A control method of a pure electric vehicle thermal management system

Abstract

The application belongs to the technical field of new energy vehicles, and relates to a control method of a pure electric vehicle thermal management system. The summer mode is used when the ambient temperature is greater than 30 DEG C, and the summer mode includes passenger cabin refrigeration, battery pack cooling and electric drive cooling. The summer mode includes three subcircuits. The first electronic water pump (13) drives the cooling liquid, the cooling liquid flows and supplies the heat of the electric energy supply system (14) and the electric drive system 15, passes through the a / b port of the first four-way valve (16), the c / b port of the first three-way valve 17, the second chiller (23), the c / d port of the second four-way valve (18), and finally exchanges heat with the ambient air driven by the radiator (10) and the cooling fan (11) to achieve the electric drive system cooling purpose. The control method of the pure electric vehicle thermal management system can adapt to different seasonal and temperature scene requirements through switching of different circulation modes, and realizes efficient energy management of the electric vehicle.

Description

A control method for a thermal management system of a pure electric vehicle Technical Field

[0001] This invention belongs to the field of new energy vehicle technology, and more specifically, relates to a control method for a thermal management system of a pure electric vehicle. Background Technology

[0002] The requirements for new energy vehicles are becoming increasingly stringent, but many problems still exist in their use. Among these, the short driving range and low efficiency of pure electric vehicles in winter and summer are particularly prominent. The thermal management system of a pure electric vehicle includes passenger compartment thermal management, electric drive system thermal management, and power battery thermal management. By formulating a thermal system plan, these three systems are controlled within a suitable temperature range to ensure the safety and comfort of people and the vehicle. Energy consumption is unavoidable in this process, and since the power battery is the only energy source, it has a significant impact on the driving range of the pure electric vehicle. Currently, traditional pure electric vehicle thermal management systems generally have high energy consumption, low efficiency, and poor thermal coupling. There is an urgent need for a method to achieve efficient energy management of all system components, thereby increasing the overall vehicle range. The shortcomings of existing technologies are: 1. In current conventional thermal management systems, the heat generated by the air conditioning system, electric drive system, and battery pack system is indirectly or indirectly discharged into the air through radiators without being utilized, resulting in a large amount of energy waste; 2. Currently, conventional air conditioning heat pump systems generally use a dual heat exchanger system. When heating at low temperatures, the outdoor heat exchanger is prone to frosting, leading to a decrease in heat exchange capacity and consequently a decrease in the efficiency of the heat pump system.

[0003] Existing technology includes a subsystem for cooling electronic power devices, a subsystem for air conditioning and heating, and a subsystem for cooling and heating the battery pack. The thermal management system for a pure electric vehicle described in this invention uses water cooling for the battery pack and couples it to the air conditioning system via a heat exchange device. The high COP value of the air conditioning system removes heat from the battery pack outside the vehicle, improving cooling efficiency and reducing energy consumption. For heating the battery pack at low temperatures, water cooling is also used, employing a water-based PTC heater. The heating and cooling of the battery pack share a single water circulation system, switched between the two by a solenoid valve, reducing flow resistance and saving space. However, this technology does not address the technical problems and solutions of this application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a control method for a pure electric vehicle thermal management system that addresses the shortcomings of the prior art. This method is simple in steps, integrates the structure of various system components and the heating and cooling requirements of the passenger compartment, and effectively adapts to the needs of different seasons and temperature scenarios by switching between different circulation modes. It does not increase additional costs, effectively achieves efficient energy management of electric vehicles, increases the driving range of the entire vehicle, and comprehensively improves the performance of electric vehicles.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] This invention relates to a control method for a thermal management system of a pure electric vehicle. The control method includes a summer mode, which is used when the ambient temperature is greater than 30°C. The summer mode includes passenger compartment cooling, battery pack cooling, and electric drive cooling. The summer mode comprises three sub-loops. The steps of the summer mode are as follows:

[0007] S1. Summer mode sub-loop one: The first electronic water pump drives the coolant. The coolant flows with the heat from the power supply system and the electric drive system. It passes through the a / b port of the first four-way valve, the c / b port of the first three-way valve, the second chiiller, and the c / d port of the second four-way valve. Finally, it exchanges heat with the ambient air driven by the radiator and the cooling fan to achieve the purpose of cooling the electric drive system.

[0008] S2. Summer Mode Sub-loop Two: The air conditioning refrigeration system loop consists of an electric compressor, a first chiller, an electronic expansion valve 22, a second chiller, and a gas-liquid separator. Condensation occurs in the first chiller, where the coolant, driven by the first electronic water pump, reacts with the first chiller. The coolant then passes through the b / d ports of the first four-way valve and finally exchanges heat with the ambient air driven by the radiator and cooling fan. Evaporation occurs in the second chiller, where the coolant, driven by the third electronic water pump, passes through the second heat exchanger and the b / c ports of the third three-way valve. This carries the hot air from the passenger compartment to the second chiller for evaporation, achieving the purpose of cooling the passenger compartment.

[0009] S3. In the summer mode sub-loop three, the fourth electronic water pump drives the coolant, which passes through the first heat exchanger and the c / b port of the first four-way valve, carrying the heat generated by the power battery to the second heat exchanger to exchange heat with the low-temperature coolant, thereby achieving the purpose of cooling the power battery.

[0010] The control method of the pure electric vehicle thermal management system also includes a spring and autumn mode, which includes passenger compartment cooling, battery pack radiator cooling, and electric drive cooling. The spring and autumn mode includes a first spring and autumn mode and a second spring and autumn mode.

[0011] Spring and Autumn First Mode:

[0012] This mode is used when the ambient temperature is between 10 and 25°C and the battery pack cooling requirement is not high. The air conditioning cooling circuit in this mode is the same as the summer mode. The difference is that the fourth three-way valve is in the A / C port open state, and the first four-way valve is in the A / B port open state and the C / D port open state, so that the electric drive system cooling circuit and the battery pack cooling circuit are connected in series. The first and fourth electronic water pumps work together to drive the coolant to carry the heat from the power supply system, electric drive system and power battery to the radiator for heat exchange, so as to achieve the purpose of cooling the electric drive and battery pack together.

[0013] The second mode described in spring and autumn:

[0014] The second mode in spring and autumn is the waste heat utilization mode of battery pack and electric drive system. In this mode, the ambient temperature is 0~10℃, and the cooling requirements of electric drive and battery pack are not high. The heat generated by electric drive system and battery maintains system thermal balance. Unlike the first mode in spring and autumn, the second four-way valve is located at the C / A port. The first and fourth electronic water pumps drive the coolant to circulate the heat of power supply system, electric drive system and power battery directly internally without passing through the radiator to achieve thermal balance.

[0015] The control method for the thermal management system of the pure electric vehicle also includes a winter mode, which includes a first winter mode, a second winter mode, a third winter mode, and a fourth winter mode.

[0016] Winter Mode 1:

[0017] The first winter mode is passenger compartment heating and battery pack heating PTC. In this mode, the ambient temperature is below -20℃, and both the passenger compartment and the battery pack require heating. When the PTC is activated, the second electronic water pump drives the coolant to be heated in the PTC. When passing through the b / c port of the second three-way valve, the heat is carried to the heating core to achieve the goal of heating the passenger compartment. When passing through the b / a port of the second three-way valve 32, the heat is carried to the first heat exchanger for heat exchange. Then, the fourth electronic water pump drives the coolant to pass through the c / b port of the first four-way valve to the power battery to achieve the purpose of heating the battery pack. The fourth three-way valve is in the a / c port open state.

[0018] The second winter mode described above:

[0019] The second winter mode involves heating the passenger compartment and using a heat pump to absorb waste heat from the electric drive system. This mode is designed for winter environments with temperatures ranging from -20°C to 0°C, where both the passenger compartment and battery pack require heating. The passenger compartment heating coolant circuit and the battery pack heating coolant circuit are identical to the first winter mode. The difference is that the PTC is off, and the heat pump provides the heat. The air conditioning heat pump system circuit consists of an electric compressor, a first chiller, an electronic expansion valve, a second chiller, and a gas-liquid separator. In the first chiller, heat is carried away by the passenger compartment heating coolant circuit, resulting in a condensation reaction. In the second chiller, an evaporation reaction occurs. The first electronic water pump drives the coolant, which carries heat from the electrical supply system and the electric drive system. The coolant travels through the a / b ports of the first four-way valve and the c / b ports of the first three-way valve to the second chiller for evaporation. The second four-way valve is in the c / a port open state.

[0020] The third winter mode described above:

[0021] The third winter mode is a heat pump that uses the passenger compartment heating system to absorb waste heat from the electric drive system and battery pack. This mode is used when the ambient temperature is -20~0℃ in winter and only the passenger compartment needs heating. The refrigerant circuit of the heat pump system and the coolant circuit of the passenger compartment heating system are the same as those in the second winter mode. The difference is that the first four-way valve is in the open state of port a / b and port c / d, so that the cooling circuit of the electric drive system and the cooling circuit of the battery pack are connected in series. The first and fourth electronic water pumps drive the coolant to carry the heat from the power supply system, electric drive system and power battery 52 to the second chiller for evaporation reaction.

[0022] The fourth winter mode described above:

[0023] The fourth winter mode involves the passenger compartment heating system using a heat pump to absorb waste heat from the electric drive system and cool the battery pack. This mode is used when the ambient temperature is -20 to 0°C in winter, requiring heating for the passenger compartment and cooling for the battery pack. The refrigerant circuit of the heat pump system and the coolant circuit of the passenger compartment heating system are the same as in the third winter mode. The difference is that the first four-way valve is in the open state at both port A / B and port C / B. The fourth electric water pump, passing through the heat exchanger and port C / B of the first four-way valve, carries the heat from the power battery to the second heat exchanger for heat exchange. The fourth three-way valve is in the open state at port B / C, and the third electric water pump drives the coolant to carry the heat to the second chiller. At the same time, the coolant absorbs heat and undergoes an evaporation reaction with the refrigerant of the heat pump system, achieving the purpose of cooling the battery pack.

[0024] In the summer mode, when the summer mode sub-loop one is in operation, the pure electric vehicle thermal management system uses the first temperature sensor to detect the loop temperature in order to control the airflow of the cooling fan and the flow rate of the electronic water pump; when the summer mode loop two is in operation, the pure electric vehicle thermal management system uses the pressure sensor and temperature and pressure sensor to detect the refrigerant status and adjust the opening of the electronic expansion valve and control the speed of the electric compressor.

[0025] In the summer mode, when the summer mode sub-loop is three, the thermal management system of the pure electric vehicle detects the coolant temperature of the loop using the second and third temperature sensors and controls the flow rate of the fourth electronic water pump.

[0026] In the second winter mode, the pure electric vehicle's thermal management system uses pressure sensors and temperature and pressure sensors to detect the refrigerant status and adjust the opening of the electronic expansion valve and control the speed of the electric compressor.

[0027] The working principle and beneficial effects of the technical solution adopted in this invention are as follows:

[0028] The control method of the pure electric vehicle thermal management system described in this invention aims to solve the technical problems existing in the prior art and provides a pure electric vehicle thermal management system with a high degree of thermal coupling. The method of using this system has the following beneficial effects: 1. By utilizing the conversion of various valve systems, multi-mode switching can be realized, so that all waste heat from the air conditioning system, electric drive system, and battery pack system can be recycled, thereby reducing energy consumption; 2. Both air conditioning cooling and heating adopt indirect heat pump systems, and the outdoor heat exchanger is eliminated, avoiding the problem of reduced efficiency due to frost on the outdoor heat exchanger and improving efficiency. Attached Figure Description

[0029] The following is a brief explanation of the contents depicted in the accompanying drawings and the markings therein:

[0030] Figure 1 is a schematic diagram of the overall principle of the thermal management system for pure electric vehicles according to the present invention;

[0031] Figure 2 is a schematic diagram of the summer mode of the thermal management system for pure electric vehicles according to the present invention;

[0032] Figure 3 is a schematic diagram of the first mode of spring and autumn of the thermal management system for pure electric vehicles according to the present invention.

[0033] Figure 4 is a schematic diagram of the second mode of spring and autumn for the thermal management system of pure electric vehicles according to the present invention;

[0034] Figure 5 is a schematic diagram of the first winter mode of the thermal management system for pure electric vehicles according to the present invention;

[0035] Figure 6 is a schematic diagram of the second winter mode of the thermal management system for pure electric vehicles according to the present invention;

[0036] Figure 7 is a schematic diagram of the third winter mode of the thermal management system for pure electric vehicles according to the present invention;

[0037] Figure 8 is a schematic diagram of the fourth winter mode of the thermal management system for pure electric vehicles according to the present invention;

[0038] The labels in the attached diagram are as follows: 10, radiator; 11, cooling fan; 12, first expansion tank; 13, first electric water pump; 14, power supply system; 15, electric drive system; 16, first four-way valve; 17, first three-way valve; 18, second four-way valve; 19, first temperature sensor; 20, electric compressor; 21, first chiller; 22, electronic expansion valve; 23, second chiller; 24, gas-liquid separator; 25, temperature and pressure sensor. ; 26. Pressure sensor; 30. Second electronic water pump; 31. PTC; 32. Second three-way valve; 33. Heating core; 34. Second expansion tank; 40. Third electronic water pump; 41. Third three-way valve; 42. Cooling core; 43. Blower; 44. Third expansion tank; 50. Fourth electronic water pump; 51. First heat exchanger; 52. Power battery; 53. Second heat exchanger; 54. Fourth three-way valve; 55. Fourth expansion tank; 56. Second temperature sensor; 57. Third temperature sensor. Detailed Implementation

[0039] The following description, with reference to the accompanying drawings, provides a more detailed explanation of the specific embodiments of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the functions and working principles of each part:

[0040] As shown in Figures 1 and 2, this invention provides a control method for a thermal management system of a pure electric vehicle. The control method includes a summer mode, which is used when the ambient temperature is greater than 30°C. The summer mode includes passenger compartment cooling, battery pack cooling, and electric drive cooling. The summer mode comprises three sub-loops. The steps of the summer mode are as follows:

[0041] S1. Summer Mode Sub-loop 1: The first electric water pump 13 drives the coolant. The coolant flows carrying heat from the electric power supply system 14 and the electric drive system 15, passing through the a / b ports of the first four-way valve 16, the c / b ports of the first three-way valve 17, the second chiller 23, and the c / d ports of the second four-way valve 18. Finally, it exchanges heat with the ambient air driven by the radiator 10 and the cooling fan 11, achieving the cooling purpose of the electric drive system. S2. Summer Mode Sub-loop 2: The electric compressor 20, the first chiller 21, the electronic expansion valve 22, the second chiller 23, and the gas-liquid separator 24 form the air conditioning refrigeration system loop. Condensation takes place in the first chiller 21. The first electric water pump 13 drives the coolant to react with the first chiller 21, and the coolant passes through the b / d ports of the first four-way valve 16. The heat exchange occurs at the port, where the radiator 10 and the ambient air driven by the cooling fan 11 exchange heat. Evaporation takes place in the second chiller 23. The third electric water pump 40 drives the coolant through the second heat exchanger 53 and the b / c ports of the third three-way valve 41, bringing the hot air from the passenger compartment to the cooling core 42 to the second chiller 23 for evaporation, thus achieving the purpose of cooling the passenger compartment. In the summer mode sub-loop three, the fourth electric water pump 50 drives the coolant through the first heat exchanger 51 and the c / b ports of the first four-way valve 16, bringing the heat generated by the power battery 52 to the second heat exchanger 53 for heat exchange with the low-temperature coolant, thus achieving the purpose of cooling the power battery. The above steps effectively meet the requirements of passenger compartment cooling, battery pack cooling, and electric drive cooling for the use environment of pure electric vehicles in summer. The control method of the pure electric vehicle thermal management system described in this invention has simple steps. By integrating the structure of each component of the system and the heating and cooling requirements of the passenger compartment, and by switching between different circulation modes, it can adapt to the needs of different seasons and temperature scenarios without increasing additional costs. It can effectively achieve efficient energy management of electric vehicles, increase the driving range of the whole vehicle, and improve the performance of electric vehicles.

[0042] The control method of the pure electric vehicle thermal management system described in this invention aims to solve the technical problems existing in the prior art and provides a pure electric vehicle thermal management system with a high degree of thermal coupling. The method of using this system has the following beneficial effects: 1. By utilizing the conversion of various valve systems, multi-mode switching can be realized, so that all waste heat from the air conditioning system, electric drive system, and battery pack system can be recycled, thereby reducing energy consumption; 2. Both air conditioning cooling and heating adopt indirect heat pump systems, and the outdoor heat exchanger is eliminated, avoiding the problem of reduced efficiency due to frost on the outdoor heat exchanger and improving efficiency.

[0043] The control method of the pure electric vehicle thermal management system also includes a spring and autumn mode, which includes passenger compartment cooling, battery pack radiator cooling, and electric drive cooling. The spring and autumn mode includes a first spring and autumn mode and a second spring and autumn mode.

[0044] As shown in Figure 3, this is the first mode for spring and autumn: this mode is used when the ambient temperature is between 10 and 25°C and the battery pack cooling requirement is not high; the air conditioning cooling circuit in this mode is the same as the summer mode. The difference is that the fourth three-way valve 54 is in the A / C port open state, and the first four-way valve 16 is in the A / B port open state and the C / D port open state, so that the electric drive system cooling circuit and the battery pack cooling circuit are connected in series. The first electronic water pump 13 and the fourth electronic water pump 50 jointly drive the coolant to carry the heat from the power supply system 14, the electric drive system 15, and the power battery 52 to the radiator 10 for heat exchange, so as to achieve the purpose of cooling the electric drive and the battery pack together.

[0045] As shown in Figure 4, this is the second mode for spring and autumn: the second mode for spring and autumn is the waste heat utilization mode of battery pack and electric drive system. In this mode, the ambient temperature is 0~10℃, and the cooling requirements of electric drive and battery pack are not high. The heat generated by electric drive system and battery maintains system thermal balance. Unlike the first mode for spring and autumn, the second four-way valve 18 is located at the c / a port. The first electronic water pump 13 and the fourth electronic water pump 50 jointly drive the coolant to circulate the heat of power supply system 14, electric drive system 15 and power battery 52 directly internally without passing through radiator 10 to achieve thermal balance.

[0046] The control method for the thermal management system of the pure electric vehicle also includes a winter mode, which includes a first winter mode, a second winter mode, a third winter mode, and a fourth winter mode.

[0047] As shown in Figure 5, this is the first winter mode: the first winter mode is for passenger compartment heating and battery pack heating PTC. In this mode, the ambient temperature is below -20℃, and both the passenger compartment and the battery pack have heating requirements. PTC31 is turned on, and the second electronic water pump 30 drives the coolant to be heated in PTC31. When passing through the b / c port of the second three-way valve 32, the heat is carried to the heating core 33 to achieve the goal of heating the passenger compartment. When passing through the b / a port of the second three-way valve 32, the heat is carried to the first heat exchanger 51 for heat exchange. The fourth electronic water pump 50 drives the coolant to pass through the c / b port of the first four-way valve 16 to the power battery 52 to achieve the purpose of heating the battery pack. The fourth three-way valve 54 is in the a / c port open state.

[0048] As shown in Figure 6, this is the second winter mode: the second winter mode involves heating the passenger compartment and using a heat pump to absorb waste heat from the electric drive system. This environment is used when the ambient temperature is -20 to 0°C in winter, and both the passenger compartment and the battery pack require heating. In this mode, the passenger compartment heating coolant circuit and the battery pack heating coolant circuit are the same as in the first winter mode; the difference is that PTC31 is turned off, and the heat is provided by the heat pump. The air conditioning heat pump system circuit consists of electric compressor 20, first chiller 21, electronic expansion valve 22, second chiller 23, and gas-liquid separator 24. In the first chiller 21, the passenger compartment heating coolant circuit carries away the heat, resulting in a condensation reaction; in the second chiller 23, an evaporation reaction occurs; the first electronic water pump 13 drives the coolant, and the coolant flow carries the heat from the electrical power supply system 14 and the electric drive system 15, passing through the a / b ports of the first four-way valve 16 and the c / b ports of the first three-way valve 17 to reach the second chiller 23 for an evaporation reaction. The second four-way valve 18 is in the c / a port open state.

[0049] As shown in Figure 7, this is the third winter mode: the third winter mode is a heat pump for heating the passenger compartment that absorbs waste heat from the electric drive system and battery pack. This mode is used when the ambient temperature is -20~0℃ in winter and only the passenger compartment needs heating. The refrigerant circuit of the heat pump system and the coolant circuit for heating the passenger compartment are the same as those in the second winter mode. The difference is that the first four-way valve 16 is in the open state of port a / b and port c / d, so that the cooling circuit of the electric drive system and the cooling circuit of the battery pack are connected in series. The first electronic water pump 13 and the fourth electronic water pump 50 jointly drive the coolant to carry the heat from the power supply system 14, the electric drive system 15 and the power battery 52 to the second chiller 23 for evaporation reaction.

[0050] As shown in Figure 8, this is the fourth winter mode: the fourth winter mode is used for passenger compartment heating, where the heat pump absorbs waste heat from the electric drive system and cools the battery pack. This mode is used when the ambient temperature is -20~0℃ in winter, the passenger compartment has a heating requirement, and the battery pack has a cooling requirement. The refrigerant circuit of the heat pump system and the cooling fluid circuit of the passenger compartment heating are the same as those in the third winter mode. The difference is that the first four-way valve 16 is in the a / b port open state and the c / b port open state. The fourth electronic water pump 50, through the heat exchanger 51 and the c / b port of the first four-way valve 16, carries the heat from the power battery 52 to the second heat exchanger 53 for heat exchange. The fourth three-way valve 54 is in the b / c port open state, and the third electronic water pump 40 drives the coolant to carry the heat to the second chiller 23. At the same time, it absorbs heat and undergoes an evaporation reaction with the refrigerant of the heat pump system to achieve the purpose of cooling the battery pack.

[0051] In the summer mode, when the summer mode sub-loop is one, the pure electric vehicle thermal management system uses the first temperature sensor 19 to detect the loop temperature in order to control the airflow of the cooling fan 11 and the flow rate of the first electronic water pump 13; when the summer mode loop is two, the pure electric vehicle thermal management system uses the pressure sensor 25 and the temperature and pressure sensor 26 to detect the refrigerant status, and adjusts the opening of the electronic expansion valve 22 and controls the speed of the electric compressor 20.

[0052] In the summer mode, when the summer mode sub-loop is three, the thermal management system of the pure electric vehicle detects the coolant temperature of the loop using the second temperature sensor 56 and the third temperature sensor 57, and controls the flow rate of the fourth electronic water pump 50.

[0053] In the second winter mode, the pure electric vehicle thermal management system uses pressure sensor 25 and temperature and pressure sensor 26 to detect the refrigerant status, adjust the opening of electronic expansion valve 22 and control the speed of electric compressor 20. Unlike traditional heat pumps, which are prone to frost formation on the outdoor heat exchanger when heating at low temperatures, resulting in a decrease in heat exchange capacity, this system mode avoids this problem.

[0054] The control method of the pure electric vehicle thermal management system described in this invention aims to solve the technical problems existing in the prior art and provides a pure electric vehicle thermal management system with a high degree of thermal coupling. The method of using this system has the following beneficial effects: 1. By utilizing the conversion of various valve systems, multi-mode switching can be realized, so that all waste heat from the air conditioning system, electric drive system, and battery pack system can be recycled, thereby reducing energy consumption; 2. Both air conditioning cooling and heating adopt indirect heat pump systems, and the outdoor heat exchanger is eliminated, avoiding the problem of reduced efficiency due to frost on the outdoor heat exchanger and improving efficiency.

[0055] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A control method for a thermal management system of a pure electric vehicle, characterized in that: The control method of the pure electric vehicle thermal management system includes a summer mode. The summer mode is used when the ambient temperature is greater than 30°C. The summer mode includes passenger compartment cooling, battery pack cooling, and electric drive cooling. The summer mode includes three sub-loops. The steps of the summer mode are as follows: S1. Sub-loop one of the summer mode: The first electronic water pump (13) drives the coolant. The coolant flows with the heat from the power supply system (14) and the electric drive system (15), passing through the a / b port of the first four-way valve (16), the c / b port of the first three-way valve (17), the second chiller (23), and the second four-way valve (18). The C / D ports of the radiator (10) and the ambient air driven by the cooling fan (11) exchange heat to achieve the purpose of cooling the electric drive system; S2. Summer mode sub-loop two: The electric compressor (20), the first chiller (21), the electronic expansion valve (22), the second chiller (23), and the gas-liquid separator (24) form the air conditioning refrigeration system loop. The condensation takes place in the first chiller (21). The coolant is driven by the first electronic water pump (13) to react with the first chiller (21) to condense. The coolant passes through the B / D ports of the first four-way valve (16). The port is ultimately used for heat exchange between the radiator (10) and the ambient air driven by the cooling fan (11); evaporation takes place in the second chiller (23), and the third electronic water pump (40) drives the coolant through the second heat exchanger (53) and the b / c port of the third three-way valve (41) to bring the hot air brought from the passenger compartment by the cooling core (42) to the second chiller (23) for evaporation reaction, so as to achieve the purpose of cooling the passenger compartment; S3. Summer mode sub-loop three, the fourth electronic water pump (50) drives the coolant through the first heat exchanger (51) and the c / b port of the first four-way valve (16) to bring the heat generated by the power battery (52) to the second heat exchanger (53) for heat exchange with the low temperature coolant, so as to achieve the purpose of cooling the power battery; The control method of the pure electric vehicle thermal management system also includes a winter mode, which includes a winter first mode, a winter second mode, a winter third mode, and a winter fourth mode: winter first mode: winter first mode is passenger compartment heating and battery pack heating PTC, and the ambient temperature in this mode is below -20℃; When the PTC (31) is turned on, the second electronic water pump (30) drives the coolant to be heated in the PTC (31). When passing through the b / c port of the second three-way valve (32), the heat is carried to the heating core (33) to achieve the goal of heating the passenger compartment. When passing through the b / a port of the second three-way valve (32), the heat is carried to the first heat exchanger (51) for heat exchange. The fourth electronic water pump (50) drives the coolant to be carried through the c / b port of the first four-way valve (16) to the power battery (52) to achieve the purpose of heating the battery pack. The fourth three-way valve (54) is in the a / c port open state. The winter second mode: the winter second mode is passenger compartment heating and electric The battery pack heating heat pump absorbs waste heat from the electric drive. This environment is used in winter when the ambient temperature is -20~0℃, and both the passenger compartment and the battery pack have heating requirements. In this mode, the passenger compartment heating coolant circuit and the battery pack heating coolant circuit are the same as in the first winter mode. The difference is that the PTC (31) is turned off, and the heat is provided by the heat pump. The air conditioning heat pump system circuit consists of an electric compressor (20), a first chiller (21), an electronic expansion valve (22), a second chiller (23), and a gas-liquid separator (24). In the first chiller (21), the heat is carried away by the passenger compartment heating coolant circuit, and a condensation reaction occurs. In the second chiller (23)... An evaporation reaction occurs; the coolant is driven by the first electronic water pump (13), and the coolant flows carrying the heat from the power supply system (14) and the electric drive system (15), passing through the a / b port of the first four-way valve (16) and the c / b port of the first three-way valve (17) to the second chiller (23) for an evaporation reaction, and the second four-way valve (18) is in the c / a port open state; the third winter mode: the third winter mode is that the crew cabin heating heat pump absorbs the waste heat of the electric drive system and battery pack. This mode is used for winter ambient temperatures of -20~0℃, and this mode only requires crew cabin heating; the refrigerant circuit of the heat pump system and the coolant circuit of the crew cabin heating are both connected to the third winter mode. The two modes are the same, except that the first four-way valve (16) is in the a / b port open state and the c / d port open state, so that the cooling circuit of the electric drive system and the cooling circuit of the battery pack are connected in series. The first electronic water pump (13) and the fourth electronic water pump (50) jointly drive the coolant to carry the heat of the power supply system (14), the electric drive system (15) and the power battery (52) to the second chiller (23) for evaporation reaction; the fourth winter mode: the fourth winter mode is that the crew cabin heating heat pump absorbs the waste heat of the electric drive system and the battery pack is cooled; this mode is used when the winter ambient temperature is -20~0℃. In this mode, the crew cabin has a heating requirement and the battery pack has a cooling requirement;The refrigerant circuit of the heat pump system and the cooling fluid circuit for the passenger compartment are the same as in the third winter mode. The difference is that the first four-way valve (16) is in the open state of both port a / b and port c / b. The fourth electronic water pump (50) passes through the heat exchanger (51) and the c / b port of the first four-way valve (16) to carry the heat from the power battery (52) to the second heat exchanger (53) for heat exchange. The fourth three-way valve (54) is in the open state of port b / c. The third electronic water pump (40) drives the coolant to carry the heat to the second chiller (23), and at the same time, it absorbs heat and evaporates with the refrigerant of the heat pump system to achieve the purpose of cooling the battery pack.

2. The control method for the thermal management system of a pure electric vehicle according to claim 1, characterized in that: The control method of the pure electric vehicle thermal management system also includes a spring and autumn mode. The spring and autumn mode includes passenger compartment cooling, battery pack radiator cooling, and electric drive cooling. The spring and autumn mode includes spring and autumn first mode and spring and autumn second mode. Spring and autumn first mode: This mode is used when the ambient temperature is 10~25℃. The air conditioning cooling circuit in this mode is the same as the summer mode. The difference is that the fourth three-way valve (54) is in the a / c port open state, and the first four-way valve (16) is in the a / b port open state and the c / d port open state, so that the electric drive system cooling circuit and the battery pack cooling circuit are connected in series. The first electronic water pump (13) and the fourth electronic water pump (50) jointly drive the coolant to carry the heat of the power supply system (14), electric drive system (15), and power battery (52) to the radiator (10) for heat exchange, so as to achieve the purpose of cooling the electric drive and battery pack together.

3. The control method for the thermal management system of a pure electric vehicle according to claim 2, characterized in that: The second mode in spring and autumn: The second mode in spring and autumn is the waste heat utilization mode of battery pack and electric drive system. The ambient temperature in this mode is 0~10℃. The electric drive system and battery generate heat to maintain the thermal balance of the system. Unlike the first mode in spring and autumn, the second four-way valve (18) is located at the c / a port. The first electronic water pump (13) and the fourth electronic water pump (50) jointly drive the coolant to directly circulate the heat of the power supply system (14), electric drive system (15) and power battery (52) without passing through the radiator (10) to achieve the purpose of thermal balance.

4. The control method for the thermal management system of a pure electric vehicle according to claim 1, characterized in that: In the summer mode, when the summer mode sub-loop is one, the pure electric vehicle thermal management system uses the first temperature sensor (19) to detect the loop temperature in order to control the air volume of the cooling fan (11) and the flow rate of the first electronic water pump (13); when the summer mode loop is two, the pure electric vehicle thermal management system uses the pressure sensor (25) and the temperature and pressure sensor (26) to detect the refrigerant status, and adjusts the opening of the electronic expansion valve (22) and controls the speed of the electric compressor (20).

5. The control method for the thermal management system of a pure electric vehicle according to claim 4, characterized in that: In the summer mode, when the summer mode sub-loop is three, the thermal management system of the pure electric vehicle detects the coolant temperature of the loop by the second temperature sensor (56) and the third temperature sensor (57) and controls the flow rate of the fourth electronic water pump (50).

6. The control method for the thermal management system of a pure electric vehicle according to claim 1 or 2, characterized in that: In the second winter mode, the thermal management system of the pure electric vehicle detects the refrigerant status by combining the pressure sensor (25) and the temperature and pressure sensor (26), and adjusts the opening of the electronic expansion valve (22) and controls the speed of the electric compressor (20).

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