing calculations, and outputting the calculation results to memory or input / output circuits, etc.

[0065] In the above embodiment, each component included in the battery capacity adjustment device 18 may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0066] Some or all of the functions of the battery capacity adjustment device 18 according to the above embodiment are typically realized as an LSI, which is an integrated circuit. These may be individually integrated into single chips, or some or all of them may be integrated into a single chip. Furthermore, the integrated circuit is not limited to an LSI, and may be realized using a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array), which can be programmed after LSI manufacturing, or a reconfigurable processor, which can reconfigure the connections and settings of circuit cells within an LSI, may also be used.

[0067] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, that technology may naturally be used to integrate the components included in the battery capacity adjustment device 18 into an integrated circuit.

[0068] In addition, this disclosure also includes forms obtained by making various modifications to the embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions in each embodiment within the scope of the present disclosure.

[0069] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0070] (Technology 1) A battery capacity adjustment device comprising: a battery capacity adjustment circuit that adjusts the capacity of a plurality of series-connected batteries that constitute a battery pack by transferring charge between the plurality of batteries; an acquisition unit that acquires temperatures at a plurality of positions in the battery pack; and a control unit that controls the battery capacity adjustment circuit to reduce the current flowing to a target battery included in the plurality of batteries, the target battery corresponding to the position with the highest temperature among the plurality of positions.

[0071] According to this, the target battery corresponding to the highest temperature among multiple positions in the battery pack is at risk of accelerated deterioration, so by reducing the current flowing through the target battery and suppressing the charge / discharge operation of the target battery, heat generation due to Joule heat in the target battery can be suppressed and the temperature of each battery can be equalized. Therefore, the rate of deterioration of batteries at risk of accelerated deterioration can be suppressed. Furthermore, by equalizing the temperature of each battery, the deterioration of each battery is more likely to be equalized, and the remaining capacity of each battery is more likely to be equalized.

[0072] (Technology 2) The battery capacity adjustment device according to Technology 1, wherein the plurality of positions are positions on the pack of the assembled battery.

[0073] In this way, it is not necessary to directly measure the temperature of each of the multiple batteries that make up the battery pack, and the temperature of the battery pack itself can be measured. By measuring the temperature of the battery pack itself, it is possible to measure the temperature of the ambient environment of the multiple batteries, and by reducing the current flowing to batteries in a high ambient temperature, it is possible to suppress the deterioration rate of batteries in a high ambient temperature environment.

[0074] (Technology 3) The battery capacity adjustment device according to Technology 2, wherein the target batteries are two or more batteries, and the control unit controls the battery capacity adjustment circuit so as to reduce the current flowing through the two or more batteries.

[0075] In this way, it is not necessary to measure the temperature of each of the multiple batteries one-to-one, and the temperatures may be measured at positions corresponding to two or more batteries on the battery pack. When the battery capacity adjustment device has only one DC / DC converter and there are two or more target batteries, the deterioration rate of the two or more batteries can be suppressed evenly by controlling the flow of current to be reduced for each of the two or more batteries one by one in turn. When the battery capacity adjustment device has a DC / DC converter for each of the multiple batteries, the deterioration rate of the two or more batteries can be suppressed by controlling the flow of current to be reduced for each of the two or more batteries simultaneously.

[0076] (Technology 4) The battery capacity adjustment device according to Technology 1, wherein the plurality of positions are positions on the plurality of batteries.

[0077] In this way, the temperature of each of the multiple batteries that make up the battery pack may be measured directly. By directly measuring the temperature of each of the multiple batteries, it is possible to identify batteries with high temperatures, and by reducing the current flowing through the hot battery, it is possible to suppress an increase in the internal resistance of that battery and thereby suppress the rate of deterioration of that battery.

[0078] (Technology 5) A battery capacity adjustment device described in any of Technologies 1 to 4, wherein the control unit controls the battery capacity adjustment circuit to reduce the current flowing to the target battery when the multiple positions include two positions where the temperature difference is greater than or equal to a predetermined temperature difference threshold.

[0079] According to this, if the multiple positions in the battery pack include two positions where the temperature difference is equal to or greater than a predetermined temperature difference threshold, the temperature at the position corresponding to the target battery (i.e., the position with the highest temperature) will be higher than the temperatures at the other positions, which may accelerate deterioration of the target battery. Therefore, in such a case, by initiating control to reduce the current flowing through the target battery, the rate of deterioration of the target battery can be effectively suppressed.

[0080] (Technology 6) A battery capacity adjustment device described in any of Technologies 1 to 5, wherein the control unit controls the battery capacity adjustment circuit to reduce the current flowing to the target battery when the lowest temperature among the temperatures at the multiple locations is equal to or higher than a predetermined temperature threshold.

[0081] According to this, when the lowest temperature among the temperatures at multiple positions in the battery pack is equal to or higher than a predetermined temperature threshold, the temperature at multiple positions in the battery pack is generally high, which may accelerate deterioration of the target battery. Therefore, in such a case, by initiating control to reduce the current flowing through the target battery, the rate of deterioration of the target battery can be effectively suppressed.

[0082] (Technology 7) The battery capacity adjustment device according to Technology 6, wherein the control unit controls the battery capacity adjustment circuit to reduce the current flowing through each of the plurality of batteries other than the target battery.

[0083] According to this, since the temperature is generally high at multiple positions in the battery pack, the deterioration rate of all batteries, including the target battery, can be suppressed. If the battery capacity adjustment device has only one DC / DC converter, the deterioration rate of the multiple batteries can be suppressed evenly by controlling each of the multiple batteries one by one in turn to reduce the current flow. If the battery capacity adjustment device has a DC / DC converter for each of the multiple batteries, the deterioration rate of the multiple batteries can be suppressed by controlling each of the multiple batteries simultaneously to reduce the current flow.

[0084] (Technology 8) A battery capacity adjustment device described in any of Technologies 1 to 7, wherein the acquisition unit acquires temperatures at the multiple locations before discharging or charging of the multiple batteries begins, and the control unit determines the target battery based on the temperatures at the multiple locations acquired before discharging or charging of the multiple batteries begins, and controls the battery capacity adjustment circuit after discharging or charging of the multiple batteries begins to reduce the current flowing to the target battery determined before discharging or charging of the multiple batteries begins.

[0085] For example, the battery pack may be installed in an environment where a specific location in the battery pack is likely to be exposed to direct sunlight or adjacent to a high-temperature source, and therefore the temperature at that specific location will rise even before the discharge or charging of the multiple batteries begins. In such cases, the target battery may be determined before the discharge or charging of the multiple batteries begins, and after the discharge or charging of the multiple batteries begins, the target battery for the control to reduce the flow of current may be fixed to the target battery determined before the discharge or charging of the multiple batteries begins. This eliminates the need to switch the target battery for the control to reduce the flow of current, and reduces the processing load.

[0086] (Technology 9) A battery capacity adjustment device described in any of Technologies 1 to 7, wherein the acquisition unit acquires temperatures at the multiple locations after discharging or charging of the multiple batteries begins, and the control unit sequentially determines the target battery based on the temperatures at the multiple locations acquired after discharging or charging of the multiple batteries begins, and controls the battery capacity adjustment circuit so as to reduce the current flowing to the sequentially determined target battery after discharging or charging of the multiple batteries begins.

[0087] According to this, after discharging or charging of multiple batteries begins, the position with the highest temperature among the multiple positions may change, and in such cases, it is possible to switch the target battery that is subject to control to reduce the flowing current.

[0088] (Technology 10) A battery capacity adjustment method executed by a battery capacity adjustment device, the battery capacity adjustment method including: an acquisition step of acquiring temperatures at multiple positions in a battery pack composed of multiple batteries connected in series; and an adjustment step of adjusting the capacities of the multiple batteries so as to reduce the current flowing through a target battery included in the multiple batteries, the target battery corresponding to the position with the highest temperature among the multiple positions.

[0089] This makes it possible to provide a battery capacity adjustment method that can suppress the rate of deterioration of a battery that may be accelerated.

[0090] The present disclosure can be applied to devices that equalize the remaining capacity of multiple batteries connected in series.

[0091] 2 Battery pack 4 Load 6A, 6B, 14A, 14B Relay 8 External power supply 10 AC power supply 12 Conversion unit 16 Ammeter 18 Battery capacity adjustment device 20 Battery capacity adjustment circuit 22 Monitoring unit 24 Control unit 36 ​​Insulated DC / DC converter b1 to b4 Batteries SWa to SWi Change-over switches

Claims

1. A battery capacity adjustment device comprising: a battery capacity adjustment circuit that adjusts the capacity of a plurality of series-connected batteries that constitute a battery pack by transferring charge between the plurality of batteries; an acquisition unit that acquires temperatures at a plurality of positions in the battery pack; and a control unit that controls the battery capacity adjustment circuit to reduce the current flowing to a target battery included in the plurality of batteries, the target battery corresponding to the position with the highest temperature among the plurality of positions.

2. The battery capacity adjustment device according to claim 1, wherein the plurality of positions are positions on the battery pack.

3. The battery capacity adjustment device according to claim 2, wherein the target batteries are two or more batteries, and the control unit controls the battery capacity adjustment circuit so as to reduce the current flowing through the two or more batteries.

4. The battery capacity adjustment device according to claim 1, wherein the plurality of positions are positions on the plurality of batteries.

5. The battery capacity adjustment device according to claim 1, wherein the control unit controls the battery capacity adjustment circuit to reduce the current flowing through the target battery when the plurality of positions includes two positions where the temperature difference is equal to or greater than a predetermined temperature difference threshold.

6. The battery capacity adjustment device according to claim 1, wherein the control unit controls the battery capacity adjustment circuit to reduce the current flowing to the target battery when the lowest temperature among the temperatures at the multiple locations is equal to or higher than a predetermined temperature threshold.

7. The battery capacity adjustment device according to claim 6, wherein the control unit controls the battery capacity adjustment circuit so as to reduce the current flowing through each of the plurality of batteries other than the target battery.

8. A battery capacity adjustment device as described in any one of claims 1 to 7, wherein the acquisition unit acquires temperatures at the multiple locations before discharging or charging of the multiple batteries begins, and the control unit determines the target battery based on the temperatures at the multiple locations acquired before discharging or charging of the multiple batteries begins, and controls the battery capacity adjustment circuit after discharging or charging of the multiple batteries begins so as to reduce the current flowing through the target battery determined before discharging or charging of the multiple batteries begins.

9. A battery capacity adjustment device as described in any one of claims 1 to 7, wherein the acquisition unit acquires temperatures at the multiple locations after discharging or charging of the multiple batteries begins, and the control unit sequentially determines the target battery based on the temperatures at the multiple locations acquired after discharging or charging of the multiple batteries begins, and controls the battery capacity adjustment circuit to reduce the current flowing through the sequentially determined target battery after discharging or charging of the multiple batteries begins.

10. A battery capacity adjustment method executed by a battery capacity adjustment device, comprising: an acquisition step of acquiring temperatures at multiple positions in a battery pack composed of multiple batteries connected in series; and an adjustment step of adjusting the capacities of the multiple batteries so as to reduce the current flowing through a target battery included in the multiple batteries, the target battery corresponding to the position with the highest temperature among the multiple positions.

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