Battery system

Abstract

The secondary battery is cooled to prevent the transmission current from being limited during power transmission. [Solution] The ECU executes a process that includes the following steps when the conditions for executing transmission control are met (YES in S100): acquiring the limit history (S102); executing cooling control when there was a current limit in the previous transmission control (NO in S104) and the battery temperature is greater than the starting temperature t(2) (YES in S108) (S110); implementing current limiting when the battery temperature is greater than the limit temperature t(1) (YES in S112) (S114); terminating the cooling control when the conditions for terminating the cooling control are met (YES in S118) (S120); and storing the limit history (S122).

Description

Technical Field

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[0001] The present disclosure relates to a battery system.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2001-313092 (Patent Document 1) discloses a technique in which when the deviation between the estimated temperature of a secondary battery and the actual battery temperature is greater than a threshold value, a cooling fan is driven, and when the deviation does not become less than the threshold value even after driving, an abnormality is outputted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Even after starting the cooling of the secondary battery during power transmission, if the temperature of the secondary battery rises, it may be considered to limit the transmission current. However, when the transmission current is limited, the time required for power transmission may also be prolonged.

[0005] The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a battery system that cools a secondary battery so that the transmission current is not limited during power transmission.

Means for Solving the Problems

[0006] A battery system according to a certain aspect of this disclosure comprises a secondary battery, a transmission system for transmitting power to and from the secondary battery, a temperature control device for adjusting the temperature of the secondary battery, and a control device that controls the temperature control device to cool the secondary battery if the temperature of the secondary battery exceeds a first threshold during power transmission control. The control device limits the transmitted power transmitted between the secondary battery and the transmission system if the temperature of the secondary battery exceeds a second threshold which is greater than the first threshold. If the transmitted power was limited in the previous transmission control, the control device sets the first threshold in the current transmission control to a value smaller than the first threshold in the previous transmission control.

[0007] In this way, the secondary battery is cooled using the adjustment device at an earlier stage in the current transmission control compared to the previous transmission control, thus preventing the secondary battery temperature from exceeding the second threshold. Therefore, the transmission power is not limited, and the time required for power transmission is suppressed.

[0008] In one embodiment, the control device increases the amount by which the first threshold value is lowered when the secondary battery is in a degraded state compared to when it is in a new state.

[0009] In this way, as the battery deteriorates, its internal resistance increases and the amount of heat generated increases. Therefore, by lowering the first threshold value more significantly than when the battery is new, it is possible to prevent the secondary battery temperature from exceeding the second threshold value.

[0010] Furthermore, in one embodiment, the control device reduces the first threshold value in the current transmission control by at least the amount by which the temperature of the secondary battery exceeded the second threshold value in the previous transmission control, and sets the first threshold value in the current transmission control to a value smaller than the first threshold value in the previous transmission control.

[0011] In this way, the first threshold in the current transmission control is set by reducing the amount by which the secondary battery temperature exceeded the second threshold in the previous transmission control, thereby reliably preventing the secondary battery temperature from exceeding the second threshold.

[0012] In one further embodiment, the control device releases the power limit if the temperature of the secondary battery falls below a second threshold while the power limit is being applied.

[0013] This approach prevents the time required for power transmission from becoming excessively long due to the removal of the restriction. [Effects of the Invention]

[0014] According to this disclosure, a battery system can be provided that cools a secondary battery so that the transmission current is not limited during power transmission. [Brief explanation of the drawing]

[0015] [Figure 1] This is a diagram showing an example of the configuration of a power transmission system. [Figure 2] This figure shows an example of the history of changes in battery temperature during power transmission in both new and deteriorated batteries. [Figure 3] This flowchart shows an example of a process performed by the ECU. [Figure 4] This figure shows an example of the change in battery temperature during the Nth and N+1th battery control cycles. [Figure 5] This figure shows an example of the relationship between the starting temperature and the degree of degradation. [Modes for carrying out the invention]

[0016] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0017] Hereinafter, an example of the configuration of the battery system 1 according to the present embodiment will be described. FIG. 1 is a diagram showing an example of the configuration of the battery system 1. As shown in FIG. 1, the battery system 1 includes a vehicle 200 and a power transmission stand 10 outside the vehicle 200. The vehicle 200 may be any vehicle capable of power transmission with an external facility, for example, an electric vehicle such as an electric car or a plug-in hybrid car.

[0018] The vehicle 200 includes an ECU (Electronic Control Unit) 100 which is a control device, an adjustment device 150, a battery 214, an inverter 216, an MG (Motor Generator) 218, and an inlet 220.

[0019] The battery 214 may be any rechargeable power storage device, for example, a secondary battery such as a nickel-hydrogen battery or a lithium-ion battery having a liquid or solid electrolyte, or a large-capacity capacitor or the like may be used instead of the battery 214.

[0020] The inverter 216 is configured to be able to convert the DC power of the battery 214 and the AC power of the MG 218 bidirectionally according to a control signal from the ECU 100.

[0021] The MG 218 is a drive source for driving the drive wheels 222 of the vehicle 200 and is constituted by a three-phase AC rotating electric machine or the like. The MG 218 has a function as an electric motor (motor) for driving the vehicle 200 using the power of the battery 214 and a function as a generator (generator) for generating power (for example, regenerative power) for charging the battery 214.

[0022] The inlet 220 has a shape to which the connector 17 of the power transmission stand 10 can be attached. The inlet 220 is electrically connected to the battery 214.

[0023] The ECU 100 is connected to a voltage sensor 102 for obtaining the voltage of the battery 214, a current sensor 104 for obtaining the current, and a temperature sensor 106 for obtaining the temperature of the battery 214. The ECU 100 includes a CPU (Central Processing Unit) and memory (neither of which are shown). Based on the signals received from each sensor, as well as information such as maps and programs stored in the memory, the ECU 100 controls each device so that the vehicle 200 reaches a desired state.

[0024] The ECU 100 has the function of sequentially calculating the State of Charge (SOC) of the battery 214 based on the detected values ​​of the voltage sensor 102, current sensor 104, and temperature sensor 106. Various known methods can be used to calculate the SOC, such as a method using current value integration (Coulomb count) or a method using open circuit voltage (OCV) estimation. The ECU 100 is configured to communicate with the communication unit 13 of the power transmission stand 10, which will be described later.

[0025] The adjustment device 150 is configured to adjust the temperature of the battery 214 in response to a control signal from the ECU 100. The adjustment device 150 includes a heating device 152 for heating the battery 214 and a cooling device 154 for cooling the battery 214. The heating device 152 may be, for example, an electric heater (not shown). The cooling device 154 may be, for example, a cooling fan (not shown). The cooling device 154 may consist of, for example, a heat-exchangeable radiator, a medium (e.g., coolant or gas), a pump for pressurizing the medium, and a cooling passage through which the medium flows.

[0026] When the ECU 100 raises the temperature of the battery 214, it activates the heating device 152 while shutting down the cooling device 154. For example, the ECU 100 activates the heating device 152 when the temperature of the battery 214 is lower than a predetermined temperature range that includes the target temperature.

[0027] When the ECU 100 needs to cool the battery 214, it activates the cooling device 154 while shutting down the heating device 152. Each of the heating device 152 and the cooling device 154 is configured to operate using at least one of the following power sources: power supplied (transmitted) from the power transmission stand 10 to the inlet 220 (power from an external power source) and power supplied (transmitted) from the battery 214.

[0028] The power transmission stand 10 is an electrical device that includes a communication unit 13, a control unit 14, a transmission unit 15, a cable 16, and a connector 17. The power transmission stand 10, for example, transmits power from the grid power supply 400 to the battery 214 of the vehicle 200 to charge the battery 214, or transmits power from the battery 214 to the grid power supply 400 to discharge the battery 214.

[0029] When the connector 17 is connected to the inlet 220 of the vehicle 200, the communication unit 13 performs wired communication such as power line communication, CAN (Control Area Network) communication, or LAN communication with the ECU 100 of the vehicle 200 via the cable 16. Note that communication may also be performed using wireless communication of various standards (for example, Wi-Fi).

[0030] The control unit 14 controls the operation of the transmission unit 15 (for example, transmission voltage and transmission current) based on control signals received from the ECU 100. The control unit 14 includes a CPU and memory (neither of which are shown). The control unit 14 controls the transmission unit 15 based on information received from the vehicle 200 using the communication unit 13 and information such as maps and programs stored in the memory.

[0031] The transmission unit 15 converts AC power from the grid power supply 400 to DC power, or converts DC power from the battery 214 to AC power, according to a control signal from the control unit 14. One end of the cable 16 is connected to the transmission unit 15. The other end of the cable 16 is connected to a connector 17.

[0032] The connector 17 has a shape that allows it to be attached to the inlet 220. When the connector 17 is attached to the inlet 220, it enters one of two states based on a control signal received by the control unit 14 from the ECU 100: a first state in which DC power can be supplied from the transmission unit 15 to the battery 214, or a second state in which AC power can be supplied from the transmission unit 15 to the grid power supply 400. For example, if the ECU 100 requests external charging, it sends a control signal to the control unit 14 so that the first state is entered when the connector 17 is attached to the inlet 220. For example, if the ECU 100 requests discharge to the power transmission stand 10, it sends a control signal to the control unit 14 so that the second state is entered when the connector 17 is attached to the inlet 220.

[0033] In this embodiment, the "secondary battery" is comprised of a battery 214, the "transmission system" is comprised of an inlet 220 and a power line connecting the battery 214 and the inlet 220, the "control device" is comprised of an ECU 100, and the "adjustment device" is comprised of an adjustment device 150.

[0034] For example, the ECU 100 requests a rapid charge if the State of Charge (SOC) of the battery 214 is below a threshold. Also, for example, when performing power transmission (hereinafter referred to as V2H: Vehicle to Home) between the vehicle 200 and a facility where the power transmission stand 10 is installed (for example, a home), the ECU 100 requests discharge when using the battery 214 as the power source for the facility, and requests charging when storing surplus power in the battery 214.

[0035] During power transmission using the battery 214, the ECU 100 calculates the State of Charge (SOC) and temperature of the battery 214 using the detected values ​​of the voltage sensor 102, current sensor 104, and temperature sensor 106. During power transmission using the battery 214, if the temperature of the battery 214 exceeds a first threshold, the ECU 100 activates the cooling device 154 to cool the battery 214. Furthermore, even after activating the cooling device 154, if the temperature of the battery 214 exceeds a second threshold (> first threshold), the ECU 100 may send a control command to the power transmission stand 10 to limit the transmission current. However, limiting the transmission current may result in a longer power transmission time. For example, when charging the battery 214, the time required to reach a fully charged state may be long.

[0036] These problems become particularly noticeable when the battery 214 deteriorates beyond its new condition, as its internal resistance increases and heat generation rises.

[0037] Figure 2 shows an example of the battery temperature change history during power transmission in a new and deteriorated battery 214. The vertical axis in Figure 2(A) and (B) both represents battery temperature. The horizontal axis in Figure 2(A) and (B) both represents time. LN1 in Figure 2(A) shows an example of the battery temperature change history of a new battery 214. LN2 in Figure 2(B) shows an example of the battery temperature change history of a deteriorated battery 214.

[0038] As shown in LN1 of Figure 2(A), when a new battery 214 is being charged and the cooling device 154 is not operating, the battery temperature increases in proportion to the passage of time.

[0039] At time T(0), when the temperature of the battery 214 exceeds the threshold t(0), the cooling device 154 activates, increasing the amount of heat dissipated and slowing down (decreasing) the rate of increase in battery temperature per unit time. Therefore, after the cooling device 154 is activated, the temperature of the battery 214 changes without exceeding the threshold t(1) for limiting the charging current, that is, without limiting the charging current.

[0040] On the other hand, as shown in LN2 of Figure 2(B), when the cooling device 154 is not operating while the degraded battery 214 is being charged, the battery temperature increases at a higher rate per unit time than when it is new, due to the increased heat generation caused by the increase in internal resistance.

[0041] At time T(1), when the temperature of the battery 214 exceeds the threshold t(0), the cooling device 154 activates, slowing down the rate of increase in battery temperature per unit time. However, because the amount of heat generated by the battery 214 has increased, the rate of increase is steeper than when it is new. Therefore, at time T(2) after the cooling device 154 has activated, the battery temperature exceeds the threshold t(1). When the battery temperature exceeds the threshold t(1), the charging current is limited, which reduces the amount of heat generated by the battery 214, slowing down the rate of increase in battery temperature per unit time. Subsequently, when the battery temperature falls below the threshold t(1), the limit on the charging current is released.

[0042] As the battery 214 deteriorates, its temperature is more likely to exceed the threshold t(1) than when it is new, and the transmission current is more likely to be limited. As a result, the time required for power transmission may also be extended.

[0043] Therefore, in this embodiment, if the transmission power was limited in the previous transmission control, the ECU 100 sets the first threshold value in the current transmission control to a value smaller than the first threshold value in the previous transmission control.

[0044] In this configuration, when the battery temperature increases in this transmission control, the battery 214 is cooled using the adjustment device 150 (specifically, the cooling device 154) at an earlier timing than in the previous transmission control. This prevents the temperature of the battery 214 from exceeding the second threshold. As a result, the transmission power is not limited, and the time required for power transmission is suppressed.

[0045] The following describes an example of processing performed by ECU100, with reference to Figure 3. Figure 3 is a flowchart showing an example of processing performed by ECU100.

[0046] In step 100 (hereinafter referred to as S), the ECU 100 determines whether the conditions for executing transmission control are met. The conditions for executing transmission control may include, for example, the condition that the connector 17 is connected to the inlet 220 and the condition that a control command requesting charging or discharging is output from the ECU 100 to the power transmission stand 10. If it is determined that the conditions for executing transmission control are met (YES in S100), the process moves to S102.

[0047] In S102, ECU100 acquires the limit history. The limit history includes information indicating whether or not the transmission current was limited in the previous transmission control. The limit history is stored in the memory of ECU100. ECU100 acquires the limit history by reading it from memory. The process then moves to S104.

[0048] In S104, the ECU100 determines whether the previous transmission control was performed without current limiting. Specifically, the ECU100 uses the acquired limiting history to determine whether the previous transmission control was performed without current limiting. If it is determined that the previous transmission control was performed without current limiting (YES in S104), the process moves to S106.

[0049] In S106, the ECU 100 determines whether the battery temperature is greater than the starting temperature t(0) at which cooling begins. The starting temperature t(0) is the threshold battery temperature at which the cooling device 154 begins to operate, and is, for example, a predetermined value. The starting temperature t(0) is adjusted through experiments, etc., so that it does not reach the limiting temperature t(1), which will be described later, at least in a new state. The starting temperature t(0) corresponds to the "first threshold," and the limiting temperature t(1) corresponds to the "second threshold." The ECU 100 obtains the battery temperature using the temperature sensor 106. If it is determined that the battery temperature is greater than the starting temperature t(0) (YES in S106), the process moves to S110. On the other hand, if it is determined that the previous transmission control was in a state with current limiting (NO in S104), the process moves to S108.

[0050] In S108, the ECU 100 determines whether the battery temperature is higher than the starting temperature t(2). The starting temperature t(2) is a threshold battery temperature at which the cooling device 154 starts operating, and is, for example, a predetermined value. The starting temperature t(2) is at least lower than the starting temperature t(0). The starting temperature t(2) is adjusted through experiments, etc., so that it does not reach the limiting temperature t(1), which will be described later, at least in a specific degradation state. If it is determined that the battery temperature is higher than the starting temperature t(2) (YES in S108), the process moves to S110.

[0051] In S110, ECU100 performs cooling control. Specifically, ECU100 activates the cooling device 154 to cool the battery 214. The process then moves to S112.

[0052] In S112, the ECU100 determines whether the battery temperature is greater than the limit temperature t(1). The limit temperature t(1) is the threshold temperature at which current limiting begins. The limit temperature t(1) is determined, for example, through experiments. If it is determined that the battery temperature is greater than the limit temperature t(1) (YES in S112), the process moves to S114.

[0053] In S114, the ECU100 implements current limiting. The ECU100 limits the current so that the magnitude of the transmission current during charging or discharging is less than or equal to a predetermined value. The predetermined value is, for example, a value such that the amount of heat dissipated by the battery 214 exceeds the amount of heat generated when the cooling device 154 is operating, and this is determined by experimentation or other means. The process then proceeds to S118. If it is determined that the battery temperature is below the limiting temperature t(1) (NO in S112), the process proceeds to S116.

[0054] In S116, ECU100 releases the current limit. If current limiting is not in place, ECU100 maintains that state. The process then proceeds to S118.

[0055] In S118, the ECU100 determines whether or not to terminate the cooling control. The ECU100 determines to terminate the cooling control, for example, when charging or discharging is completed, or when the battery temperature falls below the threshold temperature for terminating the cooling control. If it is determined that the cooling control should be terminated (YES in S118), the process moves to S120. If it is determined that the cooling control should not be terminated (NO in S118), the process returns to S112.

[0056] In S120, ECU100 terminates the cooling control. Specifically, ECU100 deactivates the cooling device 154. The process then moves to S122.

[0057] In S122, the ECU100 stores the control history. If current limiting was implemented in the current transmission control, the ECU100 stores information indicating that the transmission current was limited in the previous transmission control as part of the control history. If current limiting was not implemented in the current transmission control, the ECU100 stores information indicating that the transmission current was not limited in the previous transmission control as part of the control history. The process then terminates. This process is terminated if it is determined that the execution conditions for transmission control are not met (NO in S100), if the battery temperature is determined to be below the starting temperature t(0) (NO in S106), or if the battery temperature is determined to be below the starting temperature t(2) (NO in S108).

[0058] An example of the operation of the ECU100 based on the structure and flowchart described above will be explained with reference to Figure 4. Figure 4 shows an example of the change in battery temperature during the Nth and N+1th transmission control. The vertical axis in both Figure 4(A) and (B) represents the battery temperature. LN3 in Figure 4(A) shows an example of the battery temperature change history during the Nth transmission control. LN4 in Figure 4(B) shows an example of the battery temperature change history during the N+1th transmission control. It is also assumed that no current limiting was performed during the transmission control up to the Nth time.

[0059] As shown in LN3 of Figure 4(A), when the conditions for executing transmission control are met (YES in S100) and charging of the battery 214 begins, if the cooling device 154 is in a non-operating state, the battery temperature will increase in proportion to the passage of time until time T(3). When the Nth transmission control is started, the ECU 100 acquires the control history (S102) and determines that there was no current limit in the previous transmission control (YES in S104), and determines whether the battery temperature is greater than the starting temperature t(0) (S106).

[0060] At time T(3), if the battery temperature exceeds the starting temperature t(0) (YES in S106), cooling control is executed (S110). When the cooling device 154 is activated, the rate of increase in battery temperature slows down. However, if the battery 214 is in a degraded state, its internal resistance is higher than that of a new battery, increasing the amount of heat generated, so at time T(4), the battery temperature exceeds the limit temperature t(1). When the battery temperature exceeds the limit temperature t(1) (YES in S112), current limiting is implemented (S114). With cooling control continuing (NO in S118), the increase in heat generation is suppressed by the implementation of current limiting, so the battery temperature decreases at the point when the amount of heat dissipated by the battery 214 exceeds the amount of heat generated. At time T(5), when the battery temperature falls below the limit temperature t(1) (NO in S112), current limiting is released (S116). The period during which current limiting is implemented results in a longer time required for power transmission. Subsequently, if the conditions for terminating the cooling control are met, such as when the transmission control is completed (YES in S118), the cooling control is terminated (S120), and the limit history is stored (S122).

[0061] On the other hand, as shown in LN4 of Figure 4, when the conditions for executing transmission control are met again (YES in S100) and charging of the battery 214 is started, if the cooling device 154 is in a non-operating state, the battery temperature will increase in proportion to the passage of time until time T(6). When the N+1th transmission control is started, the ECU 100 acquires the control history (S102) and determines that the previous transmission control was in a state with current limiting (NO in S104), and determines whether the battery temperature is greater than the starting temperature t(2) (S108).

[0062] At time T(6), if the battery temperature exceeds the starting temperature t(2) (YES in S108), cooling control is executed (S110). When the cooling device 154 is activated, the rate of increase in battery temperature slows down. Furthermore, since the cooling device 154 is activated when the battery temperature is at the starting temperature t(2), which is lower than the starting temperature t(0), the battery temperature changes without exceeding the limiting temperature t(1) (NO in S112). Therefore, transmission control continues without current limiting being implemented (S116). As a result, the time required for power transmission is suppressed to be long. Subsequently, when the conditions for terminating the cooling control are met, such as when the transmission control ends (YES in S118), the cooling control is terminated (S120), and information indicating that current limiting was not implemented is stored as a limiting history (S122).

[0063] As described above, with the battery system 1 according to this embodiment, if current limiting was performed in the previous transmission control, in the current transmission control, the operation of the cooling device 154 is determined using a starting temperature t(2) that is lower than the starting temperature t(0). Therefore, the battery 214 can be cooled using the cooling device 154 at an earlier timing than in the previous transmission control. As a result, it is possible to suppress the temperature of the battery 214 from exceeding the limiting temperature t(1). Consequently, it is possible to avoid limiting the transmitted power, and thus suppress the time required for power transmission from becoming excessively long. Thus, it is possible to provide a battery system that cools the secondary battery so that the transmitted current is not limited during power transmission.

[0064] Furthermore, the ECU100 releases the current limit when the battery temperature falls below the limit temperature t(1) while the current limit is being applied, thus preventing the time required for power transmission from becoming excessively long.

[0065] The following describes variations. In the above-described embodiment, it was explained that if it was determined that there was a current limit in the previous transmission control, the operation of the cooling device 154 was determined using the starting temperature t(2). However, if the battery 214 is in a deteriorated state, the amount by which the threshold value of the starting temperature is lowered may be greater than when it is in a new state.

[0066] For example, the threshold starting temperature may be set to decrease as degradation progresses. The ECU 100 calculates, for example, the fully charged capacity of the battery 214 and calculates the degree of degradation (e.g., capacity retention rate) by comparing it with the initial value. The ECU 100 may also calculate the starting temperature according to the degree of degradation using a map or the like.

[0067] Figure 5 shows an example of the relationship between the starting temperature and the degree of degradation. The vertical axis in Figure 5 represents the starting temperature. The horizontal axis in Figure 5 represents the degree of degradation. LN5 in Figure 5 shows the change in the set starting temperature in response to the change in the degree of degradation.

[0068] Figure 5, section LN5, shows the relationship between the degree of degradation and the starting temperature when the degree of degradation and the starting temperature have a linear relationship. For example, if the degree of degradation is calculated to be D(0), the ECU100 sets the starting temperature t(3) based on the relationship shown in LN5 of Figure 5.

[0069] In this way, as the battery deteriorates, its internal resistance increases and the amount of heat generated increases. Therefore, by lowering the starting temperature more than when the battery is new, it is possible to prevent the temperature of the battery 214 from exceeding the limit temperature t(1). Note that the relationship between the degree of deterioration and the starting temperature is not limited to a linear relationship; it is sufficient if the starting temperature decreases as the degree of deterioration increases, and a nonlinear relationship is also acceptable.

[0070] Furthermore, in the above-described embodiment, if it was determined that there was a current limit in the previous transmission control, the operation of the cooling device 154 was determined using the starting temperature t(2). However, the ECU 100 may, for example, set the threshold value for the starting temperature in the current transmission control to a value smaller than the starting temperature t(0) in the previous transmission control, using at least the amount by which the battery temperature exceeded the limiting temperature t(1) in the previous transmission control as the reduction amount.

[0071] In this way, the threshold temperature for the starting temperature in the current transmission control is set by reducing the amount by which the battery temperature exceeded the limit temperature t(1) in the previous transmission control, thereby reliably preventing the battery temperature from exceeding the limit temperature t(1).

[0072] Furthermore, in the above-described embodiment, if it was determined that there was a current limit in the previous transmission control, the operation of the cooling device 154 was determined using a threshold value lower than the starting temperature used in the previous transmission control as the starting temperature in the current transmission control. However, the operation of the cooling device 154 may also be determined using a threshold value lower than the starting temperature used in the previous transmission control in subsequent transmission control cycles, or the operation of the cooling device 154 may be determined using a threshold value lower than the starting temperature used in the previous transmission control cycle for a predetermined number of subsequent transmission control cycles.

[0073] Furthermore, the above-mentioned modifications may be implemented by combining all or part of them as appropriate. The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0074] 1 Battery system, 10 Power transmission stand, 13 Communication unit, 14 Control unit, 15 Transmission unit, 16 Cable, 17 Connector, 100 ECU, 102 Voltage sensor, 104 Current sensor, 106 Temperature sensor, 150 Regulator, 152 Heating device, 154 Cooling device, 200 Vehicle, 214 Battery, 216 Inverter, 218 MG, 220 Inlet, 222 Drive wheels, 400 System power supply.

Claims

1. Rechargeable batteries and A transmission system that performs power transmission to and from the aforementioned secondary battery, A temperature control device for adjusting the temperature of the secondary battery, The system includes a control device that controls the adjustment device to cool the secondary battery if the temperature of the secondary battery exceeds a first threshold during power transmission control, The control device is When the temperature of the secondary battery exceeds a second threshold that is greater than the first threshold, the transmission power transmitted between the secondary battery and the transmission system is limited. A battery system that, if the transmission power was limited in the previous transmission control, sets the first threshold value in the current transmission control to a value smaller than the first threshold value in the previous transmission control.

2. The battery system according to claim 1, wherein the control device reduces the amount by which the first threshold is lowered when the secondary battery is in a deteriorated state compared to when it is in a new state.

3. The battery system according to claim 1, wherein the control device sets the first threshold value in the current transmission control to a value smaller than the first threshold value in the previous transmission control, by reducing the amount by which the temperature of the secondary battery exceeded the second threshold value in the previous transmission control.

4. The battery system according to any one of claims 1 to 3, wherein the control device releases the restriction on the transmitted power when the temperature of the secondary battery falls below a second threshold while the power being transmitted is being restricted.

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