Battery cooling system

Abstract

We provide a battery cooling system that can efficiently cool the batteries of a vehicle. [Solution] The battery cooling system comprises a cooling device configured to cool the battery and a control device that controls the cooling device. The control device 200 includes a target temperature prediction unit 202 that predicts the target temperature of the vehicle's battery based on the type of road the vehicle travels on and the ambient temperature of the location where the vehicle travels, a cooling level determination unit 203 that determines the cooling level of the cooling device based on the target temperature, and a cooling control unit 204 that controls the cooling capacity of the cooling device based on the cooling level of the cooling device.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a technique for estimating the battery temperature reached based on the heat dissipation amount by the vehicle running wind and the battery heat generation amount, and operating a battery cooling device to cool the battery when the battery temperature reached is higher than the cooling start temperature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the patent document, since it is not set how much to cool according to the battery temperature reached, it is difficult to efficiently cool the battery.

[0005] Therefore, an object of the present disclosure is to provide a battery cooling system capable of efficiently cooling the battery of a vehicle.

Means for Solving the Problems

[0006] The battery cooling system of the present disclosure includes a cooling device configured to cool the battery of a vehicle, and a control device that controls the cooling device. The control device includes a prediction unit that predicts the battery temperature reached based on the road type on which the vehicle travels and the air temperature at the vehicle's traveling location, a cooling level determination unit that determines the cooling level of the cooling device based on the temperature reached, and a cooling control unit that controls the cooling capacity of the cooling device based on the cooling level of the cooling device.

[0007] According to the above configuration, the cooling level is determined based on the predicted target temperature, which is determined based on the type of road the vehicle travels on and the ambient temperature at the vehicle's location, thus enabling efficient cooling of the battery. [Effects of the Invention]

[0008] According to this disclosure, the battery can be cooled efficiently. [Brief explanation of the drawing]

[0009] [Figure 1] This is a flowchart illustrating the battery cooling procedure for the vehicle according to the first embodiment. [Figure 2] This figure shows an example of the configuration of the cooling device 40. [Figure 3] This is a diagram showing the configuration of the cooling control device 200. [Figure 4] This diagram illustrates the expected temperature and battery cooling level. [Figure 5] This is a flowchart illustrating the cooling control procedure for the battery 21 of the vehicle according to the first embodiment. [Figure 6] This figure shows an example of a target temperature frequency distribution. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. Figure 1 shows an example of the overall configuration of a vehicle equipped with a battery cooling system according to an embodiment of the present disclosure. Vehicle 1 is, for example, a plug-in hybrid vehicle configured to be able to be charged by power supplied from outside Vehicle 1 (plug-in charging). However, Vehicle 1 may be any vehicle equipped with a battery for driving, and may be a normal hybrid vehicle that does not support plug-in charging. Vehicle 1 may be an electric vehicle or a fuel cell vehicle.

[0011] Vehicle 1 comprises a running unit 10, a battery pack 20, a charging unit 30, a cooling system 40, an air conditioning path 50, and an ECU (Electronic Control Unit) 100. The running unit 10 includes motor generators 11 and 12, a PCU 13, an engine 14, a power split device 15, and drive wheels 16. The battery pack 20 includes a battery 21 and a current sensor 24. The charging unit 30 includes an inlet 31, an AC / DC converter 32, and a charge relay (CHR) 33.

[0012] Each of the motor generators 11 and 12 is an AC rotating electric machine, for example, a three-phase AC synchronous motor with permanent magnets embedded in the rotor. Motor generator 11 is mainly used as a generator driven by engine 14 via power splitter 15. The power generated by motor generator 11 is supplied to motor generator 12 or battery 21 via PCU 13. Motor generator 11 can also crank engine 14.

[0013] The motor-generator 12 primarily operates as an electric motor, driving the drive wheels 16. The motor-generator 12 is powered by at least one of the power from the battery 21 and the power generated by the motor-generator 11. The driving force of the motor-generator 12 is transmitted to the drive shaft. On the other hand, when the vehicle 1 is braking or when acceleration is reduced on a downhill slope, the motor-generator 12 operates as a generator to perform regenerative power generation. The power generated by the motor-generator 12 is supplied to the battery 21 via the PCU 13.

[0014] The PCU13 is configured to perform bidirectional power conversion between the battery 21 and the motor generators 11 and 12, or between the motor generators 11 and 12, in accordance with control commands from the ECU100.

[0015] The engine 14 outputs power by converting the combustion energy generated when a mixture of air and fuel burns into the kinetic energy of a moving element (such as a piston or a rotor).

[0016] The power split device 15 is, for example, a planetary gear device. Although not shown in any figure, the power split device 15 includes a sun gear, a ring gear, pinion gears, and a carrier. The carrier is connected to the engine 14. The sun gear is connected to the motor generator 11. The ring gear is connected to the motor generator 12 and the drive wheels 16 via a drive shaft. The pinion gears mesh with the sun gear and the ring gear. The carrier holds the pinion gears so that they can rotate and revolve freely.

[0017] The battery 21 is a battery pack including a plurality (typically dozens to hundreds) of cells. Each cell is a secondary battery such as a lithium-ion battery or a nickel-hydrogen battery. The battery 21 stores electric power for driving the motor generators 11 and 12 and supplies the electric power to the motor generators 11 and 12 through the PCU 13. Also, the battery 21 is charged by receiving the generated electric power through the PCU 13 when the motor generators 11 and 12 generate power.

[0018] The current sensor 24 detects the current I input to and output from the battery 21 via a power line that electrically connects the battery 21 and the PCU 13, and outputs the detection result to the ECU 100.

[0019] The inlet 31 is configured to be able to insert a charging connector (not shown) of a charging cable with a mechanical connection such as fitting.

[0020] The AC / DC converter 32 is electrically connected between the inlet 31 and the charging relay 33. The AC / DC converter 32 converts the alternating current power supplied from an external power source (such as a charging stand) through the inlet 31 into direct current power according to a control command from the ECU 100. Instead of or in addition to the AC / DC converter 32, a DC / DC converter may be provided.

[0021] The charging relay 33 is electrically connected between the AC / DC converter 32 and the battery pack 20. When the charging relay 33 is closed according to a control command from the ECU 100, power transmission between the inlet 31 and the battery pack 20 becomes possible.

[0022] The cooling device 40 is configured to cool the battery pack 20 according to a control command from the ECU 100.

[0023] The ECU 100 includes a processor 101 such as a CPU (Central Processing Unit), a memory 102 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an I / O port (not shown) for inputting and outputting various signals. The ECU 100 controls the vehicle 1 to a desired state based on signals received from each sensor and programs and maps stored in the memory 102. As the main control executed by the ECU 100 in the present embodiment, cooling control of the battery 21 by the cooling device 40 can be mentioned. This cooling control will be described in detail later. The ECU 100 corresponds to the "control device" according to the present disclosure. The ECU 100 may be configured by being divided into a plurality of ECUs for each function.

[0024] FIG. 2 is a diagram showing an example of the configuration of the cooling device 40. In FIG. 2, in addition to the cooling device 40, the battery pack 20, the PCU 13 and the ECU 100 are also shown. The cooling device 40 includes a refrigerant circuit 41, a chiller 42, and a coolant circuit 43.

[0025] The refrigerant circuit 41 is a circuit for adjusting the temperature of the refrigerant (liquid-phase refrigerant or gas-phase refrigerant) circulating in the coolant circuit 43. The flow direction of the refrigerant is represented by an arrow. The refrigerant circuit 41 has, for example, a configuration equivalent to a general heat pump system, and includes a compressor 71, a condenser 72, expansion valves 73, 74, and an evaporator 75. Hereinafter, the case during the cooling operation in the vehicle interior will be described as an example.

[0026] The compressor 71 compresses the gaseous refrigerant circulating in the refrigerant circuit 41. The gaseous refrigerant, compressed to high temperature and pressure by the compressor 71, is sent to the condenser 72.

[0027] The condenser 72 condenses the gaseous refrigerant into a liquid refrigerant by releasing heat from the gaseous refrigerant, which has been compressed by the compressor 71 to become high temperature and high pressure.

[0028] The expansion valve 73 reduces the pressure of the liquid phase refrigerant by expanding the high-pressure liquid phase refrigerant compressed by the condenser 72. The liquid phase refrigerant reduced in pressure by the expansion valve 73 is sent to the evaporator 75.

[0029] The expansion valve 74, like the expansion valve 73, depressurizes the liquid phase refrigerant by expanding the high-pressure liquid phase refrigerant compressed by the condenser 72. The liquid phase refrigerant depressurized by the expansion valve 74 is sent to the chiller 42.

[0030] The evaporator 75 exchanges heat between the air blown onto it and the liquid refrigerant. This adjusts the temperature of the air blown onto the evaporator 75 (cooling it during cooling operation). The liquid refrigerant absorbs heat from the surrounding air and vaporizes, changing into a gaseous refrigerant. This gaseous refrigerant returns to the compressor 71. The switching between heating and cooling operations of the evaporator 75 is achieved by switching the output direction of the compressor 71.

[0031] The chiller 42 performs heat exchange between the refrigerant circulating in the refrigerant circuit 41 and the coolant circulating in the coolant circuit 43. More specifically, the liquid phase refrigerant, which has been depressurized by the expansion valve 74, evaporates within the chiller 42, thereby removing heat from the coolant circulating in the coolant circuit 43. This cools the coolant circulating in the coolant circuit 43.

[0032] The coolant circuit 43 includes a cooling path 8, a radiator 91, a reserve tank (R / T) 92, a water pump (W / P) 93, an oil cooler (O / C) 94, a water pump 95, and a five-way valve 96.

[0033] The cooling path 8 is a piping system that constitutes the flow path for the coolant. The coolant is, for example, LLC (Long Life Coolant) containing ethylene glycol. When the water pumps 93 and 95 are driven in the coolant circuit 43, the coolant supplied from the water pumps 93 and 95 passes through the five-way valve 96 to the battery pack 20, PCU 13, or radiator 91, etc., and then returns to the water pumps 93 and 95. This causes the coolant to circulate within the cooling path 8. The direction of coolant circulation is indicated by an arrow. The cooling path 8 includes the first path 81 to the fifth path 85.

[0034] The first path 81 connects the five-way valve 96 and the reserve tank 92. The radiator 91 is connected to the first path 81.

[0035] The second path 82 connects the five-way valve 96 to the reserve tank 92. No equipment such as the radiator 91 is connected to the second path 82, and it is configured to bypass the radiator 91. The first path 81 and the second path 82 are connected within the reserve tank 92.

[0036] The third route 83 connects the second route 82 upstream (before) the connection point to the reserve tank 92 to the five-way valve 96. The water pump 93, PCU 13, and oil cooler 94 are connected to the third route 83.

[0037] The fourth path 84 connects the five-way valve 96 to the reserve tank 92. The electric heater 23, the junction box 22, and the battery 21 are connected to the fourth path 84. In other words, in this example, the coolant flowing through the fourth path 84 is used in common for cooling both the junction box 22 and the battery 21. However, the cooling path 8 may be configured such that the coolant for cooling the junction box 22 and the coolant for cooling the battery 21 flow through separate paths.

[0038] The fifth pathway 85 connects the reserve tank 92 and the five-way valve 96. The water pump 95 and chiller 42 are connected to the fifth pathway 85. The fourth pathway 84 and the fifth pathway 85 are connected within the reserve tank 92.

[0039] The radiator 91 cools the coolant by exchanging heat between the coolant and the outside air of the vehicle 1. The reserve tank 92 stores the coolant in the cooling passage 8.

[0040] The water pump 93 is an electric water pump that discharges coolant according to control commands from the ECU 100. The PCU 13 is connected downstream of the water pump 93 in the third path 83. The PCU 13 can be cooled by the coolant discharged from the water pump 93.

[0041] The oil cooler 94 is connected downstream of the PCU 13 in the third path 83. Although not shown in the diagram, an electric oil pump (EOP) is connected to the oil cooler 94. The oil cooler 94 cools the transaxle of the travel unit 10 by exchanging heat between the coolant flowing through the third path 83 and the oil cooler 94.

[0042] The water pump 95 is an electric water pump that discharges coolant according to control commands from the ECU 100. Upstream of the fifth path 85 to which the water pump 95 is connected, the fourth path 84 is connected. By driving the water pump 93, the electric heater 23, junction box 22, and battery 21 located in the fourth path 84 can be cooled.

[0043] The five-way valve 96 is configured to switch the connections of the cooling paths 8 according to control commands from the ECU 100 so that coolant input from at least one of the third path 83 and the fifth path 85 is output to at least one of the second path 82, the fourth path 84, and the first path 81. For example, a "battery cooling circuit" (see thick solid line and arrow AR1) can be formed by switching the connections of the cooling paths 8 so that coolant input from the fifth path 85 is output to the fourth path 84.

[0044] The above is an example of a cooling device 40. The cooling device 40 may be a water-cooled or air-cooled device of any other type.

[0045] The ECU 100 includes a cooling control device 200 that controls the cooling device 40. Figure 3 is a diagram showing the configuration of the cooling control device 200. Figure 4 is a diagram illustrating the expected target temperature and battery cooling level. The cooling control device 200 and the cooling device 40 constitute the cooling system 300.

[0046] The cooling control device 200 includes a data acquisition unit 201, a target temperature prediction unit 202, a cooling level determination unit 203, and a cooling control unit 204.

[0047] The data acquisition unit 201 acquires the type of road the vehicle will be traveling on at a certain time in the future from navigation information, and acquires temperature information for the vehicle's location at a certain time in the future from navigation (network) information.

[0048] The temperature prediction unit 202 predicts the temperature to be reached of the vehicle's battery 21 at a certain point in the future, based on the type of road the vehicle will be traveling on at a certain point in the future and the temperature information of the vehicle's location at a certain point in the future. As shown in the example in Figure 4, the range of temperature to be reached of the battery 21 is predicted based on whether the road type at a certain point in the future is a highway, a private road, or another type of road, and the range of temperatures of the location at a certain point in the future. The range of temperature to be reached can be, for example, N levels.

[0049] The cooling level determination unit 203 determines the cooling level LV of the cooling device 40 based on the predicted target temperature. The cooling level LV can be, for example, in M ​​stages. For example, the cooling level determination unit 203 may set the cooling level LV such that the temperature of the battery 21 reaches the target temperature (for example, 25°C or lower). Alternatively, the cooling level determination unit 203 may set the cooling level LV such that the temperature frequency distribution of the battery 21 becomes the target temperature frequency distribution.

[0050] Figure 6 shows an example of a target temperature frequency distribution. Temperature range 1 is defined as the range of 95% or more and less than 100% of temperature A. Temperature range 2 is defined as the range of 90% or more and less than 95% of temperature A. Temperature range 3 is defined as the range of 80% or more and less than 90% of temperature A. Temperature range 4 is defined as the range of 60% or more and less than 80% of temperature A. Temperature range 5 is defined as the range of less than 60% of temperature A. Temperature A is a predetermined temperature, for example, the temperature at which a known cooling device will activate its cooling operation. In the target temperature distribution, the frequency ratio of temperature range 1 is less than 10%, the frequency ratio of temperature range 2 is higher than the frequency ratio of temperature range 1, the frequency ratio of temperature range 3 is higher than the frequency ratio of temperature range 2, and the frequency ratio of temperature range 4 is 40% or more. The aim is to further prevent degradation by reducing the frequency even in the relatively high-temperature region (distributing it as much as possible towards the lower temperature side).

[0051] The cooling control unit 204 controls the cooling capacity of the cooling device 40 based on the cooling level LV of the cooling device 40.

[0052] The higher the cooling level LV, the greater the cooling capacity of the cooling device 40. For example, the higher the cooling level LV, the higher the frequency of the compressor 71. Alternatively, if the cooling device 40 is an air-cooled cooling device, the higher the cooling level LV, the greater the cooling airflow from the blower. If the cooling device 40 is a water-cooled cooling device, the higher the cooling level LV, the greater the output of the cooling mechanism.

[0053] The cooling control unit 204 may control the cooling device 40 with a cooling pattern at a determined cooling level LV to bring the battery 21 to a target temperature (for example, 25°C or lower). The cooling control unit 204 may also control the cooling device 40 with a cooling pattern at a determined cooling level LV to bring the target temperature frequency distribution of the battery 21 to a predetermined frequency distribution. For example, the cooling control unit 204 measures the temperature of the battery 21 at predetermined time intervals, updates the histogram (temperature frequency distribution), increases the cooling capacity if the current temperature frequency distribution is shifted to a higher temperature than the standard temperature frequency distribution, and decreases the cooling capacity if it is shifted to a lower temperature than the target temperature frequency distribution.

[0054] Figure 5 is a flowchart showing the cooling control procedure for the battery 21 of the vehicle in the first embodiment.

[0055] In step S101, the data acquisition unit 201 acquires the type of road the vehicle will be traveling on at a certain time in the future from the navigation information.

[0056] In step S102, the data acquisition unit 201 acquires temperature information for the vehicle's location at a future time from navigation (network) information.

[0057] In step S103, the temperature prediction unit 202 predicts the temperature to be reached of the vehicle's battery 21 at a future time, based on the type of road the vehicle will travel on at a certain future time and the ambient temperature of the vehicle's location at that future time. For example, the temperature to be reached of the battery 21 can be predicted in N steps.

[0058] In step S104, the cooling level determination unit 203 determines the cooling level LV of the battery 21 based on the temperature reached by the battery 21. For example, the cooling level LV of the battery 21 can be set to M levels.

[0059] In step S105, the cooling control unit 204 controls the cooling device 40 so that its cooling capacity corresponds to the set cooling level LV of the battery 21.

[0060] In step S106, if a predetermined condition is met, the process proceeds to step S107. The predetermined condition is that the temperature of the battery 21 becomes the target temperature (for example, 25°C or lower), or that the temperature frequency distribution of the battery 21 becomes the target temperature frequency distribution.

[0061] In step S107, the cooling control unit 204 stops controlling the cooling device 40 according to the set cooling level LV of the battery 21.

[0062] As described above, according to this embodiment, the battery can be efficiently cooled by predicting the temperature reached by the battery based on the type of road and ambient temperature of the vehicle's location, and by cooling the battery at a cooling level based on the predicted temperature reached by the battery.

[0063] Because onboard batteries degrade when exposed to high temperatures, the cell temperature is monitored and cooled when it exceeds a certain temperature. On the other hand, a high frequency of temperatures in the slightly high-temperature range, even if it does not exceed the certain temperature, also leads to degradation. In this embodiment, in order to reduce the frequency of temperatures in the slightly high-temperature range, the battery temperature is accurately predicted from the road surface and ambient temperature, and the cooling is adjusted in stages according to the predicted target battery temperature. As a result, the battery temperature is kept below a certain temperature or at a temperature that avoids high temperatures, thereby suppressing degradation.

[0064] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0065] 8 Cooling path, 10 Drive unit, 11,12 Motor generator, 14 Engine, 15 Power split device, 16 Drive wheels, 20 Battery pack, 21 Battery, 22 Junction box, 23 Electric heater, 24 Current sensor, 30 Charging unit, 31 Inlet, 32 Converter, 33 Charging relay, 40 Cooling system, 41 Refrigerant circuit, 42 Chiller, 43 Coolant circuit, 50 Air conditioning path, 71 Compressor, 72 Condenser, 73,74 Expansion valve, 75 Evaporator, 81 First path, 82 Second path, 83 Third path, 84 Fourth path, 85 Fifth path, 91 Radiator, 92 Reserve tank, 93,95 Water pump, 94 Oil cooler, 96 Five-way valve, 101 Processor, 102 Memory, 200 Cooling control device, 201 Data acquisition unit, 202 Temperature prediction unit, 203 Cooling level determination unit, 204 Cooling control unit, 300 Cooling system.

Claims

1. A cooling device configured to cool the vehicle's battery, The system includes a control device for controlling the cooling device, The control device is A prediction unit predicts the temperature to be reached of the battery based on the type of road the vehicle travels on and the temperature of the location where the vehicle travels. A cooling level determination unit that determines the cooling level of the cooling device based on the temperature reached, A battery cooling system comprising: a cooling control unit that controls the cooling capacity of the cooling device based on the cooling level of the cooling device.

2. The battery cooling system according to claim 1, wherein the cooling control unit controls the temperature of the battery to be below a predetermined temperature.

3. The battery cooling system according to claim 1, wherein the cooling control unit controls the frequency distribution of the battery temperature to a predetermined frequency distribution.

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