Thermal management system and method for pure electric vehicle

Abstract

The invention belongs to the field of new energy vehicles, and discloses a thermal management system and method for a pure electric vehicle, which integrates a heat pump air conditioning system, a power battery loop and a motor electric control loop. The heat pump air conditioning system can switch a refrigerating mode or a heating mode according to requirements, temperature adjustment is carried out on the passenger compartment and the power battery through different flow paths, meanwhile, waste heat recycled by the motor electric control loop can be further used for heating the passenger compartment and the power battery, and dependence on PTC is reduced. In the refrigeration mode, a refrigerant sequentially flows through the compressor, the four-way valve, the outside-vehicle heat exchanger, the expansion assembly and the inside-vehicle heat exchange assembly to achieve refrigeration. And in the heating mode, the flow direction of the refrigerant is reversed, the in-vehicle heat exchange assembly serves as a condenser to release heat, and heating is achieved. By integrating heat pump air conditioning and motor waste heat recovery, heat in the system is fully utilized, heating energy consumption is reduced, and battery power loss is reduced, so that the cruising ability of the electric vehicle in a low-temperature environment is effectively improved, and the thermal management efficiency of the whole vehicle is optimized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new energy vehicles, specifically to the field of electric vehicle thermal management, and relates to a pure electric vehicle thermal management system and method. BACKGROUND

[0002] The pure electric vehicle faces the problem of significant reduction of the cruising range in winter, and the main reasons include battery capacity attenuation under low temperature environment and high heating energy consumption. The traditional electric vehicle mainly relies on the resistance heater (PTC) to provide heat for the passenger cabin and the power battery, but its heating efficiency is low, and the energy efficiency ratio (COP) is only 1, resulting in a large amount of electric energy being consumed. Although the application of the heat pump air conditioning technology can improve the heating efficiency, the existing thermal management system still has the problem of insufficient heat utilization rate, and the waste heat resources of the motor, the electric control and other components are not fully integrated.

[0003] The current thermal management system of most pure electric vehicles adopts an independent design mode, and the passenger cabin thermal management, the power battery thermal management and the motor thermal management are separated from each other, lacking collaborative optimization. This decentralized management leads to high system heat loss, and the waste heat generated by the motor and the electric control system cannot be effectively recovered, still needing to rely on the PTC for supplementary heating, further aggravating the electric energy consumption. In addition, the contradiction between the battery performance decline under low temperature environment and the increased heating demand has not been effectively solved, which seriously restricts the cruising performance of the electric vehicle in cold climates.

[0004] Therefore, there is currently a lack of an efficient thermal management system integrating waste heat recovery and heat pump air conditioning, which leads to the inability to reduce the winter heating energy consumption and improve the cruising ability of the pure electric vehicle. SUMMARY

[0005] The application provides a pure electric vehicle thermal management system and method, and the system recovers the excess heat of the motor and the electric control system on the basis of the traditional heat pump air conditioning system, can directly heat the passenger cabin and heat and insulate the power battery, and reduces the use of the PTC as much as possible, so as to reduce the winter heating energy consumption of the pure electric vehicle and improve the winter cruising range of the pure electric vehicle.

[0006] In order to achieve the above purpose, the application adopts the following technical content: A pure electric vehicle thermal management system, comprising: a heat pump air conditioning system, a power battery loop and a motor and electric control loop integrated into one body; The heat pump air conditioning system is connected with the power battery loop, and the power battery loop is connected with the motor and electric control loop; The heat pump air conditioning system can be selectively switched to a cooling mode and a heating mode to cool or heat the passenger cabin and the power battery; The motor electric control loop can recover waste heat to heat the passenger cabin and the power battery. The heat pump air conditioning system comprises a compressor, a first four-way valve, an outside heat exchanger, an expansion assembly, an inside heat exchanger assembly; When the compressor output port, the first passage of the first four-way valve, the outside heat exchanger, the expansion assembly, the inside heat exchanger assembly, the second passage of the first four-way valve and the compressor input port form a passage, the heat pump air conditioning system switches to a refrigeration mode to refrigerate the passenger cabin and the power battery. When the compressor output port, the third passage of the first four-way valve, the inside heat exchanger assembly, the expansion assembly, the outside heat exchanger, the fourth passage of the first four-way valve and the compressor input port form a passage, the heat pump air conditioning system switches to a heating mode to heat the passenger cabin and the power battery.

[0007] Further, the expansion assembly comprises a first electronic expansion valve and a second electronic expansion valve; the inside heat exchanger assembly comprises an inside heat exchanger and a plate heat exchanger; the first electronic expansion valve is connected between the outside heat exchanger and the inside heat exchanger, and the second electronic expansion valve is connected between the outside heat exchanger and the plate heat exchanger; the plate heat exchanger is connected to the power battery, and the working medium flow path of the inside heat exchanger is arranged in the passenger cabin, and cold air is blown into the passenger cabin by a blower.

[0008] Further, the first four-way valve comprises a, b, c and d four interfaces; wherein b and d form a first passage; c and a form a second passage; b and c form a third passage; d and a form a fourth passage.

[0009] Further, the compressor output port is connected with a gas-liquid separator.

[0010] Further, the power battery circuit and the motor electric control circuit are connected through a second four-way valve; When the first passage and the second passage of the second four-way valve are connected between the power battery circuit and the motor electric control circuit, the power battery circuit and the motor electric control circuit form a series passage, and the motor electric control circuit can heat the passenger cabin and the power battery. When the third passage of the second four-way valve is communicated with the power battery circuit, and the fourth passage is communicated with the motor electric control circuit, the power battery circuit and the motor electric control circuit work independently.

[0011] Further, the second four-way valve comprises a, b, c and d four interfaces; wherein c and b form a first passage; a and d form a second passage; a and b form a third passage; c and d form a fourth passage.

[0012] Further, the power battery circuit comprises a power battery and a first water pump; a part of the in-vehicle heat exchange assembly is connected between the power battery and the first water pump; the power battery circuit is further provided with a first PTC; and the power battery circuit is connected with the motor electric control circuit through a second four-way valve.

[0013] Further, the motor electric control circuit comprises a motor electric control system, a second water pump and a radiator; the motor electric control circuit is connected with the power battery circuit through a second four-way valve; The motor electric control system is connected with the second water pump, and the motor electric control system is connected with the radiator through a second three-way valve; The radiator is further connected with a second PTC and a heater water tank in sequence; The radiator is connected with the second PTC through a third three-way valve; The motor waste heat of the motor electric control system is used to heat the passenger cabin through the radiator and the heater water tank.

[0014] A whole vehicle thermal management method for a pure electric vehicle, based on the above-mentioned pure electric vehicle thermal management system, comprising: Performing thermal management system initialization, setting initial parameters and states; Obtaining sensor data; Determining whether the passenger cabin temperature is lower than a set threshold value according to the initial parameters and states and the sensor data, and starting the heating system if it is lower; If the heating system is started, first, according to the current working condition, the heating mode is selected to be heat pump heating or heat pump and PTC common heating; according to the state and demand of the system, the flow rate of the refrigerant is controlled, and the control variable that needs to be adjusted is determined; Establishing an MPC prediction model to predict the system behavior in a future preset time through the MPC prediction model; Establishing an optimization problem according to the MPC prediction model to determine a cost function between a minimum control target and a constraint condition; Solving the optimization problem of the MPC prediction model to obtain an optimal control sequence, the optimal control sequence comprising the system behavior in the future preset time; Feeding back the optimal control sequence to the actual thermal management system, and specifically performing the following process: Adjusting the flow rate and pressure of the refrigerant in the system by adjusting the speed of the compressor; Controlling the opening and closing of the waste heat recovery function by adjusting the switch of the waste heat mode; Controlling the speed of the compressor, the power of the PTC and the waste heat recovery mode.

[0015] Further, wherein: The MPC prediction model is:

[0016] wherein, k represents the current time, k+1 represents the next time; x(k) is the passenger cabin temperature at the current time; u(k) is the control variable at the current time, including the compressor speed, PTC power and waste heat recovery mode; A and B are state matrix and control matrix; The cost function is:

[0017] wherein, N is the prediction time domain length; T cabin (k) is the passenger cabin temperature at time k; T ref is the target temperature of the passenger cabin; u(k) is the control input at k; and α, β are the corresponding weight coefficients.

[0018] Compared with the prior art, the present application has the following beneficial effects: The present application provides a pure electric vehicle thermal management system, which integrates a heat pump air conditioning system, a power battery circuit and a motor electric control circuit to realize collaborative optimization management. The heat pump air conditioning system can switch between cooling and heating modes according to requirements, and adjust the temperature of the passenger cabin and the power battery through different flow paths, respectively. Meanwhile, the waste heat recovered by the motor electric control circuit can be further used to heat the passenger cabin and the power battery, reducing the dependence on PTC. In the cooling mode, the refrigerant flows through the compressor, the four-way valve, the outdoor heat exchanger, the expansion assembly and the indoor heat exchanger assembly in turn to realize cooling. In the heating mode, the flow direction of the refrigerant is reversed, and the indoor heat exchanger assembly releases heat as a condenser to realize efficient heating. The present system integrates the heat pump air conditioner and the motor waste heat recovery, fully utilizes the internal heat of the system, reduces the heating energy consumption and the battery power loss, thereby effectively improving the endurance of the electric vehicle in low temperature environment, and optimizing the overall vehicle thermal management efficiency.

[0019] Preferably, in the present application, the fine control of the refrigerant flow path is realized by setting a double electronic expansion valve and a double heat exchanger structure. The indoor heat exchanger and the plate heat exchanger serve the passenger cabin and the power battery respectively, and can independently adjust the temperature requirements of each other, improving the flexibility and accuracy of the thermal management system, optimizing the refrigerant distribution efficiency and reducing energy loss.

[0020] Preferably, in the present application, a gas-liquid separator is additionally arranged at the output port of the compressor, which effectively prevents the liquid refrigerant from entering the compressor to cause liquid strike risk and prolongs the service life of the compressor. Meanwhile, the gas-liquid separator can optimize the refrigerant circulation quality, improve the system operation efficiency and stability.

[0021] Preferably, in the present application, the flexible connection between the power battery circuit and the motor electric control circuit is realized by the second four-way valve, and the series or independent working mode can be selected according to the requirements. In the series mode, the motor waste heat can be directly used for heating the power battery and the passenger cabin, reducing the additional energy consumption; in the independent mode, each circuit can be operated independently to meet the requirements of different working conditions, improving the adaptability of the system.

[0022] Preferably, in the present application, the efficient temperature management of the power battery is realized through the structural optimization of the power battery circuit. The first water pump ensures stable circulation of the cooling liquid, and the first electric heater serves as an auxiliary heat source to provide supplementary heating in extreme working conditions. At the same time, through the linkage of the second four-way valve and the motor electric control circuit, the waste heat resources are fully utilized, and the overall energy consumption is reduced.

[0023] Preferably, in the present application, the efficient recovery and utilization of the motor waste heat are realized through the optimized design of the motor electric control circuit. The radiator and the heater core transfer the motor waste heat to the passenger cabin, reducing the dependence on the electric heater; the use of the second electric heater and the three-way valve further enhances the flexibility and adaptability of the system, ensuring stable heating in different working conditions.

[0024] The present application also provides a pure electric vehicle thermal management method based on the above pure electric vehicle thermal management system. By combining the model predictive control (MPC) algorithm, the heat pump air conditioning system and the waste heat recovery technology, intelligent thermal management control is realized. First, the sensor data is collected and the passenger cabin temperature demand is judged, and the heat pump heating or the heat pump and PTC cooperative heating mode is dynamically selected; then the MPC prediction model is established, the control variables are predicted and optimized based on the system state and future working conditions, and the optimal control sequence is solved to adjust the compressor speed, PTC power and waste heat recovery mode, so as to accurately control the refrigerant flow, pressure and heat distribution. This method uses the multivariable optimization capability of MPC, comprehensively considers the dynamic characteristics and energy consumption constraints of the system, and adjusts the heating strategy in real time to ensure the comfort of the passenger cabin and the optimal temperature of the battery while minimizing the use of PTC and improving the utilization rate of waste heat. The use of this method effectively reduces the heating energy consumption, improves the energy utilization efficiency of the whole vehicle, significantly enhances the endurance performance of the electric vehicle in low temperature environment, and realizes the intelligentization and adaptive optimization of the thermal management system. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A structure schematic diagram of a pure electric vehicle thermal management system provided by an embodiment of the present application is shown in the figure. Figure 2 A heat pump air conditioning refrigeration mode schematic diagram of a battery provided by an embodiment of the present application is shown in the figure. Figure 3 A heat pump air conditioning heating mode schematic diagram of a battery provided by an embodiment of the present application is shown in the figure. Figure 4A schematic diagram of a waste heat recovery heating mode of the battery provided by the embodiment of the present application is shown in the figure; Figure 5 A schematic diagram of a PTC heating mode of the battery provided by the embodiment of the present application is shown in the figure; Figure 6 A schematic diagram of a heat pump air conditioning refrigeration mode of the passenger cabin provided by the embodiment of the present application is shown in the figure; Figure 7 A schematic diagram of a heat pump air conditioning heating mode of the passenger cabin provided by the embodiment of the present application is shown in the figure; Figure 8 A schematic diagram of a waste heat recovery heating mode of the passenger cabin provided by the embodiment of the present application is shown in the figure; Figure 9 A schematic diagram of a PTC heating mode of the passenger cabin provided by the embodiment of the present application is shown in the figure; Figure 10 A flow chart of the thermal management method provided by the embodiment of the present application is shown in the figure.

[0026] Reference signs: 1, compressor; 2, vehicle exterior heat exchanger; 3, first electronic expansion valve; 4, vehicle interior heat exchanger; 5, first three-way valve; 6, first four-way valve; 7, second electronic expansion valve; 8, second four-way valve; 9, plate heat exchanger; 10, first water pump; 11, second water pump; 12, second three-way valve; 13, power battery; 14, first PTC; 15, motor electric control system; 16, heater water tank; 17, second PTC; 18, radiator; 19, air blower; 20, gas-liquid separator; 21, third three-way valve. DETAILED DESCRIPTION

[0027] In order to make the technical problems solved by the present application, the technical solutions and advantages clearer, the following specific embodiments are used to further describe the present application. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

[0031] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0032] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0033] In the description of the embodiments of the present application, it should also be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] Now the technical terms involved in the present application will be explained as follows: MPC: Full name Model Predictive Control, which is an advanced control strategy based on dynamic model, rolling optimization and feedback correction, widely used in industrial automation, robots, energy management, transportation systems and other fields.

[0035] As mentioned in the background, the current air conditioning system and battery thermal management system play a crucial role in vehicle driving, so that the passenger cabin temperature and battery temperature are within the optimal temperature range, which not only affects the comfort of the passenger cabin, but also affects the service life of the power battery. However, most of the current pure electric vehicles use independent setting and separate management, which fails to achieve integrated thermal management of passenger cabin thermal management, power battery thermal management and motor thermal management. This separate management method results in high heat consumption and seriously affects the cruising range of the vehicle.

[0036] To solve the above problems, the embodiment provides a pure electric vehicle thermal management system, which recovers the excessive heat of a motor electronic control system on the basis of a traditional heat pump air conditioning system, can directly heat a passenger cabin and heat and insulate a power battery, reduces the use of PTC as much as possible, and achieves the purposes of reducing the heating energy consumption of the pure electric vehicle in winter and improving the cruising range of the pure electric vehicle in winter.

[0037] As shown in the example, Figure 1 The embodiment provides a pure electric vehicle thermal management system, which comprises a heat pump air conditioning system, a power battery loop and a motor electronic control loop, and the specific structure is as follows: The heat pump air conditioning system is composed of a compressor, a first four-way valve 6, a first electronic expansion valve 3, a second electronic expansion valve 7, an outside heat exchanger 2, an inside heat exchanger 4, a plate heat exchanger 9 and a first three-way valve 5. The first four-way valve 6 has four interfaces a, b, c and d, the b interface is connected with the compressor 1, and the d interface is connected with the outside heat exchanger 2. The first four-way valve 6 can realize the switching of the heat pump air conditioning cooling and heating modes by connecting different interfaces.

[0038] When the bd interface and the ac interface of the first four-way valve 6 are connected, the heat pump air conditioning starts the cooling mode. The compressor 1 compresses the refrigerant into a high-pressure gas, the high-temperature and high-pressure gas enters the outside heat exchanger 2 to condense and release heat, the liquid refrigerant is reduced in pressure through the first electronic expansion valve 3 and becomes a low-temperature and low-pressure liquid, and then enters the inside heat exchanger 4 (evaporator) to evaporate and absorb heat. The cold air is blown into the passenger cabin by the air blower 19. When the second electronic expansion valve 7 is opened, the low-temperature and low-pressure refrigerant enters the plate heat exchanger 9 to exchange heat with the cooling liquid of the power battery 13.

[0039] When the bc and ad interfaces of the first four-way valve 6 are connected, the heat pump air conditioning enters the heating mode. At this time, the compressor 1 compresses the refrigerant into a high-temperature and high-pressure gas, the high-temperature and high-pressure gas enters the inside heat exchanger 4, exchanges heat with the air blown by the air blower 19, and blows hot air into the passenger cabin. The gas from the inside heat exchanger 4 enters the first electronic expansion valve 3, the outside heat exchanger 2, the first four-way valve 6 and the gas-liquid separator 20, and reenters the compressor 1.

[0040] The power battery loop is composed of a first water pump 10, a power battery 13, a second four-way valve 8, a plate heat exchanger 9 and a first PTC 14.

[0041] When the temperature of the power battery 13 is too high, the heat pump air conditioner starts to cool the power battery 13. The second electronic expansion valve 7 connected with the plate heat exchanger 9 is opened, and the low-temperature and low-pressure refrigerant liquid medium is depressurized through the second electronic expansion valve 7, and then exchanges heat with the cooling liquid in the power battery 13 cooling circuit in the plate heat exchanger 9, and then returns to the refrigerant circulation loop to continue working. The cooling liquid in the power battery circuit is cooled and then radiates heat to the power battery 13 under the action of the first water pump 10, thereby realizing the refrigeration function of the heat pump air conditioner on the power battery 13.

[0042] When the temperature of the power battery 13 is too high, the heat pump air conditioner starts to cool the power battery 13. The second electronic expansion valve 7 connected with the plate heat exchanger 9 is opened, and the low-temperature and low-pressure refrigerant liquid medium is depressurized through the second electronic expansion valve 7, and then exchanges heat with the cooling liquid in the power battery 13 cooling circuit in the plate heat exchanger 9, and then returns to the refrigerant circulation loop to continue working. The cooling liquid in the power battery circuit is cooled and then radiates heat to the power battery 13 under the action of the first water pump 10, thereby realizing the refrigeration function of the heat pump air conditioner on the power battery 13. Figure 3

[0043] If the ambient temperature is too low, the heat pump air conditioner has poor heating effect, and the first PTC 14 in the power battery circuit will heat the power battery. At this time, the ab and cd interfaces of the second four-way valve 8 are connected, and the power battery 13 and the motor control circuit work independently.

[0044] The motor control circuit is composed of the second water pump 11, the second three-way valve 12, the motor control system 15, the third three-way valve 21, the warm air water tank 16, the radiator 18, the second PTC 17, and the second four-way valve 8. When the motor needs to be cooled, the ab interface of the second three-way valve 12 is connected, the ac interface of the third three-way valve 21 is connected, and the ab and cd interfaces of the second four-way valve 8 are connected. The second water pump 11 drives the high-temperature cooling liquid in the circuit to enter the radiator 18 to dissipate heat. When the passenger compartment needs to be heated and the motor control system 15 has sufficient waste heat, the ac interface of the second three-way valve 12 is connected, the bc interface of the third three-way valve 21 is connected, and the ab and cd interfaces of the second four-way valve 8 are connected. The waste heat of the motor control system 15 is transported to the warm air water tank 16 by the second water pump 11, exchanges heat with the air blown by the air blower 19, and finally enters the passenger compartment to realize heating. If the bc and ad interfaces of the second four-way valve 8 are connected, the power battery 13 and the motor control circuit will be connected in series, and the waste heat of the motor control system 15 can also heat the power battery 13.

[0045] This heat management system has three heat sources: PTC, environment, and motor waste heat. The present application has different control modes for the passenger compartment and the power battery, and different modes are converted through the opening and closing control of the four-way valves and three-way valves. The heat pump system can switch different heat management modes by adjusting the opening and closing of the electromagnetic valves according to the heat management requirements of the vehicle cabin and the power battery.​

[0046] The present invention sets different power battery thermal management operating modes based on the power battery temperature.

[0047] like Figure 2 As shown, in the cooling mode of the heat pump air conditioning system: when the power battery 13 is in a fast charging or high temperature condition, the refrigerant circuit starts to operate, exchanging heat with the power battery 13 through the plate heat exchanger 9. Among them, the bd interface of the first four-way valve 6 is connected, the ac interface is connected, the bc interface of the first three-way valve 5 is connected, and the a interface is disconnected. The high-temperature and high-pressure refrigerant flows out of the outlet of the compressor 1 and enters the off-board heat exchanger 2, the second electronic expansion valve 7, and the plate heat exchanger 9 in sequence. The low-temperature and low-pressure refrigerant exchanges heat with the coolant in the power battery 13 in the plate heat exchanger 9. It then flows through the first three-way valve 5, the first four-way valve 6, and the gas-liquid separator 20 and returns to the compressor.

[0048] like Figure 3 As shown, in the heating mode of the heat pump air conditioning system, when the power battery 13 is at a low temperature and the coolant temperature in the motor electronic control circuit is low, resulting in insufficient waste heat, the heat pump air conditioning system is used to heat the power battery 13. At this time, the bc and ad interfaces of the first four-way valve 6 are connected, and the bc interface of the first three-way valve 5 is connected. The compressor 1 compresses the refrigerant into a high-temperature, high-pressure gas, which then passes through the first four-way valve 6 and the first three-way valve 5 and enters the plate heat exchanger 9. Heat is then exchanged between the plate heat exchanger 9 and the power battery circuit. From the plate heat exchanger 9, the gas enters the second electronic expansion valve 7, the external heat exchanger 2, the first four-way valve 6, and the gas-liquid separator 20, before re-entering the compressor 1.

[0049] like Figure 4 As shown, in waste heat recovery heating mode, when the power battery 13 is at a low temperature and the motor electronic control circuit coolant temperature is high, the heat from the motor electronic control system 15 is used to heat the power battery 13. The second three-way valve 12bc is connected, the third three-way valve 21ac is connected, and the second four-way valve 8bc and ad are connected. Powered by the second water pump 11, the heat from the motor electronic control system 15 is used to heat the coolant in the power battery circuit, thereby raising the temperature of the power battery 13.

[0050] like Figure 5As shown, in PTC heating mode, when the power battery 13 requires a high amount of heating but the motor's electronic control circuit's waste heat is insufficient, if the ambient temperature is below -15°C and the heat pump air conditioner's heating efficiency is low, PTC heating will be used. During winter vehicle startup, when the motor's electronic control circuit coolant temperature is low and doesn't meet waste heat recovery requirements, and when the indoor temperature differs significantly from the set temperature, PTC heating is selected for rapid heating until the motor's electronic control circuit's waste heat meets the heating requirement. PTC heating mode is a common winter heating method for pure electric vehicles. While this method provides fast and effective heating, it also consumes significant energy due to energy loss and dissipation during the energy conversion process. Especially in winter, when the power battery's activity is low, the reduction in pure electric vehicle range caused by PTC heating is significant. When PTC mode is enabled, the four-way valve ab and cd interfaces are connected, power is provided by the first water pump 10, and the PTC heating system heats the coolant in the circuit to raise the temperature of the power battery.

[0051] The present invention sets different passenger compartment thermal management operating modes based on the passenger compartment temperature.

[0052] like Figure 6 As shown, in the heat pump air conditioning cooling mode: when the temperature in the passenger compartment is high, the high-temperature and high-pressure gaseous working medium enters the external heat exchanger 2 from the compressor 1 through the first four-way valve 6. At this time, the external heat exchanger 2 acts as a condenser to condense the working medium into liquid. The liquid refrigerant passes through the first electronic expansion valve 3 and enters the internal heat exchanger 4 to evaporate and absorb heat. The blower 19 blows the cold air into the passenger compartment, and the gaseous working medium re-enters the compressor 1 to achieve the cooling effect of the passenger compartment.

[0053] like Figure 7 As shown, in heating mode, the heat pump air conditioner heats the passenger compartment when the passenger compartment temperature is low and the motor circuit's residual heat is insufficient. When the vehicle is started in winter, the motor circuit coolant temperature is low. When the ambient temperature is above -15°C, the heat pump air conditioner's heating energy efficiency ratio is higher than that of the PTC. When the heat pump air conditioner is in heating mode, the bc and ad ports of the first four-way valve 6 are connected, and the bc port of the first three-way valve 5 is connected. Compressor 1 compresses the refrigerant into high-temperature, high-pressure gas, which then passes through the first four-way valve 6 and the first three-way valve 5 and enters the interior heat exchanger 4. There, it exchanges heat with the air from the blower 19, and the hot air is blown into the passenger compartment. The gas exiting the interior heat exchanger 4 enters the first electronic expansion valve 3, the exterior heat exchanger 2, the first four-way valve 6, and the gas-liquid separator 20, before re-entering compressor 1.

[0054] like Figure 8As shown, the waste heat recovery heating mode: when the passenger cabin temperature is low and the motor electric control loop heat is sufficient to meet the passenger cabin and power battery 13 heating requirements. At this time, the third three-way valve 21bc interface is connected, the second three-way valve 12ac interface is connected, the second four-way valve 8bc and ad interface is connected, the cooling liquid in the loop is heated by the motor electric control system 15 heat to warm the water tank 16, and the passenger cabin heating is realized. At the same time, the motor electric control loop cooling liquid enters the power battery loop through the second four-way valve 8 to heat the power battery 13. If the motor electric control loop heat cannot meet the passenger cabin and power battery 13 heating requirements at the same time, the passenger cabin uses the motor electric control loop waste heat recovery heating, and the power battery 13 uses the heat pump air conditioning heating.

[0055] As shown in the figure, Figure 9 PTC heating mode: when the passenger cabin temperature is low and the environment temperature is low, the compressor 1 reaches the highest speed but the heat pump air conditioner does not meet the heating requirements, and the PTC is used to heat the passenger cabin. At this time, the third three-way valve 21bc interface is connected, the second three-way valve 12ac interface is connected, the second four-way valve 8ab and cd interface is connected, the cooling liquid in the loop is heated by the second PTC 17 to warm the water tank 16, and the heat is exchanged with the air blown by the air blower 19, and finally enters the passenger cabin to realize heating.

[0056] As shown in the figure, Figure 10 The embodiment also provides an integrated thermal management method for an electric vehicle, which is realized by the above-mentioned integrated thermal management system for the electric vehicle, takes the cabin temperature as a state variable, takes the compressor speed, the PTC power and the waste heat mode as control variables for global optimization, and comprises the following steps: Step 1: system initialization, setting initial parameters and states; Step 2: sensor detection, obtaining various sensor data, including the passenger cabin temperature, the power battery pack temperature, the driving speed, the compressor speed and the like; Step 3: decision making, judging whether the passenger cabin temperature T b is lower than the set threshold value, if yes, starting the heating system; Step 4: determining the control variable, if the heating system needs to be started, firstly selecting the heating mode as the heat pump heating or the heat pump and PTC common heating according to the current working condition; according to the state and demand of the system, controlling the flow rate of the refrigerant, and determining the control variable that needs to be adjusted, namely the compressor speed and the PTC power and the waste heat mode switch; the change of the compressor speed affects the refrigerant flow in the system loop, and the change of the PTC power and the waste heat mode affects the heat source.

[0057] Step 5: MPC prediction model establishment, predicting the system behavior in a future period of time through a dynamic model, including the change of the passenger cabin temperature; Step 6: MPC optimization problem establishment, establish the optimization problem according to the prediction model, determine the cost function between the minimum control target and the constraint condition; Step 7: MPC optimization solution, solve the optimization problem to obtain the optimal control sequence, which includes the compressor speed, PTC power and waste heat mode switch in the future period of time; Step 8: Control execution, apply the optimal control sequence to the actual system, adjust the flow and pressure of the refrigerant in the system by adjusting the speed of the compressor; by adjusting the switch of the waste heat mode, the opening and closing of the waste heat recovery function are controlled. By controlling the compressor speed, PTC power and waste heat recovery mode, the energy consumption of the power battery is minimized while ensuring that the cabin temperature is within a certain range, achieving the balance between cabin comfort and power battery energy consumption.

[0058] In step 5, the MPC prediction model established is:

[0059] Wherein, k represents the current time, k+1 represents the next time, x(k) is the passenger cabin temperature at the current time, u(k) is the control variable at the current time, including compressor speed, PTC power and waste heat recovery mode. A and B are state matrix and control matrix.

[0060] In step 6, the control target is to keep the power battery pack temperature within a safe range and minimize energy consumption.

[0061] The cost function is:

[0062] Wherein, N is the prediction time domain length, T cabin (k) is the passenger cabin temperature at time k, T ref is the target temperature of the passenger cabin, u(k) is the control input at k, and α, β are the corresponding weight coefficients.

[0063] In step 7, an optimization solver is used to solve the optimization problem.

[0064] As can be seen, the pure electric vehicle thermal management system provided by the present application is a method, which has the following advantages compared with the traditional thermal management system: First, the present application utilizes the high efficiency of heat pump air conditioner and the waste heat heating function of motor electric control system to make the passenger cabin and power battery quickly reach the optimal temperature range, achieving the purpose of reducing the energy consumption of pure electric vehicle and improving the winter range of pure electric vehicle.

[0065] Second, the application uses model predictive control (MPC) algorithm to intelligently control the heating system of the electric vehicle, to predict the control of the compressor speed, PTC power and waste heat mode, and to fully utilize multiple heat sources for heating according to the working conditions in combination with the heating effect of the heating system. By establishing a dynamic system model, MPC can predict the behavior of the system in the future period of time, so that the controller can make adjustments in advance to adapt to possible changes in the future. MPC can handle various constraints such as safety constraints and performance constraints of the system, and the optimal solution obtained by the optimization solver can ensure that the system operates within a safe and effective range.

[0066] The above embodiment is only one of the implementation manners capable of implementing the technical scheme of the application, and the scope of protection claimed by the application is not limited to the embodiment, but also includes any changes, substitutions and other implementation manners easily thought of by those skilled in the art within the technical scope disclosed by the application.

Claims

1. A thermal management system for a pure electric vehicle, characterized in that: include: Integrated heat pump air conditioning system, power battery circuit and motor electronic control circuit; The heat pump air conditioning system is connected to the power battery circuit, and the power battery circuit is connected to the motor electronic control circuit; The heat pump air conditioning system can selectively switch to a cooling mode and a heating mode to cool or heat the passenger compartment and the power battery (13); The motor electronic control circuit is capable of recovering waste heat to heat the passenger compartment and the power battery (13); The heat pump air conditioning system comprises a compressor (1), a first four-way valve (6), an off-vehicle heat exchanger (2), an expansion component, and an on-vehicle heat exchange component; When the compressor (1) output port, the first passage of the first four-way valve (6), the off-vehicle heat exchanger (2), the expansion component, the on-vehicle heat exchange component, the second passage of the first four-way valve (6), and the compressor (1) input port form a passage, the heat pump air conditioning system switches to a cooling mode to cool the passenger compartment and the power battery (13); When the compressor (1) output port, the third passage of the first four-way valve (6), the in-vehicle heat exchange component, the expansion component, the out-vehicle heat exchanger (2), the fourth passage of the first four-way valve (6), and the compressor (1) input port form a passage, the heat pump air conditioning system switches to a heating mode to heat the passenger compartment and the power battery (13).

2. A thermal management system for a pure electric vehicle according to claim 1, characterized in that: The expansion assembly comprises a first electronic expansion valve (3) and a second electronic expansion valve (7); the in-vehicle heat exchange assembly comprises an in-vehicle heat exchanger (4) and a plate heat exchanger (9); the first electronic expansion valve (3) is connected between the out-vehicle heat exchanger (2) and the in-vehicle heat exchanger (4), and the second electronic expansion valve (7) is connected between the out-vehicle heat exchanger (2) and the plate heat exchanger (9); the plate heat exchanger (9) is connected to a power battery (13), and a working medium flow path of the in-vehicle heat exchanger (4) is arranged in the passenger compartment, and cold air is blown into the passenger compartment through a blower (19).

3. A thermal management system for a pure electric vehicle according to claim 1, characterized in that: The first four-way valve (6) comprises four interfaces a, b, c and d; wherein b and d form a first passage; c and a form a second passage; b and c form a third passage; and d and a form a fourth passage.

4. A thermal management system for a pure electric vehicle according to claim 1, characterized in that: The compressor (1) output port is connected to a gas-liquid separator (20).

5. A thermal management system for a pure electric vehicle according to claim 1, characterized in that: The power battery circuit is connected to the motor electronic control circuit via a second four-way valve (8); When the first passage and the second passage of the second four-way valve (8) are connected between the power battery circuit and the motor electronic control circuit, the power battery circuit and the motor electronic control circuit form a series passage, and the motor electronic control circuit can heat the passenger compartment and the power battery (13); When the third passage of the second four-way valve (8) is connected to the power battery circuit, and the fourth passage is connected to the motor electronic control circuit, the power battery circuit and the motor electronic control circuit operate independently.

6. A thermal management system for a pure electric vehicle according to claim 5, characterized in that: The second four-way valve (8) comprises four interfaces a, b, c and d; wherein c and b form a first passage; a and d form a second passage; a and b form a third passage; and c and d form a fourth passage.

7. A thermal management system for a pure electric vehicle according to claim 1, characterized in that: The power battery circuit comprises a power battery (13) and a first water pump (10); a portion of the in-vehicle heat exchange assembly is connected between the power battery (13) and the first water pump (10); a first PTC (14) is also provided on the power battery circuit; and the power battery circuit is connected to the motor electronic control circuit via a second four-way valve (8).

8. The thermal management system of a pure electric vehicle according to claim 1, characterized in that: The motor electronic control circuit includes a motor electronic control system (15), a second water pump (11) and a radiator (18); the motor electronic control circuit is connected to the power battery circuit via a second four-way valve (8); The motor electronic control system (15) is connected to the second water pump (11), and the motor electronic control system (15) is connected to the radiator (18) via the second three-way valve (12); The radiator (18) is also connected in sequence to a second PTC (17) and a heater water tank (16); The radiator (18) is connected to the second PTC (17) via a third three-way valve (21); The residual heat of the motor of the motor electronic control system (15) is used to heat the passenger compartment through the radiator (18) and the heater water tank (16).

9. A thermal management method for a pure electric vehicle, based on a thermal management system for a pure electric vehicle according to any one of claims 1 to 8, characterized in that: include: Initialize the thermal management system and set initial parameters and status; Get sensor data; Determine whether the passenger compartment temperature is below a set threshold based on initial parameters, status, and sensor data, and if so, activate the heating system; If the heating system is started, first select the heating mode based on the current working conditions: heat pump heating or heat pump and PTC heating. Then, control the refrigerant flow rate and determine the control variables that need to be adjusted based on the system status and needs. Establish an MPC prediction model and use it to predict system behavior within a preset time period in the future; Establish an optimization problem based on the MPC prediction model and determine the cost function between the control objective and the constraints to be minimized; Solve the optimization problem of the MPC prediction model to obtain an optimal control sequence, wherein the optimal control sequence includes the system behavior within a preset time in the future; Feedback the optimal control sequence to the actual thermal management system, specifically executing the following process: Regulate the flow and pressure of the refrigerant in the system by adjusting the speed of the compressor; Control the opening and closing of the waste heat recovery function by adjusting the waste heat mode switch; By controlling the compressor speed, PTC power and waste heat recovery mode.

10. A thermal management method for a pure electric vehicle based on waste heat recovery according to claim 9, characterized in that: in: The MPC prediction model is: Where k represents the current moment, k+1 represents the next moment; x(k) is the passenger compartment temperature at the current moment; u(k) is the control variable at the current moment, including compressor speed, PTC power, and waste heat recovery mode; A and B are the state matrix and control matrix; The cost function is: Among them, N is the length of the prediction time domain; T cabin (k) is the passenger compartment temperature at time k; T ref is the target temperature of the passenger compartment; u(k) is the control input at time k; α and β are the corresponding weight coefficients.

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