Battery System

Abstract

To precisely calculate the temperature of a battery.SOLUTION: A battery system is a system in which a heat transfer medium for cooling a battery pack including a plurality of cells is also used to raise the temperature of the battery pack, and comprises: a second thermistor that detects the temperature of a cell which tends to have higher temperature among the plurality of cells at the time of cooling; and an ECU. The ECU calculates the temperature of a cell which tends to have lower temperature among the plurality of cells at the time of rising temperature by correcting the detected temperature of the second thermistor based on tendencies of the temperatures of the plurality of cells at the time of cooling and the time of rising temperature (Step S121 ot Step S123).SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a battery system, and more particularly to a battery system in which a heat medium for cooling a battery pack including a plurality of cells is also used to raise the temperature of the battery pack. [Background technology]

[0002] Conventionally, there has been a power supply device that accurately estimates the temperature of a battery cell, some of which is cooled by a cooling device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-169293 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the device of Patent Document 1, when the heat medium for cooling the battery cells is also used for heating, a problem occurs in that it becomes difficult to estimate the temperature of the battery cells.

[0005] This disclosure has been made to solve such problems, and has as its objective to provide a battery system capable of calculating the temperature of a battery with high accuracy. [Means for solving the problem]

[0006] The battery system according to the present disclosure is a battery system that uses a heat medium for cooling a battery pack including a plurality of cells also for heating the battery pack, and includes a sensor that detects the temperature of a cell that tends to have a higher temperature among the plurality of cells during cooling, and a processor. The processor calculates the temperature of a low-temperature cell that tends to have a lower temperature among the plurality of cells during heating by correcting the temperature detected by the sensor based on the temperature trends of the plurality of cells during cooling and heating.

[0007] According to this configuration, the temperature of the cell that tends to be higher during cooling is corrected based on the temperature trends of the cells during cooling and heating, thereby calculating the temperature of the low-temperature cell that tends to be lower during heating. As a result, it is possible to provide a battery system that can accurately calculate the temperature of the battery.

[0008] The device may further include a memory that pre-stores, for each detected temperature, the difference between the detected temperature and the temperature of a cell that tends to have a lower temperature when the temperature is rising as a correction temperature, and the processor may calculate the temperature of the low-temperature cell when the temperature is rising by subtracting the correction temperature corresponding to the detected temperature stored in the memory from the detected temperature.

[0009] According to this configuration, the temperature of the low-temperature cell is calculated during heating by subtracting from the detected temperature a correction temperature corresponding to the detected temperature among pre-stored correction temperatures, which is the difference between the detected temperature and the temperature of the cell that tends to be lower during heating. As a result, the temperature of the battery can be calculated with high accuracy using the pre-stored correction temperatures.

[0010] The processor may subtract the correction temperature according to the time elapsed after the end of the temperature rise. With this configuration, the correction by the correction temperature can be reduced as the cell temperature gradually decreases after the temperature rise. As a result, the battery temperature can be calculated with high accuracy after the temperature rise is completed. Effect of the Invention

[0011] According to this disclosure, it is possible to provide a battery system capable of calculating the temperature of a battery with high accuracy. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an example of an overall configuration of a thermal management system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of a thermal management circuit according to the embodiment; [Diagram 3] FIG. 2 is a perspective view for explaining cooling and heating of a battery. [Figure 4] 4 is a schematic diagram and a graph for explaining cooling and heating of a battery. [Diagram 5] 5 is a flowchart showing the flow of a battery temperature correction process in this embodiment. [Figure 6] FIG. 4 is a diagram for explaining a map used in the battery temperature correction process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters, and the description thereof will not be repeated.

[0014] In the following, a configuration in which the thermal management system according to the present disclosure is mounted on a vehicle will be described as an example. The vehicle is preferably a vehicle equipped with a battery for driving, for example, an electric vehicle (BEV: Battery Electric Vehicle). The vehicle may be a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), or a fuel cell electric vehicle (FCEV: Fuel Cell Electric Vehicle). However, the use of the thermal management system according to the present disclosure is not limited to vehicles.

[0015] <Overall composition> 1 is a diagram showing an example of an overall configuration of a thermal management system 1 according to an embodiment of the present disclosure. The thermal management system 1 includes a thermal management circuit 100, an electronic control unit (ECU) 500, and an HMI (Human Machine Interface) 600.

[0016] A heat medium flows through the thermal management circuit 100. The thermal management circuit 100 includes, for example, a high-temperature circuit 110, a radiator 120, a low-temperature circuit 130, a condenser 140, a refrigeration cycle 150, a chiller 160, a battery circuit 170, and a five-way valve 180.

[0017] The high-temperature circuit 110 includes, for example, a water pump (W / P) 111, an electric heater 112, a three-way valve 113, a heater core 114, and a reservoir tank (R / T) 115. The radiator 120 is connected (i.e., shared) to both the high-temperature circuit 110 and the low-temperature circuit 130. The radiator 120 includes a high-temperature (HT) radiator 121 and a low-temperature (LT) radiator 122 (all of which are shown in FIG. 2). The low-temperature circuit 130 includes, for example, a water pump 131, a smart power unit (SPU) 132, a power control unit (PCU) 133, an oil cooler (O / C) 134, and a step-up / step-down converter 135. The condenser 140 is connected to both the high-temperature circuit 110 and the refrigeration cycle 150. The refrigeration cycle 150 includes, for example, a compressor 151, an expansion valve 152, an evaporator 153, an evaporative pressure regulator (EPR) 154, and an expansion valve 155. The chiller 160 is connected to both the refrigeration cycle 150 and a battery circuit 170. The battery circuit 170 includes, for example, a water pump 171, an electric heater 172, a battery 173, a bypass path 174, and a reservoir tank 175. The five-way valve 180 is connected to the low-temperature circuit 130 and the battery circuit 170. The configuration of the thermal management circuit 100 will be described in detail with reference to FIG. 2.

[0018] The ECU 500 controls the thermal management circuit 100. The ECU 500 includes a processor 501, a memory 502, a storage 503, and an interface 504.

[0019] The processor 501 is, for example, a central processing unit (CPU) or a micro-processing unit (MPU). The memory 502 is, for example, a random access memory (RAM). The storage 503 includes at least one of a hard disk drive (HDD), a solid state drive (SSD), and a rewritable non-volatile memory such as a flash memory. The storage 503 stores a system program including an operating system (OS) and a control program including computer-readable codes required for control calculations. The processor 501 realizes various processes by reading the system program and the control program, expanding them in the memory 502, and executing them. The interface 504 controls communication between the ECU 500 and the components of the thermal management circuit 100.

[0020] The ECU 500 generates a control command based on sensor values ​​(e.g., temperatures at various locations) acquired from various sensors (e.g., a first thermistor 511, a second thermistor 512, and a third thermistor 513 described below) included in the thermal management circuit 100, a user operation accepted by the HMI 600, and the like, and outputs the generated control command to the thermal management circuit 100. The ECU 500 may be divided into multiple ECUs for each function. Also, while FIG. 1 shows an example in which the ECU 500 includes one processor 501, the ECU 500 may include multiple processors. The same applies to the memory 502 and the storage 503.

[0021] In this specification, the term "processor" is not limited to a processor in the narrow sense that executes processing by a stored program method, but may include hardwired circuits such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field-Programmable Gate Arrays). Therefore, the term "processor" may be interpreted as a processing circuitry in which processing is defined in advance by computer-readable code and / or hardwired circuits.

[0022] The HMI 600 is a display with a touch panel, an operation panel, a console, etc. The HMI 600 accepts a user operation for controlling the thermal management system 1. The HMI 600 outputs a signal indicating the user operation to the ECU 500.

[0023] <Thermal management circuit configuration> 2 is a diagram showing an example of the configuration of the thermal management circuit 100 in this embodiment. The heat medium (usually hot water) circulating in the high-temperature circuit 110 flows through one or both of a first path of the water pump 111-condenser 140-electric heater 112-three-way valve 113-heater core 114-reservoir tank 115-water pump 111 and a second path of the water pump 111-condenser 140-electric heater 112-three-way valve 113-high-temperature radiator 121-reservoir tank 115-water pump 111.

[0024] The heat medium (coolant) circulating in the low-temperature circuit 130 flows through a route including the water pump 131 - SPU 132 - PCU 133 - oil cooler 134 - step-up / step-down converter 135 - five-way valve 180 - low-temperature radiator 122 - water pump 131.

[0025] The water pump 131 circulates the heat medium in the low-temperature circuit 130 in accordance with a control command from the ECU 500. The SPU 132 controls the charging and discharging of the battery 173 in accordance with a control command from the ECU 500. The PCU 133 converts the DC power supplied from the battery 173 into AC power in accordance with a control command from the ECU 500, and supplies the AC power to a motor built in the transaxle. The oil cooler 134 circulates lubricating oil for the motor using an electric oil pump (EOP: Electrical Oil Pump). The SPU 132, the PCU 133, the oil cooler 134, and the step-up / step-down converter 135 are cooled by the heat medium circulating in the low-temperature circuit 130. The five-way valve 180 switches the paths of the heat medium in the low-temperature circuit 130 and the battery circuit 170 in accordance with a control command from the ECU 500. The low-temperature radiator 122 is disposed in the vicinity of the high-temperature radiator 121 and exchanges heat with the high-temperature radiator 121 .

[0026] The heat medium (gas phase refrigerant or liquid phase refrigerant) circulating through the refrigeration cycle 150 flows through one or both of a first path of the compressor 151-condenser 140-expansion valve 152-evaporator 153-EPR 154-compressor 151 and a second path of the compressor 151-condenser 140-expansion valve 155-chiller 160-compressor 151.

[0027] The heat medium (coolant) circulating in the battery circuit 170 flows through one or both of a first path of the water pump 171-chiller 160-five-way valve 180-electric heater 172-battery 173-reservoir tank 175-water pump 171 and a second path of the water pump 171-chiller 160-five-way valve 180-bypass path 174-reservoir tank 175-water pump 171. The reservoir tank 175 is provided at a portion where the first path and the bypass path 174 join together.

[0028] The water pump 171 circulates the heat medium in the battery circuit 170 in accordance with a control command from the ECU 500. The chiller 160 cools the heat medium circulating in the battery circuit 170 by heat exchange between the heat medium circulating in the refrigeration cycle 150 and the heat medium circulating in the battery circuit 170. The electric heater 172 heats the heat medium in accordance with a control command from the ECU 500. The battery 173 supplies electric power for traveling to a motor built in the transaxle. The battery 173 can be heated using the electric heater 172 or cooled using the chiller 160. The bypass path 174 is provided so that the heat medium bypasses the electric heater 172 and the battery 173. When the heat medium flows through the bypass path 174, a temperature change of the heat medium caused by heat absorption or heat release between the heat medium and the battery 173 can be suppressed. The reservoir tank 175 stores a portion of the heat medium in the battery circuit 170 to maintain the pressure and amount of the heat medium in the battery circuit 170 .

[0029] The five-way valve 180 is provided with five ports P1 to P5. The port P1 is an inlet port into which the heat medium flows in from the chiller 160. The port P2 is an outlet port from which the heat medium flows out toward the electric heater 172 and the battery 173 (battery 173 is shown representatively) of the battery circuit 170. The port P3 is an inlet port into which the heat medium flows in from the SPU 132, the PCU 133, the oil cooler 134, and the step-up / step-down converter 135 (PCU 133 is shown representatively) of the low-temperature circuit 130. The port P4 is an outlet port from which the heat medium flows out toward the bypass path 174 of the battery circuit 170. The port P5 is an outlet port from which the heat medium flows out toward the low-temperature radiator 122.

[0030] <Connection pattern> In the first communication pattern by the five-way valve 180, a path that communicates between the port P1 and the port P5 and a path that communicates between the port P3 and the port P2 are formed by the five-way valve 180. In this case, the low temperature circuit 130 and the battery circuit 170 are connected in series. As a result, the thermal management circuit 100 is in a series connection state in which the reservoir tank 175, the water pump 171, and the water pump 131 are connected in series. In this case, the water pump 171 is provided upstream of the water pump 131 with respect to the flow direction of the heat medium, starting from the reservoir tank 175.

[0031] In the second communication pattern, the five-way valve 180 forms a path that communicates between the ports P1 and P2, and a path that communicates between the ports P3 and P5. These two paths are independent of each other, and no other path is formed to connect the two paths. In this case, the low temperature circuit 130 and the battery circuit 170 are connected in parallel completely independently. As a result, the thermal management circuit 100 is in a non-series connection state in which the water pump 171 and the water pump 131 are not connected in series (arranged in parallel).

[0032] The heat medium is injected into the heat management circuit 100 under the condition that the heat management circuit 100 is switched to the serial connection state. First, the heat medium is injected into the reservoir tank 175. The heat medium injected into the reservoir tank 175 flows in the following order: water pump 171-chiller 160-five-way valve 180-LT radiator 122-water pump 131-PCU 133-five-way valve 180-battery 173-reservoir tank 175. At this time, the five-way valve 180 may be controlled so that the heat medium flows through the bypass path 174. That is, the heat medium from the port P3 may flow through the port P4 in addition to (or instead of) the port P2.

[0033] <Battery cooling and heating> Fig. 3 is a perspective view for explaining the cooling and temperature rise of battery 173. Fig. 4 is a schematic diagram and a graph for explaining the cooling and temperature rise of battery 173. With reference to Figs. 3 and 4, battery 173 includes a plurality of assembled batteries 730. Assembled battery 730 includes a plurality of cells 731, end plates 732, 733, an intermediate plate 734, and piping 735.

[0034] In this embodiment, the cell 731 is a lithium ion battery. However, the cell 731 is not limited thereto, and may be another secondary battery, for example, an all-solid-state battery or a nickel-metal hydride battery. The cells 731 are stacked. As shown in FIG. 4A, end plates 732 and 733 are disposed at both ends of the stacked cells 731 and are used to restrain the stacked cells 731. The middle plate 734 is disposed near the center of the stacked cells 731. The piping 735 is provided so as to enable heat exchange between each of the cells 731 and the heat medium flowing through the piping 735. The heat medium flows into each piping 735 from an inlet piping 736 on the side of the electric heater 172 upstream of the battery 173, and flows out into an outlet piping 737 on the side of the reservoir tank 115 downstream of the battery 173 (see FIG. 2).

[0035] 4(A), the first thermistor 511 is attached so as to be able to detect the temperature of the cell 731A on the most downstream side of the pipe 735. The third thermistor 513 is attached so as to be able to detect the temperature of the cell 731C on the most upstream side of the pipe 735.

[0036] 4(B), the temperature of the cell 731 during cooling is higher on the downstream side compared to the upstream side of the pipe 735. The end plates 732, 733 and the intermediate plate 734 are formed of metal. Therefore, during cooling of the cell 731, the temperature of the cell 731 is transferred to the periphery via the end plates 732, 733 and the intermediate plate 734, so that the temperature of the cell 731 around the end plates 732, 733 and the intermediate plate 734 becomes lower than that of the other cells 731.

[0037] As a result, during cooling, the cell 731 that tends to have a high temperature (here, the highest temperature) is cell 731B between the downstream end plate 732 and the intermediate plate 734. The second thermistor 512 is attached so as to be able to detect the temperature of this cell 731B. As a result, it becomes possible to obtain the temperature of cell 731B that tends to have a high temperature (here, the highest temperature) among the multiple cells 731 by the second thermistor 512.

[0038] The first thermistor 511 , the second thermistor 512 and the third thermistor 513 transmit signals indicative of the detected temperatures to the interface 504 of the ECU 500 .

[0039] During cooling, cells 731 that tend to have high temperatures include other cells 731 in the vicinity of cell 731B. However, depending on the conditions, the cell 731 that has the highest temperature among the multiple cells 731 may be different from cell 731B.

[0040] When this heat medium is also used to heat the battery 173, the temperature of the cell 731 becomes lower on the downstream side of the pipe 735 compared to the upstream side, as shown in Fig. 4(C). However, as described above, since the end plates 732, 733 and the intermediate plate 734 are made of metal, when the temperature of the cell 731 increases, the surrounding temperature is transferred to the cell 731 via the end plates 732, 733 and the intermediate plate 734. Therefore, the temperature of the cell 731 around the end plates 732, 733 and the intermediate plate 734 becomes higher than that of the other cells 731.

[0041] As a result, the cell 731 that will have the lowest temperature during temperature rise will be the cell 731 between the downstream end plate 732 and the intermediate plate 734. However, this cell 731 that will have the lowest temperature is not necessarily the same as the cell 731B to which the second thermistor 512 is attached. This gives rise to a problem in that it becomes difficult to identify the temperature of the cell 731 that will have the lowest temperature during temperature rise.

[0042] Therefore, ECU 500 calculates the temperature of cell 731 that tends to have a lower temperature among the multiple cells 731 during temperature rise by correcting the detected temperature of second thermistor 512 based on the temperature trends of the multiple cells 731 during cooling and during temperature rise. As a result, the temperature of cell 731 that tends to have a higher temperature among the multiple cells 731 during cooling is corrected based on the temperature trends of the multiple cells 731 during cooling and during temperature rise, thereby calculating the temperature of cell 731 that tends to have a lower temperature among the multiple cells 731 during temperature rise (here, the cell 731 with the lowest temperature). As a result, the temperature of battery 173 can be calculated with high accuracy.

[0043] 5 is a flowchart showing a flow of the battery temperature correction process in this embodiment. Referring to Fig. 5, this battery temperature correction process is called by ECU 500 from a higher-level process at every predetermined control period and executed.

[0044] In the battery temperature correction process, first, processor 501 of ECU 500 determines whether or not the temperature of battery 173 is increasing (step S111). If processor 501 determines that the temperature is not increasing (NO in step S111), processor 501 determines whether or not attenuation of the correction temperature, which will be described later, is being performed (step S112).

[0045] When it is determined that the correction temperature is not being attenuated (NO in step S112), processor 501 identifies the measured temperature of cell 731B using the signal from second thermistor 512 (step S113), and sets this measured temperature as the temperature of cell 731B (step S114). After that, processor 501 returns the process to be executed to the upper process that called this battery temperature correction process.

[0046] On the other hand, if it is determined that the battery 173 is heating up (YES in step S111), the processor 501 uses the signal from the second thermistor 512 to identify the measured temperature of cell 731B (step S121), and identifies a correction temperature corresponding to the measured temperature of cell 731B using a correction map pre-stored in the memory 502 or storage 503 (step S122).

[0047] FIG. 6 is a diagram for explaining a map used in the battery temperature correction process. FIG. 6(A) is a diagram for explaining the correction map. Referring to FIG. 6(A), the relationship between the measured temperature of the cell 731B and the correction temperature at the measured temperature is specified in advance as a correction map by an experiment or simulation of the thermal management system 1 so that the temperature of the cell 731 with the lowest calculated temperature is close to the actual temperature, and this correction map is stored in the memory 502 or the storage 503. For example, the correction map is used to specify that the correction temperatures corresponding to the measured temperatures of -3T°C, -2T°C, . . . , 5T°C are A1°C, A2°C, . . . , AN°C.

[0048] Returning to FIG. 5, the processor 501 subtracts the correction temperature identified in step S122 from the measured temperature identified in step S121 to calculate the temperature of the cell 731 with the lowest temperature (step S123).

[0049] Next, the processor 501 determines whether the current control period is the period at the end of the temperature rise (step S124). If it is determined that the control period is the period at the end of the temperature rise (YES in step S124), the processor 501 starts exponential decay of the correction temperature with a predetermined time constant (step S125) and sets the decay in progress flag to the ON state (step S126).

[0050] If it is determined that the attenuation of the correction temperature is being performed (YES in step S112), if it is determined that the temperature rise has not ended (NO in step S124), or after step S126, the processor 501 determines whether the current control period is the control period immediately after the ignition switch (power switch) is turned on (step S131).

[0051] If it is determined that the ignition switch has just been turned on (YES in step S131), the processor 501 specifies the damping premium rate of the correction temperature corresponding to the elapsed time since the ignition switch was turned off in the damping premium rate map (step S132).

[0052] Referring again to Fig. 6, Fig. 6(B) is a diagram for explaining the attenuation premium rate map. Referring to Fig. 6(B), the relationship between the IG off time, which is the elapsed time after the ignition switch is turned off, and the attenuation rate of the corrected temperature at that IG off time is specified in advance as the attenuation premium rate map by an experiment or simulation of the thermal management system 1 so that the temperature of the cell 731 with the lowest calculated temperature is close to the actual temperature, and this attenuation premium rate map is stored in the memory 502 or the storage 503. For example, the attenuation premium rate map is used to specify that the attenuation rates corresponding to IG off times of 0 minutes, M minutes, 2M minutes, ..., 10M minutes are 1x, 0.9x, 0.8x, ..., 0x.

[0053] Returning to FIG. 5, if it is determined that the ignition switch has not been turned on immediately (NO in step S131), or after step S132, the processor 501 uses the signal from the second thermistor 512 to determine the measured temperature of cell 731B (step S133), and determines the correction temperature during decay (step S134).

[0054] Next, the processor 501 subtracts the value obtained by multiplying the decay correction temperature identified in step S134 by the decay premium rate identified in step S132 from the measured temperature identified in step S133 to calculate the temperature of the cell 731 with the lowest temperature (step S135).

[0055] Processor 501 determines whether or not the corrected temperature is below a predetermined minute value (step S141). The predetermined minute value is a value that is compared with the corrected temperature to determine whether or not to end the attenuation of the corrected temperature, and if the value falls below this value, the attenuation of the corrected temperature is ended. If it is determined that the corrected temperature is not below the predetermined minute value (NO in step S141), processor 501 returns the process to be executed to the upper process that called this battery temperature correction process.

[0056] On the other hand, when it is determined that the corrected temperature is less than the predetermined minimal value (YES in step S141), processor 501 ends the attenuation of the corrected temperature (step S142), resets the attenuation premium rate to 0 (step S143), resets the corrected temperature to 0 (step S144), and sets the attenuation in progress flag to the OFF state (step S145). After that, processor 501 returns the process to be executed to the upper process that called this battery temperature correction process.

[0057] [Variations] (1) In the above-described embodiment, as shown in Fig. 1 etc., the heat medium passing through the battery 173 is the coolant. However, this is not limited to this, and the heat medium may be something else, for example, it may be water or another refrigerant.

[0058] (2) In the embodiment described above, the sensor that detects the temperature of the cell 731 is a thermistor as shown in Fig. 4. However, this is not limited to this, and any other sensor that can detect the temperature of the cell 731 may be used, such as a thermocouple.

[0059] (3) As shown in step S125 of Fig. 5, the correction temperature is attenuated exponentially with a predetermined time constant. However, the present invention is not limited to this, and the correction temperature may be subtracted according to the elapsed time after the end of the temperature rise. For example, the correction temperature may be attenuated linearly.

[0060] (4) The above-described embodiment can be understood as disclosing a battery system, a thermal management system 1, or a vehicle including the battery 173. It can be understood as disclosing a battery temperature correction method or a battery temperature correction program executed by the battery system, the thermal management system 1, or a vehicle including the battery 173.

[0061] [summary] 1 to 4, the battery system is a system that uses a heat medium for cooling a battery pack 730 including a plurality of cells 731 also for heating the battery pack 730, and includes a second thermistor 512 that detects the temperature of a cell 731B that tends to have a higher temperature among the plurality of cells 731 during cooling, and an ECU 500. As shown in Fig. 5, the ECU 500 calculates the temperature of a low-temperature cell 731 that tends to have a lower temperature among the plurality of cells 731 during heating by correcting the detected temperature of the second thermistor 512 based on the temperature trends of the plurality of cells 731 during cooling and heating (for example, steps S121 to S123).

[0062] In this way, the temperature of cell 731B, which tends to have a higher temperature among the multiple cells 731 during cooling, is corrected based on the temperature trends of the multiple cells 731 during cooling and heating, thereby calculating the temperature of low-temperature cell 731, which tends to have a lower temperature among the multiple cells 731 during heating. As a result, the temperature of battery 173 can be calculated with high accuracy.

[0063] (2) As shown in Figures 1 and 4, the ECU 500 may further include a memory 502 or storage 503 that stores in advance, for each detected temperature, the difference between the detected temperature and the temperature of cell 731 that tends to be low during temperature rise as a correction temperature. As shown in Figure 5, the ECU 500 may calculate the temperature of the low-temperature cell during temperature rise by subtracting the correction temperature corresponding to the detected temperature stored in the memory 502 or storage 503 from the detected temperature (for example, steps S121 to S123).

[0064] In this way, the correction temperature corresponding to the detected temperature is subtracted from the detected temperature among pre-stored correction temperatures, which are the difference between the detected temperature and the temperature of the cell 731 that tends to be low during temperature rise, to calculate the temperature of the cell 731 that is low during temperature rise. As a result, the temperature of the battery 173 can be calculated with high accuracy using the pre-stored correction temperature.

[0065] (3) As shown in FIG. 5, ECU 500 may subtract the correction temperature according to the time that has elapsed since the end of the temperature increase (for example, step S125, and steps S132 to S135).

[0066] This allows the correction by the correction temperature to be reduced as the temperature of the cell 731 gradually decreases after the temperature increase. As a result, the temperature of the battery 173 can be calculated with high accuracy after the temperature increase is completed.

[0067] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0068] 1 Thermal management system, 100 Thermal management circuit, 110 High temperature circuit, 111, 131, 171 Water pump, 112, 172 Electric heater, 113 Three-way valve, 114 Heater core, 115, 175 Reservoir tank, 120 Radiator, 121 High temperature radiator, 122 Low temperature radiator, 130 Low temperature circuit, 133 PCU, 134 Oil cooler, 135 Boost / Buck converter, 140 Condenser, 150 Refrigeration cycle, 151 Compressor, 152, 155 Expansion valve, 153 Evaporator, 160 Chiller, 170 Battery circuit, 173 Battery, 174 Bypass path, 180 Five-way valve, 500 ECU, 501 Processor, 502 Memory, 503 Storage, 504 Interface, 511 First thermistor, 512 second thermistor, 513 third thermistor, 600 HMI, 730 battery pack, 731, 731A, 731B, 731C cells, 732, 733 end plate, 734 intermediate plate, 735 piping, 736 inlet piping, 737 outlet piping.

Claims

1. A battery system in which a heat medium for cooling a battery pack including a plurality of cells is also used for raising the temperature of the battery pack, a sensor for detecting a temperature of a first cell having a higher temperature among the plurality of cells during cooling; a processor; The processor calculates the temperature of a second cell, which has a lower temperature among the multiple cells, during heating, by correcting the detected temperature of the sensor during heating of the first cell, which has a higher temperature among the multiple cells, during cooling.

2. a memory for storing in advance, for each of the detected temperatures, a difference between the detected temperature and a temperature of the second cell having a lower temperature during heating, as a correction temperature; The battery system according to claim 1 , wherein the processor calculates the temperature of the second cell during temperature rise by subtracting the correction temperature corresponding to the detected temperature stored in the memory from the detected temperature.

3. The battery system according to claim 2 , wherein the processor subtracts the correction temperature according to an elapsed time after completion of temperature increase.

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