Battery cooling system

Abstract

The invention provides a battery cooling system capable of effectively cooling a battery of a vehicle. A battery cooling system is provided with: a cooling device configured to cool a battery; and a control device for controlling the cooling device. The control device includes: an arrival temperature prediction unit that predicts an arrival temperature of a battery of the vehicle on the basis of a road type on which the vehicle travels and an air temperature of a travel location of the vehicle; a cooling level determination unit that determines the cooling level of the cooling device on the basis of the reached temperature; and a cooling control unit that controls the cooling capacity of the cooling device in accordance with the cooling level of the cooling device.

Description

Technical Field

[0001] This invention relates to a battery cooling system. Background Technology

[0002] Patent document 1 discloses a technology that estimates the battery temperature based on the heat dissipation caused by the wind during vehicle operation and the heat generated by the battery. When the battery temperature is higher than the cooling start temperature, the battery cooling device is activated to cool the battery.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-126785 Summary of the Invention

[0004] The patent literature does not specify how much cooling should be applied based on the battery's temperature, making it difficult to effectively cool the battery.

[0005] Therefore, the object of the present invention is to provide a battery cooling system that can effectively cool the battery of a vehicle.

[0006] The battery cooling system of the present invention includes: a cooling device configured to cool a vehicle battery; and a control device for controlling the cooling device. The control device includes: a temperature prediction unit for predicting the temperature of the battery based on the type of road in which the vehicle is traveling and the ambient temperature of the location where the vehicle is traveling; a cooling level determination unit for determining the cooling level of the cooling device based on the temperature of the battery; and a cooling control unit for controlling the cooling capacity of the cooling device based on the cooling level of the cooling device.

[0007] Based on the above structure, the cooling level is determined according to the predicted arrival temperature based on the road type and the ambient temperature of the vehicle's location, thus effectively cooling the battery.

[0008] Invention Effects

[0009] According to the present invention, the battery can be cooled effectively. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating the cooling steps of the battery in the vehicle according to the first embodiment.

[0011] Figure 2 This is a diagram showing an example of the structure of the cooling device 40.

[0012] Figure 3 This is a diagram showing the structure of the cooling control device 200.

[0013] Figure 4 It is a diagram used to illustrate the expected temperature and the battery cooling level.

[0014] Figure 5This is a flowchart illustrating the cooling control steps of the battery 21 of the vehicle according to the first embodiment.

[0015] Figure 6 This is a graph representing an example of the frequency distribution of a target temperature. Detailed Implementation

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] Figure 1 This diagram illustrates an example of the overall structure of a vehicle equipped with the battery cooling system according to an embodiment of the present invention. Vehicle 1 is, for example, a plug-in hybrid vehicle capable of being charged (plug-in charging) by electricity supplied from an external source. Vehicle 1 can be any vehicle equipped with a driving battery, or it can be a conventional hybrid vehicle that does not support plug-in charging. Vehicle 1 can also be a pure electric vehicle or a fuel cell vehicle.

[0018] Vehicle 1 includes: a driving unit 10; a battery pack 20; a charging unit 30; a cooling system 40; an air conditioning duct 50; and an electronic control unit (ECU) 100. The driving unit 10 includes: a motor generator 11 and 12; a PCU 13; an engine 14; a power splitter 15; and drive wheels 16. The battery pack 20 includes a battery 21 and a current sensor 24. The charging unit 30 includes: an air intake 31; an AC / DC converter 32; and a charging relay (CHR) 33.

[0019] Both motor generators 11 and 12 are AC rotating motors, such as three-phase AC synchronous motors with permanent magnets embedded in the rotor. Motor generator 11 is mainly used as a generator driven by engine 14 via power splitting device 15. The electricity generated by motor generator 11 is supplied to motor generator 12 or battery 21 via PCU 13. Furthermore, motor generator 11 can also start engine 14.

[0020] The motor-generator 12 primarily functions as an electric motor, driving the drive wheel 16. The motor-generator 12 is driven by receiving 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 brakes or decelerates on a downhill slope, the motor-generator 12 operates as a generator, performing regenerative power generation. The power generated by the motor-generator 12 is supplied to the battery 21 via the PCU 13.

[0021] PCU13 is configured to perform bidirectional power conversion between battery 21 and motor generator 11 and motor generator 12, or between motor generator 11 and motor generator 12, according to control commands from ECU100.

[0022] Engine 14 outputs power by converting the combustion energy generated when the air-fuel mixture is burned into the kinetic energy of the moving parts (piston or rotor, etc.).

[0023] The power splitting device 15 is, for example, a planetary gear system. Although not shown, the power splitting device 15 includes a sun gear, a ring gear, a pinion, and a planet carrier. The planet 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 wheel 16 via a drive shaft. The pinion meshes with the sun gear and the ring gear. The planet carrier holds the pinion in a free-rotating and revolving manner.

[0024] Battery 21 is a battery pack comprising multiple (typically dozens to hundreds) battery cells. Each battery cell is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. Battery 21 stores electricity for driving motor generators 11 and 12, and supplies electricity to motor generators 11 and 12 via PCU 13. Furthermore, battery 21 is charged by receiving generated electricity through PCU 13 when motor generators 11 and 12 are generating electricity.

[0025] The current sensor 24 detects the current I input / output to the battery 21 via the power line that electrically connects the battery 21 to the PCU13, and outputs the detection result to the ECU100.

[0026] The air inlet 31 is configured as a charging connector (not shown) into which a charging cable can be inserted, accompanied by mechanical connections such as mating.

[0027] The AC / DC converter 32 is electrically connected between the air intake 31 and the charging relay 33. The AC / DC converter 32 converts AC power supplied from an external power source (such as a charging bracket) via the air intake 31 into DC power according to control commands from the ECU 100. Alternatively, a DC / DC converter may be installed in place of the AC / DC converter 32 or in a different configuration.

[0028] 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 the control command from the ECU 100, it becomes a state in which power can be transferred between the air intake 31 and the battery pack 20.

[0029] The cooling device 40 is configured to cool the battery pack 20 according to control commands from the ECU 100.

[0030] The battery ECU 100 includes a processor 101 such as a central processing unit (CPU), a memory 102 such as a read-only memory (ROM) and a random access memory (RAM), and various I / O ports for signal input and output (not shown). The ECU 100 controls the vehicle 1 to a desired state based on signals received from various sensors and programs and maps stored in the memory 102. In this embodiment, the main control performed by the ECU 100 is the cooling control of the battery 21 based on the cooling device 40. This cooling control will be described in detail later. The ECU 100 is equivalent to the "control device" involved in this invention. The ECU 100 can also be configured by dividing it into multiple ECUs for each function.

[0031] Figure 2 This is a diagram illustrating an example of the structure of the cooling device 40. Figure 2 In addition to the cooling device 40, the battery pack 20, PCU 13, and ECU 100 are also shown. The cooling device 40 includes a refrigerant circuit 41, a cooler 42, and a coolant circuit 43.

[0032] Refrigerant circuit 41 is a circuit used to adjust the temperature of the refrigerant (liquid-phase or gaseous-phase refrigerant) circulating in coolant circuit 43. Arrows indicate the direction of refrigerant flow. Refrigerant circuit 41 has, for example, the same structure as a typical heat pump system, including compressor 71, condenser 72, expansion valves 73 and 74, and evaporator 75. The following description uses in-vehicle cooling operation as an example.

[0033] Compressor 71 compresses the gaseous refrigerant circulating in refrigerant circuit 41. The gaseous refrigerant, compressed by compressor 71 into a high-temperature, high-pressure gaseous refrigerant, is sent to condenser 72.

[0034] 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 a high-temperature and high-pressure gaseous refrigerant.

[0035] Expansion valve 73 reduces the pressure of the liquid refrigerant by expanding the high-pressure liquid refrigerant compressed by condenser 72. The liquid refrigerant reduced by expansion valve 73 is then sent to evaporator 75.

[0036] Similar to expansion valve 73, expansion valve 74 depressurizes the liquid refrigerant by expanding the high-pressure liquid refrigerant compressed by condenser 72. The depressurized liquid refrigerant is then sent to cooler 42.

[0037] The evaporator 75 exchanges heat between the air blown into it and the liquid refrigerant. This adjusts (cools during cooling operation) the temperature of the air blown into the evaporator 75. The liquid refrigerant vaporizes by absorbing heat from the surrounding air, becoming a gaseous refrigerant. This gaseous refrigerant returns to the compressor 71. Furthermore, the switching between heating and cooling operations of the evaporator 75 is achieved by switching the output direction of the compressor 71.

[0038] Cooler 42 facilitates heat exchange between the refrigerant circulating in refrigerant circuit 41 and the coolant circulating in coolant circuit 43. More specifically, the liquid refrigerant, depressurized by expansion valve 74, evaporates within cooler 42, thereby removing heat from the coolant circulating in coolant circuit 43. This cools the coolant circulating in coolant circuit 43.

[0039] The coolant circuit 43 includes a cooling path 8, a radiator 91, a reservoir (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.

[0040] Cooling path 8 is the piping that forms the flow path for the coolant. The coolant is, for example, a long-life coolant (LLC) containing ethylene glycol. If water pumps 93 and 95 are driven in coolant circuit 43, the coolant supplied from water pumps 93 and 95 returns to water pumps 93 and 95 after passing through battery pack 20, PCU 13, or radiator 91 via five-way valve 96. Thus, the coolant circulates within cooling path 8. The direction of coolant circulation is indicated by arrows. Cooling path 8 includes paths 1 through 5, 81 and 85.

[0041] The first path 81 connects the five-way valve 96 to the liquid storage tank 92. A radiator 91 is connected to the first path 81.

[0042] The second path 82 connects the five-way valve 96 to the liquid storage 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 liquid storage tank 92.

[0043] The third path 83 connects to the second path 82 upstream (near the front) of the connection point to the liquid storage tank 92, and to the five-way valve 96. A water pump 93, PCU13, and oil cooler 94 are connected to the third path 83.

[0044] The fourth path 84 connects the five-way valve 96 to the liquid storage tank 92. An electric heater 23, a junction box 22, and a battery 21 are connected to the fourth path 84. That is, in this example, the coolant flowing through the fourth path 84 is used to cool both the junction box 22 and the battery 21. However, the cooling path 8 can also be configured such that the coolant cooling the junction box 22 and the coolant cooling the battery 21 flow on separate paths.

[0045] The fifth path 85 connects the liquid storage tank 92 to the five-way valve 96. A water pump 95 and a cooler 42 are connected to the fifth path 85. The fourth path 84 and the fifth path 85 are connected inside the liquid storage tank 92.

[0046] The radiator 91 cools the coolant by exchanging heat between the outside air and the coolant in the vehicle 1. The reservoir 92 stores the coolant within the cooling path 8.

[0047] Water pump 93 is an electric water pump that discharges coolant according to control commands from ECU 100. In the third path 83, PCU 13 is connected downstream of water pump 93. PCU 13 can be cooled by the coolant discharged from water pump 93.

[0048] Oil cooler 94 is connected in the third path 83 at a position further downstream than PCU13. Although not shown, an electric oil pump (EOP) is connected to oil cooler 94. Oil cooler 94 cools the drive shaft of travel unit 10 by exchanging heat between the coolant flowing in the third path 83 and oil cooler 94.

[0049] Water pump 95 is an electric water pump that discharges coolant according to control commands from ECU 100. A fourth path 84 is connected upstream of the fifth path 85, which is connected to water pump 95. By driving water pump 93, the electric heater 23, junction box 22, and battery 21 located in the fourth path 84 can be cooled.

[0050] The five-way valve 96 is configured to switch the connection of the cooling path 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, by switching the connection of the cooling path 8 so that coolant input from the fifth path 85 is output to the fourth path 84, a "battery cooling circuit" can be formed (refer to the thick solid line and arrow AR1).

[0051] The above is one example of the cooling device 40. The cooling device 40 can also be other types of cooling devices, such as water-cooled or air-cooled devices.

[0052] The ECU100 is equipped with a cooling control device 200 that controls the cooling device 40. Figure 3 This is a diagram showing the structure of the cooling control device 200. Figure 4 This is a diagram used to illustrate the expected temperature and battery cooling level. The cooling system 300 consists of the cooling control device 200 and the cooling device 40.

[0053] The cooling control device 200 includes a data acquisition unit 201, a temperature prediction unit 202, a cooling level determination unit 203, and a cooling control unit 204.

[0054] The data acquisition unit 201 obtains the road type of the vehicle at a future time from the navigation information, and obtains the temperature information of the vehicle's driving location at a future time from the navigation (net) information.

[0055] The arrival temperature prediction unit 202 predicts the arrival temperature of the vehicle's battery 21 at a future time based on the road type and the ambient temperature information of the vehicle's location at a future time. For example... Figure 4 The example shown predicts the range of the arrival temperature of battery 21 based on the road type at a future time (whether it is a highway, a dedicated road, or another type of road) and the range of temperatures at the future travel location. The range of arrival temperatures can, for example, be set to N stages.

[0056] The cooling level determination unit 203 determines the cooling level LV of the cooling device 40 based on the predicted arrival temperature. The cooling level LV can be set to, for example, stage M. For example, the cooling level determination unit 203 can set the cooling level LV to a target temperature (e.g., below 25°C) for the temperature of the battery 21. Alternatively, the cooling level determination unit 203 can set the cooling level LV to make the temperature frequency distribution of the battery 21 match the target temperature frequency distribution.

[0057] Figure 6This is a diagram illustrating an example of the frequency distribution of a target temperature. Temperature region 1 is defined as the range of 95% to 100% of temperature A. Temperature region 2 is defined as the range of 90% to 95% of temperature A. Temperature region 3 is defined as the range of 80% to 90% of temperature A. Temperature region 4 is defined as the range of 60% to 80% of temperature A. Temperature region 5 is defined as the range of less than 60% of temperature A. Temperature A is a specified temperature, such as the temperature at which a known cooling device operates. In the target temperature distribution, the frequency proportion of temperature region 1 is less than 10%, the frequency proportion of temperature region 2 is higher than that of temperature region 1, the frequency proportion of temperature region 3 is higher than that of temperature region 2, and the frequency proportion of temperature region 4 is 40% or more. By reducing this frequency, the frequency of high-temperature regions is also reduced (so that they are distributed on the lowest possible temperature side), with the aim of preventing further degradation.

[0058] The cooling control unit 204 controls the cooling capacity of the cooling device 40 according to the cooling level LV of the cooling device 40.

[0059] Alternatively, the higher the cooling level LV, the higher the cooling capacity of the cooling device 40. For example, the higher the cooling level LV, the higher the frequency of the compressor 71. Or, when the cooling device 40 is an air-cooled cooling device, the higher the cooling level LV, the greater the cooling air volume based on the blower. Alternatively, when the cooling device 40 is a water-cooled cooling device, the higher the cooling level LV, the greater the output of the cooling mechanism.

[0060] The cooling control unit 204 can also control the cooling device 40 in a cooling mode at a determined cooling level LV to bring the battery 21 to a target temperature (e.g., below 25°C). The cooling control unit 204 can also control the cooling device 40 in a cooling mode 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), and increases the cooling capacity when the current temperature frequency distribution deviates towards a side where the temperature is higher than the target temperature frequency distribution, and decreases the cooling capacity when it deviates towards a side where the temperature is lower than the target temperature frequency distribution.

[0061] Figure 5 This is a flowchart illustrating the cooling control steps of the battery 21 of the vehicle according to the first embodiment.

[0062] In step S101, the data acquisition unit 201 acquires the road category of the vehicle at a future time from the navigation information.

[0063] In step S102, the data acquisition unit 201 acquires the temperature information of the vehicle's driving location at a future time from the navigation (net) information.

[0064] In step S103, the arrival temperature prediction unit 202 predicts the arrival temperature of the vehicle's battery 21 at a future time based on the type of road the vehicle will be traveling on at a future time and the air temperature at the location where the vehicle will be traveling at a future time. For example, the arrival temperature of the battery 21 can be predicted in N stages.

[0065] 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 in M ​​stages.

[0066] In step S105, the cooling control unit 204 controls the cooling device 40 so that the cooling capacity of the cooling device 40 is a cooling capacity corresponding to the set cooling level LV of the battery 21.

[0067] In step S106, if a specified condition is met, the process proceeds to step S107. The specified condition means that the temperature of the battery 21 becomes a target temperature (e.g., below 25°C) or the temperature frequency distribution of the battery 21 becomes a target temperature frequency distribution.

[0068] In step S107, the cooling control unit 204 stops controlling the cooling device 40 corresponding to the set cooling level LV of the battery 21.

[0069] As described above, according to this embodiment, by predicting the battery's arrival temperature based on the road type and temperature of the vehicle's driving location, and cooling the battery with a cooling level based on the predicted battery arrival temperature, the battery can be effectively cooled.

[0070] Vehicle batteries deteriorate when exposed to high temperatures; therefore, battery cell temperatures are monitored, and cooling is performed if a specified temperature is exceeded. Conversely, frequent occurrences of temperatures slightly above the specified temperature also lead to degradation. In this embodiment, to reduce the frequency of slightly higher temperature regions, the battery temperature is accurately predicted based on the driving route and ambient temperature, and cooling is adjusted in stages according to the predicted battery temperature. Thus, by keeping the battery temperature below the specified temperature or avoiding high-temperature frequency, degradation can be suppressed.

[0071] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is not shown in the foregoing description, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0072] Symbol Explanation

[0073] 8-Cooling path, 10-Drive unit, 11, 12-Motor generator, 14-Engine, 15-Power splitter, 16-Drive wheel, 20-Battery pack, 21-Battery, 22-Jack box, 23-Electric heater, 24-Current sensor, 30-Charging unit, 31-Air intake, 32-Converter, 33-Charging relay, 40-Cooling device, 41-Refrigerant circuit, 42-Cooler, 43-Coolant circuit, 50-Air conditioning duct, 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 - Liquid storage 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 - Arrival temperature prediction unit; 203 - Cooling level determination unit; 204 - Cooling control unit; 300 - Cooling system.

Claims

1. A battery cooling system, characterized in that, have: A cooling device configured to cool the vehicle's battery; and A control device that controls the cooling device. The control device includes: An arrival temperature prediction unit predicts the arrival temperature of the battery based on the road type and the ambient temperature of the driving location; a cooling level determination unit determines the cooling level of the cooling device based on the arrival temperature; and The cooling control unit controls the cooling capacity of the cooling device according to the cooling level of the cooling device.

2. The battery cooling system according to claim 1, characterized in that, The cooling control unit controls the temperature of the battery to be below a specified temperature.

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

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