Electric vehicle thermal management system and vehicle

Abstract

The electric air-conditioning compressor, the electronic water pump, the heat dissipation fan, the electronic expansion valve, the stop valve, the water heating PTC and the air heating PTC are communicated with the VCU through a CAN / LIN network, and the cooling and heating cycles are cooperatively controlled according to the vehicle working condition, the temperature signal and the energy state, so that the precise temperature regulation of the battery, the electronic control and the passenger cabin is realized. When the battery temperature exceeds the set value, the system starts the electronic water pump and the compressor to cool; when the battery temperature is too low, the water heating PTC heating cycle is used to realize rapid heating; meanwhile, when the passenger cabin is refrigerated or heated, the compressor and the fan are adjusted according to the evaporator temperature and pressure signals. Through the multi-loop cooperative control, the energy utilization efficiency is improved, the battery and the electronic control life are prolonged, and the safety and stability of the thermal management system are enhanced. The application also discloses a vehicle.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicle thermal management technology. Specifically, this invention relates to an electric vehicle thermal management system and vehicle. Background Technology

[0002] With the increasing popularity of electric vehicles, the importance of their thermal management systems is becoming increasingly prominent. Thermal management systems directly affect the performance, safety, and battery life of electric vehicles. Existing electric vehicle thermal management systems suffer from problems such as poor coordination and control of various components, low energy utilization efficiency, and insufficient protection for critical components such as the battery and electronic control system.

[0003] For example, the inability to precisely control battery temperature during charging and discharging leads to decreased battery performance and shortened lifespan; and the inability to rationally allocate cooling and heating resources under different operating conditions results in energy waste.

[0004] An improved thermal management system for electric vehicles is provided, particularly concerning how to achieve precise temperature control of components such as electric vehicle batteries and electronic controls, thereby improving energy efficiency and extending the service life of batteries and electronic controls. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a thermal management system for electric vehicles, with the purpose of achieving precise temperature control of components such as the electric vehicle battery and electronic control system, thereby improving energy utilization efficiency and extending the service life of the battery and electronic control system.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an electric vehicle thermal management system, including a vehicle control unit, a battery management system, a three-in-one module, an electric air conditioning compressor, a first heater, a second heater, a first electronic water pump, a second electronic water pump and a cooling fan, wherein the first heater is arranged opposite to the evaporator, the second heater is disposed between the second electronic water pump and the power battery, and the first electronic water pump is connected to the drive motor. The vehicle control unit interacts with the battery management system, the three-in-one module, the electric air conditioning compressor, and each actuator through a communication network. Based on the vehicle's operating status, battery pack temperature, motor temperature, motor controller temperature, DC-DC temperature, and passenger compartment requirements, it controls the start / stop and operating power of the first electronic water pump, the second electronic water pump, the cooling fan, the electric air conditioning compressor, the first heater, and the second heater to achieve multi-loop coordinated temperature management of the power battery, electronic control components, and passenger compartment.

[0007] The vehicle control unit controls the activation of the first electronic water pump based on the motor temperature, the motor controller temperature, and the DC-DC temperature. The first electronic water pump is activated when any of the above temperatures is ≥45℃, and deactivated when any of the above temperatures is ≤40℃. The unit also adjusts the duty cycle of the first electronic water pump according to the gear and vehicle speed.

[0008] When the vehicle is charging or under high voltage, the battery management system determines whether the battery pack temperature has reached the cooling threshold. When the cooling or temperature equalization request is met, it sends a cooling request, a temperature equalization request, and target water temperature information to the vehicle control unit. The vehicle control unit responds to the request by controlling the opening status of the second electronic water pump, the shut-off valve, and the electronic expansion valve, and adjusting the speed of the electric air conditioning compressor to achieve cooling or temperature equalization control of the power battery.

[0009] The second electronic water pump operates using PWM control. When the activation conditions are met, its duty cycle is 86%. After the vehicle is powered off or charging is completed, if the difference between the highest temperature T1 and the lowest temperature T1' of the power battery is greater than 11°C and the SOC is greater than 5%, the second electronic water pump will remain on to perform temperature equalization control until the difference between the highest temperature T1 and the lowest temperature T1' of the power battery is less than or equal to 8°C or the second electronic water pump runs for 60 minutes and then shuts off.

[0010] The electric air conditioning compressor is located in the refrigerant circulation loop, which includes an electronic expansion valve, a condenser, and a battery cooler. The electronic expansion valve is located between the outlet of the condenser and the inlet of the battery cooler and is connected to both the condenser and the battery cooler. The battery cooler is connected to the power battery and the second electronic water pump. The electric air conditioning compressor is located between the inlet of the condenser and the outlet of the battery cooler and is connected to both the condenser and the battery cooler. The electronic expansion valve determines its initial opening degree by looking up a table based on the cooling power request from the battery management system, and then performs closed-loop adjustment based on the superheat ΔT. When ΔT < 3℃, the valve opening is reduced by 10 steps every 10 seconds, but not less than 50 steps. When ΔT > 10℃, the valve opening increases by 10 steps every 10 seconds and is limited by the upper limit of the opening.

[0011] The condenser is connected to the shut-off valve, which is connected to the thermostatic expansion valve, which is connected to the evaporator. The shut-off valve is a normally open solenoid valve. When the vehicle is under high pressure and there is a need for both battery cooling and passenger compartment cooling, the shut-off valve closes if the evaporator temperature is <1℃ or the battery pack maximum temperature is ≥55℃. The shut-off valve reopens when the evaporator temperature is ≥4℃ or the battery pack temperature is ≤53℃.

[0012] The shut-off valve is opened and closed based on vehicle status, air conditioning system, and power battery cooling requirements: ① When the vehicle is in the OFF position and enters the charging process, the VCU receives a cooling request from the BMS; ② After the vehicle is connected to high voltage, if there is a simultaneous need for battery cooling and cab cooling, the shut-off valve will close when the evaporator temperature is <1℃. The shut-off valve will reopen when the evaporator temperature is ≥4℃.

[0013] When the battery management system detects that the minimum temperature of the power battery T1' ≤ 5℃ and Tmean ≤ 16℃ and SOC ≥ 30%, the battery management system sends a thermal management heating request to the vehicle control unit. After the vehicle control unit controls the second electronic water pump to turn on, it sends an enable signal for the second heater after a 3-second delay, so that the second heater works at the rated power of 5kW until the outlet water temperature reaches 50℃, and then adjusts the heating power to maintain the temperature.

[0014] In charging conditions where both the passenger compartment and the power battery require cooling, the cooling of the power battery is the primary method, while the cooling of the passenger compartment is secondary. The maximum speed of the electric air conditioning compressor is set to 6000 rpm. When not charging, the system primarily cools the passenger compartment, with the electric air conditioning compressor set to a maximum speed of 4000 rpm.

[0015] The present invention also provides a vehicle including the aforementioned electric vehicle thermal management system.

[0016] The electric vehicle thermal management system of the present invention has the following significant advantages: 1. High system integration: Multiple heat sources and actuators are centrally controlled through VCU, forming a unified and coordinated thermal management network; 2. Energy utilization optimization: Dynamically allocate cooling / heating loads based on real-time operating conditions and temperature requirements to improve energy efficiency; 3. High control precision: By controlling the water pump speed with PWM and adjusting the opening of the electronic expansion valve in a closed loop, rapid temperature response and precise regulation are achieved; 4. Safe and reliable: Built-in fault protection and delay strategy to avoid overheating, adhesion and high voltage abnormalities, and improve system stability; 5. Adaptable to multiple operating conditions: It can operate stably under conditions such as driving, charging, and rapid power-on / off, while taking into account the temperature requirements of the battery, electronic control, and passenger compartment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the electric vehicle thermal management system of the present invention; Figure 2 This is a control relationship diagram for thermal management components; Figure 3 This is a block diagram of thermal management control; Figure 4 This is a block diagram of the crew cabin cooling system; Figure 5 This is a block diagram of the three-in-one cooling cycle control. Figure 6 This is a block diagram of the battery pack thermal management control. The markings in the above diagrams are as follows: 1. First electronic water pump; 2. Second electronic water pump; 3. Cooling fan; 4. First heater; 5. Second heater; 6. Electronic expansion valve; 7. Shut-off valve; 8. Thermal expansion valve; 9. Condenser; 10. Compressor; 11. Drive motor; 12. Three-in-one module; 13. Low-temperature radiator; 14. Power battery; 15. Battery cooler; 16. Charging valve; 17. Expansion tank; 18. Battery cooling degassing circuit; 19. Refrigerant circulation circuit; 20. Electric drive cooling circuit; 21. Battery cooling circuit; 22. Electric drive cooling degassing circuit; 23. Evaporator. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0019] It should be noted that in the following embodiments, the terms "first" and "second" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution, but are merely for the convenience of description.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Firstly, such as Figure 1As shown, this embodiment of the invention provides an electric vehicle thermal management system, including a vehicle control unit (VCU), a battery management system (BMS), a three-in-one module, a drive motor, an electric air conditioning compressor, a first heater, a second heater, a first electronic water pump, a second electronic water pump, a low-temperature radiator, and a cooling fan. The low-temperature radiator and the cooling fan are arranged opposite to each other, and the low-temperature radiator is located between the cooling fan and the condenser. The cooling fan is used to remove the heat generated by the low-temperature radiator and the condenser. The first heater is arranged opposite to the evaporator. The second heater is located between the second electronic water pump and the power battery. The first electronic water pump is connected to the drive motor. The vehicle control unit interacts with the battery management system, the three-in-one module, the electric air conditioning compressor, and various actuators via a communication network. Based on the vehicle's operating status, battery pack temperature, motor temperature, three-in-one module temperature, and passenger compartment requirements, it controls the start / stop and operating power of the first electronic water pump, the second electronic water pump, the cooling fan, the electric air conditioning compressor, the first heater, and the second heater to achieve multi-loop coordinated temperature management of the power battery, electronic control components, and passenger compartment.

[0022] Specifically, the present invention aims to provide an electric vehicle thermal management system to solve the problems of poor coordinated control of various components, low energy utilization efficiency, and insufficient protection of key components in the existing thermal management system, so as to achieve precise temperature control of electric vehicle battery, electronic control and other components, improve energy utilization efficiency, and extend the service life of battery and electronic control.

[0023] In embodiments of the present invention, such as Figure 1 As shown, in the motor cooling circuit, the outlet of the first electronic water pump is connected to the inlet of the three-in-one module, the outlet of the three-in-one module is connected to the inlet of the drive motor, the outlet of the drive motor is connected to the inlet of the low-temperature radiator, and the outlet of the low-temperature radiator is connected to the inlet of the first electronic water pump. The three-in-one module integrates a motor controller (MCU), a DC-DC power supply module (DCDC), and a high-voltage power distribution unit (PDU). The DC-DC temperature refers to the temperature of the DC-DC power supply module.

[0024] In embodiments of the present invention, such as Figure 1 As shown, in the battery cooling circuit, the outlet of the second electronic water pump is connected to the inlet of the second heater, the outlet of the second heater is connected to the inlet of the power battery, the outlet of the power battery is connected to the first inlet of the battery cooler, and the first outlet of the battery cooler is connected to the inlet of the second electronic water pump.

[0025] In embodiments of the present invention, such as Figure 1As shown, an electronic expansion valve, a condenser, and a battery cooler are installed in the refrigerant circulation loop. The electronic expansion valve is located between the outlet of the condenser and the inlet of the battery cooler and is connected to both. The outlet of the electric air conditioning compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the electronic expansion valve, the outlet of the electronic expansion valve is connected to the second inlet of the battery cooler, and the second outlet of the battery cooler is connected to the inlet of the electric air conditioning compressor. The battery cooler facilitates heat exchange between the refrigerant circulation loop and the battery cooling loop. The condenser is connected to a shut-off valve, which is connected to a thermostatic expansion valve, which is connected to the evaporator. The inlet of the shut-off valve is connected to the outlet of the condenser, the outlet of the shut-off valve is connected to the inlet of the thermostatic expansion valve, the outlet of the thermostatic expansion valve is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the inlet of the electric air conditioning compressor. The high-temperature, high-pressure refrigerant liquid flows through the thermostatic expansion valve and becomes a low-temperature, low-pressure refrigerant liquid. When this low-temperature, low-pressure refrigerant liquid flows through the evaporator, the evaporator evaporates it into low-temperature, low-pressure vapor. The first heater provides auxiliary heating when the heating capacity of the air conditioning heating cycle is low. The first heater heats the inlet air of the evaporator to increase the temperature of the air flowing through the warm air core.

[0026] like Figure 1 As shown, the thermal management system architecture of this invention is as follows: The electric vehicle thermal management system of this invention includes components such as a vehicle control unit (VCU), a battery management system (BMS), a motor controller (MCU), a DC-DC converter (DCDC), an electric air conditioning compressor (EAC), an electric water pump, a cooling fan, an electronic expansion valve, a shut-off valve, a first heater, and a second heater. The components interact with each other via communication networks such as CAN and LIN to achieve coordinated operation.

[0027] In this embodiment of the invention, the thermal management control of the crew cabin is as follows: Figure 4 As shown: In terms of passenger compartment cooling, the VCU obtains the required speed of the electric air conditioning compressor based on the driver's needs, the vehicle's operating conditions, and signals such as evaporator temperature and vehicle speed, combined with the power required for battery pack cooling, and controls the compressor to work.

[0028] When the vehicle is in the ON position and under high pressure, and the following conditions are met: air conditioning activation request, fan speed knob not at zero setting, and power limit > peak power for 200ms, the passenger compartment cooling is allowed to start. Simultaneously, by monitoring the evaporator temperature and AC pressure, the electric air conditioning compressor is protected. When the evaporator temperature is ≥4℃, the VCU sends an enable signal to the electric air conditioning compressor, allowing AC operation. When the evaporator temperature is <1℃, the VCU stops sending the enable signal and requests the compressor speed to drop to 0, disallowing AC operation. If the evaporator temperature is within the hysteresis range, the previous state is maintained. For fan control, the high and low speeds are controlled based on the electric air conditioning compressor enable and the three-state pressure switch status. When the high / low pressure switch is detected to be closed, the VCU sends an enable signal to the electric air conditioning compressor after a 3s delay, allowing AC operation. When the high / low pressure switch is detected to be open, the VCU stops sending the enable signal to the electric air conditioning compressor and requests the compressor speed to drop to 0, disallowing AC operation, thus achieving precise control of the electric air conditioning compressor speed. Similarly, when the passenger compartment is heated, if the vehicle is in the ON position and under high pressure, and the conditions such as a request to turn on the first heater are met, the passenger compartment PTC relay is fault-free, and the blower is turned on, the first heater is allowed to turn on to achieve passenger compartment heating.

[0029] In this embodiment of the invention, the cooling circulation system control of the three-in-one module (MCU, DC-DC, PDU) is as follows: Figure 5 As shown: During vehicle power-on, charging, and intelligent charging processes, when relevant vehicle components require cooling (including driving, charging, and intelligent charging), the low-temperature cooling system is activated. The VCU controls the first electronic water pump to operate based on the vehicle status and controller temperature. When the motor temperature, motor controller temperature, or DC-DC temperature reaches a set threshold, or when the gear and vehicle speed meet specific conditions, the water pump is turned on, and its speed is adjusted according to temperature changes. Simultaneously, the VCU calculates the cooling fan speed requirements of the MCU, DC-DC, and air conditioning system, and controls the cooling fan to operate according to the maximum requirement. When the vehicle is powered off, if the MCU and DC-DC temperatures exceed the set values, the cooling fan is delayed and shut off.

[0030] In this embodiment of the invention, the vehicle control unit controls the activation of the first electronic water pump based on the motor temperature (MoterTemperature, i.e., the temperature of the drive motor), the motor controller temperature (ControllerTemperature), and the DC-DC temperature (DCDC_RealityTemp). The first electronic water pump is activated when any of the above temperatures is ≥45℃, and deactivated when any of the above temperatures is ≤40℃. The duty cycle of the first electronic water pump is adjusted according to the gear and vehicle speed conditions.

[0031] The high-voltage state of a vehicle refers to the operating state after the electric vehicle completes the pre-charging process of the high-voltage system, the high-voltage relay closes, and high-voltage electricity can be safely transmitted in the high-voltage circuit to power high-voltage components such as the motor, electric air conditioning compressor, and PTC. The first electronic water pump will activate if any of the following conditions are met after the vehicle enters the high-voltage state (including charging and discharging high voltage); otherwise, it will not activate: Condition ① Motor temperature ≥ 45℃ (shut down at ≤ 40℃); Condition ② Motor controller temperature (IGBT temperature) ≥ 45℃ (shutdown at ≤ 40℃); Condition ③: DCDC temperature (DCDC_RealityTemp) ≥ 45℃ (≤ 40℃, off); Condition ④ The vehicle is in R or D gear, and the vehicle speed is at a duty cycle of -20 km / h≤V≤20km / h (PWM-45%, RPM 2700). Condition ⑤ The vehicle is in R or D gear, the vehicle speed is V≤-20km / h or V≥20km / h, and the duty cycle is (PWM-70%, speed 4100rpm). Condition ⑥ The VCU detected an abnormal temperature communication signal, duty cycle (PWM-95%, speed 5500rpm).

[0032] Condition ④ above applies when the vehicle is in forward (D) or reverse (R) mode. Triggering prerequisite: - Gear: You must engage R (reverse) or D (drive) gear, excluding P (park) and N (neutral) gears, to ensure that the gear is only activated when the vehicle is moving. - Speed ​​range: -20km / h ≤ V ≤ 20km / h. Where -20km / h corresponds to the reverse speed in R gear (the negative sign indicates the opposite direction), and 20km / h corresponds to the low speed in D gear, covering scenarios such as slow maneuvering and following other vehicles in congested traffic.

[0033] Turn on the first electronic water pump. The operating parameters of the first electronic water pump are set as follows: - Duty cycle (PWM): 45%. PWM (Pulse Width Modulation) is the core signal for controlling the speed of an electronic water pump. A 45% duty cycle indicates that the water pump is operating at a moderate to low power.

[0034] - Engine speed: 2700 rpm. This speed provides sufficient coolant circulation to meet the heat dissipation needs during low-speed driving.

[0035] When the vehicle is traveling at low speeds, the load on the motor, MCU, and DC-DC converter is low (for example, the motor does not need high power output), and the heat generation is relatively small. Therefore, there is no need to operate the water pump at full load. By operating it at a 45% duty cycle and a speed of 2700 rpm, the heat dissipation effect and energy consumption are balanced, avoiding unnecessary waste of electrical energy.

[0036] Condition ⑤ above refers to the enhanced water pump control under medium-to-high speed driving conditions. This is the cooling control logic for scenarios such as highway driving and rapid overtaking, and its triggering prerequisite is: - Gear: Also limited to R or D gear, only for driving conditions.

[0037] - Vehicle speed range: V ≤ -20km / h (high-speed reversing, such as rapid reversing in special scenarios) or V ≥ 20km / h (high-speed forward). At this time, the vehicle is traveling at medium to high speed, and the motor needs to output more power (such as maintaining high speed or acceleration). The workload of MCU and DCDC also increases accordingly, and the heat generation increases significantly.

[0038] Turn on the first electronic water pump. The operating parameters of the first electronic water pump are set as follows: - Duty cycle (PWM): 70%. Compared to 45% in condition ④, the duty cycle is increased by 55%, which means that the power supply pulse width of the water pump is increased and the drive power is enhanced.

[0039] - Speed: 4100 rpm. The speed is about 52% higher than in condition ④, resulting in faster coolant circulation and more efficient removal of heat generated by the three-in-one module.

[0040] When a vehicle is traveling at high speeds, the heat generated by components is positively correlated with vehicle speed and load (for example, the motor continuously outputs high power during high-speed cruising). If the water pump speed is maintained at a low speed, heat may accumulate, affecting component performance and even triggering overheat protection. Therefore, by increasing the water pump speed, cooling capacity is enhanced to ensure that component temperatures remain stable within a safe range.

[0041] Condition ⑥ above is the emergency control of the water pump when temperature communication is abnormal. It is for abnormal scenarios where the VCU cannot obtain an accurate temperature signal. The triggering prerequisite is: - The VCU detects an anomaly in the temperature communication signal. Specifically, this includes issues such as signal interruption, data errors, and delays (e.g., CAN bus communication failure) when modules like the BMS (Battery Management System), MCU (Motor Controller), and DCDC send temperature data to the VCU. In this situation, the VCU cannot determine the actual temperature of the three-in-one module, posing a risk of undetected overheating.

[0042] Turn on the first electronic water pump. The operating parameters of the first electronic water pump are set as follows: - Duty cycle (PWM): 95%. Approaching the maximum duty cycle means the pump is operating at near full power.

[0043] - Speed: 5500 rpm. This is the maximum design speed of the water pump, providing maximum coolant flow and heat dissipation capacity.

[0044] When temperature communication fails, the vehicle employs a conservative worst-case scenario strategy—assuming the component is likely already overheating. By operating the water pump at maximum speed, it maximizes cooling and prevents component burnout or performance degradation due to temperature runaway. This is a typical safety-first design, prioritizing the safety of high-voltage components even at the cost of some energy consumption.

[0045] Vehicle power-off refers to the vehicle completing the high-voltage system disconnection process (relay disconnection, high-voltage circuit de-energization) and exiting high-voltage-related operating conditions such as driving and charging (e.g., driver locking the vehicle, completion of power-off command execution). After vehicle power-off, the first electronic water pump will shut off after a 10-second delay if any of the following conditions are met: Condition ①: Motor temperature ≥ 45℃; Condition ② The motor controller temperature is ≥45℃; Condition ③ DCDC temperature (DCDC_RealityTemp) ≥ 45℃.

[0046] When the vehicle is powered off, if the above condition ① is met and the motor temperature is ≥45℃, the first electronic water pump will be triggered to shut off after a 10-second delay. After power-off, the drive motor will no longer generate new heat. However, if the residual temperature is too high, such as ≥45℃, long-term static storage may cause aging of the winding insulation layer and a decrease in the performance of the bearing grease. In this case, it is necessary to continue to dissipate heat through coolant circulation until the temperature drops to a safe range.

[0047] When the vehicle is powered off, if condition ② above is met and the motor controller temperature is ≥45℃, the first electronic water pump will be triggered to shut off after a 10-second delay. After power-off, the coolant will continue to circulate to dissipate heat until the motor controller temperature drops to a safe range.

[0048] When the vehicle is powered off, if condition ③ above is met and the DCDC temperature is ≥45℃, the first electronic water pump will be triggered to shut down after a 10-second delay. If the residual heat of the DCDC core components is ≥45℃ after power-off, it may cause the internal insulation material to age. In this case, it is necessary to continue to dissipate heat through coolant circulation until the DCDC temperature drops to a safe range.

[0049] When the vehicle is charging or under high voltage, the battery management system determines whether the battery pack temperature has reached the cooling threshold. When the cooling or temperature equalization request is met, it sends the cooling request, temperature equalization request, and target water temperature information to the vehicle control unit. The vehicle control unit responds to the request by controlling the opening status of the second electronic water pump, the shut-off valve, and the electronic expansion valve, and adjusting the speed of the electric air conditioning compressor to achieve power battery cooling or temperature equalization control.

[0050] Regardless of which of the above conditions is met, the first electronic water pump will not shut down immediately after power-off, but will continue to run for 10 seconds. The purpose of this 10 seconds is to allow the coolant to continue circulating, transferring the residual heat from the motor, MCU, and DC-DC converter to the low-temperature heat sink, which will then dissipate the heat through natural wind or cooling fan airflow, thus preventing heat buildup inside the components.

[0051] In this embodiment of the invention, the battery pack thermal management system controls, as follows: Figure 6 As shown: Regarding liquid cooling, after the vehicle enters the charging process or reaches high voltage, the BMS determines that the battery pack temperature has reached a threshold and sends a cooling request, a temperature equalization request, and a target water temperature to the VCU. The VCU then controls the second electronic water pump, the shut-off valve, and the electronic expansion valve based on the requests, and controls the speed of the electric air conditioning compressor.

[0052] The second electronic water pump operates using PWM control. When the activation conditions are met, its duty cycle is 86%. After the vehicle is powered off or charging is completed, if the difference between the highest temperature T1 and the lowest temperature T1' of the power battery is greater than 11℃ and the SOC is greater than 5%, the second electronic water pump remains on to perform temperature equalization control until the difference between the highest temperature T1 and the lowest temperature T1' of the power battery is ≤8℃ or the second electronic water pump has been running for 60 minutes, at which point it shuts off. Specifically, the following activation conditions must be met for the control of the second electronic water pump: Condition ①: The duty cycle of the second electronic water pump is controlled at 86%. Condition ② After the vehicle is powered off or charging is completed, if the temperature difference T1 - T1' > 11℃ and SOC > 5%, the BMS will send a temperature equalization request to keep the second electronic water pump on until the temperature difference T1 - T1' ≤ 8℃ or lasts for 60 minutes, after which the second electronic water pump will be turned off.

[0053] Condition ③ The second electronic water pump and the electric air conditioning compressor are turned on for 3 seconds. After the compressor is turned off, the second electronic water pump will be turned off after a delay of 10 seconds and then work with the set duty cycle. After the vehicle is powered off or finished charging, the temperature is controlled according to the temperature difference and SOC.

[0054] When the power battery requires active cooling or heating, the VCU receives the cooling / heating request from the BMS and activates the second electronic water pump to enter normal operating mode. In condition ① above, the 86% duty cycle is the optimal calibration value for the second electronic water pump under the condition of effective heat transfer and energy consumption balance. PWM controls the water pump motor speed by adjusting the pulse duty cycle of the electrical signal. An 86% duty cycle corresponds to the water pump's rated speed. According to the system design, this speed ensures that the coolant flow rate meets the maximum heat exchange requirements of the power battery, such as quickly removing battery heat during cooling and uniformly transferring heat from the PTC during heating. During the active thermal management phase of the battery, a fixed high duty cycle ensures the coolant circulation speed and heat transfer efficiency, avoiding both insufficient heat exchange due to low flow rate and energy waste due to excessive flow rate.

[0055] In condition ② above, after the vehicle finishes driving and is powered off (e.g., the driver locks the vehicle) or charging ends (the charging pile is disconnected), the BMS continuously monitors the temperature difference between the highest temperature (T1) and the lowest temperature (T1') inside the power battery. If the temperature difference is greater than 11℃ and the battery's state of charge (SOC) is greater than 5%, a temperature equalization request is sent to the VCU, and the second electronic water pump remains on. When the temperature difference drops to ≤8℃, the battery temperature uniformity meets the standard, or the water pump has been running continuously for 60 minutes, the second electronic water pump is turned off to avoid excessive power consumption. Considering that uneven temperature distribution inside the power battery (excessive temperature difference) can lead to differences in the charging and discharging efficiency and aging speed of each cell, it will seriously affect the battery's consistency and service life in the long run. After the vehicle is powered off / charging ends, although the battery stops charging and discharging, residual heat or low temperature may cause local temperature differences to remain. By continuing to circulate the coolant through the water pump, local temperature differences can be eliminated by liquid convection, ensuring the overall temperature uniformity of the power battery. The requirement that the SOC of the power battery be greater than 5% is to avoid excessive consumption of the low-voltage or high-voltage battery during the temperature equalization process, which could prevent the vehicle from failing to start or the battery from being deeply discharged and affecting its lifespan. The 60-minute limit is to balance the temperature equalization effect and energy consumption. If the temperature difference is still not met after 60 minutes, the battery will be forcibly shut down to prevent it from being depleted.

[0056] In condition ③ above, the second electronic water pump and the electric air conditioning compressor are controlled in tandem. When the power battery needs cooling, the second electronic water pump and the electric air conditioning compressor work together. The compressor provides cooling, and the water pump drives the coolant to absorb the cooling energy through the battery cooler before entering the power battery. The second electronic water pump and the electric air conditioning compressor start synchronously and maintain coordinated operation for the first 3 seconds to ensure that the coolant has started circulating after the electric air conditioning compressor starts, preventing local overcooling of the refrigerant in the battery cooler due to lack of coolant flow. After the electric air conditioning compressor is turned off, the second electronic water pump does not turn off immediately but delays for 10 seconds to continue driving the coolant circulation, carrying the residual cooling energy in the battery cooler into the power battery (avoiding waste of cooling energy) and preventing a sudden increase in pipeline pressure caused by the sudden shutdown of the electric air conditioning compressor. If the vehicle is powered off or charging ends at this time, the system automatically switches to the temperature equalization control logic of condition ② (determining whether to continue turning on the water pump based on the temperature difference and SOC). This setup ensures the coordinated stability of the entire cooling system's startup, operation, and shutdown process, preventing system failures (such as localized icing or pressure surges) caused by asynchrony between the water pump and compressor. It also maximizes the utilization of cooling capacity, improving energy efficiency and system safety.

[0057] In this embodiment of the invention, the shut-off valve is opened and closed according to the vehicle status, the air conditioning system, and the cooling requirements of the power battery: ① When the vehicle is in the OFF position and enters the charging process, the VCU receives a cooling request from the BMS; ② When the vehicle is under high voltage and there is a simultaneous need for battery cooling and cab cooling, the shut-off valve will close if the evaporator temperature is <1℃. The shut-off valve will reopen when the evaporator temperature is ≥4℃. (The shut-off valve will close if the battery pack temperature is ≥55℃, and open if the battery pack temperature is ≤53℃). ③ When the vehicle is under high voltage (HV_Ready / PT_Ready), and there is no AC request from the cab but the battery needs cooling, the shut-off valve will close. When the vehicle is under high voltage (including high voltage during charging and discharging), the VCU receives a cooling request from the BMS and the second electronic water pump starts, opening the electronic expansion valve.

[0058] like Figure 1 As shown, the shut-off valve is connected in series between the condenser and the thermostatic expansion valve, and its opening and closing state directly determines whether the refrigerant enters the evaporator in the passenger compartment. In the above control condition ①, after the vehicle is turned off (OFF position) and connected to the charging pile, there is no need for cooling in the passenger compartment, but the power battery needs to be cooled due to the heat generated during charging. The BMS sends a cooling request, the shut-off valve closes, and the refrigerant does not flow through the shut-off valve.

[0059] Under control condition ② above, after the vehicle is powered by high voltage, there are simultaneous cooling needs for the power battery and the passenger compartment. Therefore, the opening and closing of the shut-off valve needs to be controlled. At this time, the shut-off valve is closed when the evaporator temperature is <1℃ and opened when the evaporator temperature is ≥4℃. When the evaporator temperature is <1℃, the shut-off valve closes, suspending the supply of refrigerant to the evaporator in the passenger compartment; it reopens when the temperature rises to ≥4℃ to prevent the evaporator from freezing due to continuous cooling. This temporary cut-off of refrigerant protects the passenger compartment cooling system, and cooling is resumed once the temperature is safe. Furthermore, the shut-off valve closes when the maximum power battery temperature is ≥55℃ and opens when the maximum power battery temperature is ≤53℃. When the battery overheats, the shut-off valve closes, suspending cooling to the passenger compartment; it reopens when the temperature drops to ≤53℃ (safe range). This prioritizes cooling the battery when it is high, preventing the battery from triggering protection due to overheating, and ensuring vehicle power performance and battery safety.

[0060] Under control condition ③ above, after the vehicle is powered by high voltage, there is no AC request in the cab (occupants do not need cooling), but the battery requires cooling, so the control shut-off valve is closed. At this time, the passenger compartment does not require cooling, and closing the shut-off valve can prevent refrigerant from flowing into the evaporator ineffectively (the evaporator is not working at this time, and refrigerant retention will lead to abnormal pressure), so that all the refrigerant is used for the battery cooling circuit, reducing energy loss.

[0061] When the vehicle is under high pressure (including high pressure during charging and discharging), the VCU receives a cooling request from the BMS and the second electronic water pump is activated, opening the electronic expansion valve to ensure that the coolant in the battery cooling circuit has started circulating.

[0062] In this embodiment of the invention, regarding the control of the electric air conditioning compressor speed: ① When the battery pack has cooling requirements, the electric air conditioning compressor speed control is based on the target water temperature required by the BMS. Assuming the battery cooler evaporation temperature is 3°C, the maximum speed of the electric air conditioning compressor is 6000 rpm, and the estimated system cooling capacity is 5.4 kW. ② When both the passenger compartment and the battery pack have cooling requirements, under charging conditions, the cooling requirements of the battery pack are prioritized, with passenger compartment cooling as a secondary measure. Under the proposed maximum cooling load requirement: the target water temperature of the passenger compartment is set at 1500W, and the target water temperature of the battery cooler is 4000W (achieved through calibration of the battery cooler superheat target value). The electric air conditioning compressor speed is executed according to the BMS cooling requirements, with a maximum speed of 6000 rpm. When the vehicle is not in charging conditions, the cooling requirements of the battery pack are secondary, with passenger compartment cooling as the primary measure. The electric air conditioning compressor speed adjustment is mainly based on the passenger compartment temperature control strategy, with a maximum speed of 4000 rpm and an estimated system cooling capacity of 3.6 kW.

[0063] Under control condition ① above, speed control is implemented only when the power battery requires cooling. When the vehicle has no passenger compartment cooling request (e.g., the driver leaves while charging, or the air conditioning is not on while driving), but the power battery needs cooling due to charging / discharging or excessively high ambient temperature, the BMS sends a cooling request. The core adjustment is based on the target coolant temperature requested by the BMS. The target coolant temperature is the ideal cooling water temperature calculated by the BMS based on the current battery temperature. For example, if the current power battery temperature is 35℃ and the target coolant temperature is 25℃, the electric air conditioning compressor needs to output the corresponding cooling capacity to lower the coolant temperature to 25℃. The evaporation temperature of the battery cooler is set to 3℃, which is the optimal value for heat exchange between the refrigerant and coolant: too low a temperature can easily cause the battery cooler to freeze, while too high a temperature will result in insufficient heat exchange efficiency. The maximum speed of the electric air conditioning compressor is limited to 6000rpm, corresponding to a maximum system cooling capacity of approximately 5.4KW. This parameter is calibrated based on the maximum heat dissipation requirement of the battery and can meet the rapid cooling needs of the battery under fast charging or high temperatures.

[0064] In control condition ② above, the engine speed is controlled when both the passenger compartment and the power battery have cooling needs simultaneously. This is achieved by prioritizing different operating conditions. When both require cooling, the core of the electric air conditioning compressor speed control is to determine the priority based on the operating conditions. By limiting the maximum speed and allocating the cooling load, the core needs under different scenarios are balanced. For example, when the vehicle is charging, such as with fast charging, the battery generates heat due to the high current and needs cooling. Simultaneously, passengers may be inside the vehicle waiting for charging and turning on the air conditioning. The target cooling capacity for the passenger compartment is 1500W to meet basic cooling requirements, while the target cooling capacity for the battery is 4000W, prioritizing battery heat dissipation. The total load is 5500W, close to the system's maximum cooling capacity of 5.4KW, taking into account actual losses. The electric air conditioning compressor speed is adjusted entirely according to the BMS's cooling requirements, prioritizing the battery's target water temperature. The maximum speed remains at 6000rpm to ensure the battery receives maximum cooling capacity. This is achieved by calibrating the superheat target value of the battery cooler. Superheat is the difference between the refrigerant's temperature when it leaves the battery cooler and its saturation temperature. The lower the superheat, the more efficient the heat exchange of the refrigerant in the battery cooler, allowing more cooling capacity to be allocated to the battery.

[0065] When the vehicle is in motion, the driver turns on the air conditioning, requiring cooling in the passenger compartment. Simultaneously, the battery, due to the high load on the drive motor, generates heat and also requires cooling. The electric air conditioning compressor speed is adjusted primarily based on the passenger compartment temperature control strategy, taking into account factors such as the set temperature, evaporator temperature, and vehicle speed, prioritizing passenger comfort. At this time, the electric air conditioning compressor's maximum speed drops to 4000 rpm, corresponding to a maximum system cooling capacity of approximately 3.6 kW, lower than during charging. After meeting the basic cooling needs of the passenger compartment, the remaining cooling capacity is allocated to the battery; that is, battery cooling is not prioritized. This balances passenger comfort with minimizing impact on range, achieving a balance between comfort and vehicle range.

[0066] In terms of liquid thermal management, when the vehicle is in discharge mode, the BMS continuously monitors the battery temperature. When the battery's minimum temperature T1' ≤ 5℃, Tmean ≤ 16℃, and T1 ≤ 40℃, and the SOC ≥ 30%, the BMS's discharge fault level is < 3, and the difference between the battery's minimum and maximum temperatures is < 12℃, the BMS sends a thermal management heating request to the VCU. The VCU responds to the request by sending a thermal management enable signal, controlling the second electronic water pump to start, and sending an enable signal to the second heater 3 seconds after the second electronic water pump starts, along with the second electronic water pump's duty cycle and maximum power limit signals. Upon receiving the signals, the second heater starts working at its rated power of 5kW. When the battery's outlet temperature reaches 50℃, the second heater adjusts its heating power to maintain the battery's inlet water temperature at 50℃. The BMS receives the second heater's operating status and power consumption signals. If the second heater receives a BMS_WorkingMode signal of 0011, its power limit is the VCU's maximum power limit signal. When the power battery temperature is heated to T1'≥10℃ or Tmean≥18℃ or T1≥45℃, the BMS stops the heating request. After receiving the request, the VCU delays for 3 seconds to shut down the second electronic water pump and sends a second heater de-enable signal.

[0067] During the control process of the second heater mentioned above, the BMS sends a heating request only if all of the following conditions are met simultaneously. All conditions are indispensable to ensure that the heating demand is realistic and the system is in a safe state: (1) Setting the temperature conditions for the power battery: The lowest temperature of the power battery T1'≤5℃: When the temperature is ≤5℃, the discharge capacity and charging efficiency will drop significantly, which is the key temperature threshold for triggering heating. The average temperature of the power battery, Tmean, is ≤16℃: This avoids false triggering when the lowest local temperature meets the standard but the overall temperature is sufficient. For example, if some cells are low in temperature, the overall average temperature already meets the usage requirements, ensuring that heating is applied to the entire battery. Maximum battery temperature T1≤40℃: This prevents localized overheating of cells before heating. If T1≥40℃, heating will exacerbate the risk of high temperature, thus avoiding the potential for thermal runaway from the source.

[0068] (2) System safety settings to avoid secondary problems caused by heating: Power battery SOC≥30%: Heating requires electrical energy. The second heater has a rated power of 5kW. SOC≥30% can prevent the battery charge from being too low after heating. If it is lower than 10%, the vehicle will not be able to start or the driving range will be reduced sharply. BMS discharge fault level < 3: When the fault level is ≥ 3, the battery may have problems such as leakage or abnormal voltage. Heating at this time will increase the electrical safety risk, such as short circuit, so triggering is prohibited. Battery temperature difference, T1-T1'<12℃: If the temperature difference is ≥12℃, it indicates that the temperature distribution inside the battery pack is extremely uneven. Heating will further increase the temperature difference. For example, if the low-temperature battery cell absorbs heat, the high-temperature battery cell will continue to heat up, which will exacerbate the deterioration of the cell consistency.

[0069] During the control process of the second heater mentioned above, after receiving the heating request from the BMS, the VCU needs to execute actions in a fixed sequence. The key is to first establish coolant circulation and then start heating to avoid dry burning of components. (1) First, turn on the second electronic water pump: The VCU first sends a command to turn on the second electronic water pump to ensure that the coolant starts circulating; (2) Start the second heater after a 3-second delay: The VCU sends an enable signal to the second heater 3 seconds after the second electronic water pump is turned on, and simultaneously sends the following two key parameters: Duty cycle of the second electronic water pump: Control the speed of the second electronic water pump to ensure a stable coolant flow rate, such as the 86% duty cycle mentioned above, to meet the heat transfer requirements; Maximum power limit signal: Limits the maximum output power of the second heater, such as to avoid overloading the vehicle's low-voltage system and prevent electrical faults caused by excessive power.

[0070] After the second heater is activated, it ensures stable heat transfer to the power battery through a triple logic of rated power heating, constant temperature regulation, and power limiting. 1. Initial heating stage: The second heater operates at a rated power of 5kW to quickly raise the coolant temperature. The 5kW is the optimal power based on the thermal capacity of the power battery pack, which can raise the coolant from a low temperature to the target temperature in a short time and avoid excessively low heating efficiency. 2. Constant Temperature Regulation Stage: When the coolant outlet temperature of the power battery reaches 50℃, the power of the second heater is adjusted, such as reducing it from 5kW to 2-3kW, to maintain the power battery inlet water temperature stable at 50℃. If the heater receives the BMS_WorkingMode=0011 signal from the BMS, which is usually a mode where the power battery load is high or the system voltage fluctuates, it will operate according to the maximum power limit set by the VCU to avoid the heater competing with the power battery for power and causing voltage instability.

[0071] When the power battery temperature reaches the standard or a safety risk occurs, the system shuts down the second heater in the order of stop request - delayed pump shutdown. The trigger condition for the second heater to stop heating is that any of the following conditions are met: (1) T1'≥10℃: The minimum temperature of the power battery meets the standard. When the temperature is above 10℃, the activity of the power battery basically meets the usage requirements. (2) Tmean≥18℃: The overall average temperature of the power battery meets the standard and no further heating is required; (3) T1≥45℃: To prevent the maximum temperature of the power battery from being too high, 45℃ is close to the upper limit of the normal operating temperature of the power battery, and to avoid local overheating caused by heating.

[0072] After the BMS sends a stop heating request, the VCU does not immediately shut down the pump. Instead, it shuts down the second electric water pump after a 3-second delay after turning off the second heater. At the same time, it sends a heater de-enable signal. By setting a 3-second delay, the residual heat of the heater is carried away. After the heater stops working, the casing is still hot, which prevents the residual heat from baking the surrounding components. At the same time, the remaining high-temperature coolant in the pipeline is sent to the power battery to make full use of the waste heat and reduce energy waste.

[0073] In the aforementioned control process, the second heater's heating function is only activated when conditions such as SOC, fault level, and temperature difference are simultaneously met, avoiding false triggering in dangerous scenarios such as low temperature but low battery or low temperature but fault. Simultaneously, the system controls the water pump to start first, followed by the heater, and delays pump shutdown upon stopping, fundamentally preventing the heater from dry-burning and residual heat damaging components. Delaying pump shutdown upon stopping heating transfers residual heat to the power battery, preventing heat waste and indirectly reducing total heating energy consumption. This ensures power battery consistency and extends overall lifespan. Furthermore, the system exhibits strong coordination, adapting to complex operating conditions. The MS continuously monitors the power battery status, and the VCU dynamically adjusts the water pump and heater parameters, avoiding the lag inherent in single-module control.

[0074] Simultaneously, faults during the discharge heating process are addressed, and cross-condition handling strategies are developed to ensure stable system operation. ① Discharge heating fault handling: During the discharge heating process, if the water temperature inside the power battery exceeds 60℃, the BMS requests to stop heating but does not report a fault; if the water temperature exceeds 70℃, the BMS reports a second heater heating abnormality fault (high temperature, new level 3 fault). When processing the battery's maximum output power, the VCU takes the power of the second heater into account to avoid triggering an overcurrent fault.

[0075] For example, when the water temperature in the power battery is detected to exceed 70°C, the BMS sends a fault signal to the VCU. Upon receiving the signal, the VCU immediately controls the second heater to stop working and takes corresponding cooling measures, such as increasing the flow rate of the second electronic water pump to force-cool the power battery and ensure its safety.

[0076] ② Cross-condition handling: When power is restored after the key is off, the VCU detects high-voltage accessory drive signals (VCU_PTCEn, VCU_AcOn) and, after determining that the main positive and main negative relays are closed, sends high-voltage accessory enable signals (PTC enable signal VCU_bPTCRelaySts and electric air conditioning compressor drive request VCU_EAC_drive_reques) after a 100ms delay, effectively resolving the after-sales main positive sticking issue. When heating is required while driving, whether it's normal power-on or rapid power-off, the BMS, upon receiving the VCU power-on command, follows a pre-charge process. After high-voltage power-on, the VCU sends a second heater enable signal after a 10s delay; upon receiving the VCU power-off command, the BMS sends a second heater de-enable signal and controls the high-voltage relay to disconnect. For example, when heating is required while the vehicle is in motion, the BMS performs a pre-charge process according to the procedure to ensure stable system startup, and the VCU sends an enable signal at an appropriate time to ensure the second heater works normally; when the vehicle is powered off, the BMS promptly controls the second heater to stop working, ensuring system safety.

[0077] like Figure 1 As shown, the electronic expansion valve is located between the condenser and the battery cooler. In this embodiment of the invention, the initial opening of the electronic expansion valve is determined by the vehicle control unit based on the cooling power request from the battery management system, and then closed-loop adjustment is performed based on the superheat ΔT. When ΔT < 3℃, the valve opening is reduced by 10 steps every 10 seconds, but not less than 50 steps. When ΔT > 10℃, the valve opening increases by 10 steps every 10 seconds and is limited by the upper limit of the opening.

[0078] When the BMS sends a power battery cooling request to the VCU, the VCU first queries a preset power-opening table based on the requested power to determine the initial opening of the electronic expansion valve. Superheat ΔT refers to the actual temperature (T0) of the refrigerant when it leaves the battery cooler. 实 ) and the saturation temperature of the refrigerant at that pressure (T) 饱 The difference (ΔT=T) 实 -T 饱 ( ) is a key indicator reflecting the degree to which the refrigerant evaporates fully in the battery cooler.

[0079] If ΔT is too small (e.g., <3℃): it indicates that the refrigerant has not evaporated sufficiently, and if it enters the compressor, it is likely to cause liquid slugging. If ΔT is too large (e.g., >10℃): it indicates that the refrigerant has evaporated excessively, there is insufficient refrigerant in the battery cooler, the heat exchange area is not fully utilized, the cooling capacity is insufficient, and the power battery cools down slowly.

[0080] Therefore, the electronic expansion valve dynamically corrects its opening degree through feedback ΔT, according to the following rules: 1. When ΔT < 3℃, reduce the opening of the electronic expansion valve by 10 steps every 10 seconds, and the opening must not be less than 50 steps to achieve lower limit protection. After reducing the opening of the electronic expansion valve, the amount of refrigerant entering the battery cooler decreases, and the refrigerant has more time to evaporate in the battery cooler, causing ΔT to increase and move closer to the reasonable range.

[0081] The lower limit is set at 50 steps to avoid the refrigerant flow becoming zero and losing cooling capacity due to excessively small opening, ensuring that even at the minimum opening, there is still a basic cooling capacity to meet the heat dissipation needs of the power battery.

[0082] 2. When ΔT > 10℃, increase the opening of the electronic expansion valve by 10 steps every 10 seconds, but the opening must not exceed the upper limit. Increasing the opening of the electronic expansion valve increases the amount of refrigerant entering the battery cooler, allowing more refrigerant to evaporate within the battery cooler, fully utilizing the heat exchange area, increasing the cooling capacity, and thus reducing ΔT, bringing it closer to a reasonable range.

[0083] 3. When 3℃≤ΔT≤10℃, the electronic expansion valve maintains the current opening to avoid frequent operation due to small fluctuations.

[0084] In this embodiment of the invention, the shut-off valve is a normally open solenoid valve. When the vehicle is under high pressure and there is a simultaneous need for battery cooling and passenger compartment cooling, if the evaporator temperature is <1℃ or the battery pack maximum temperature is ≥55℃, the shut-off valve closes; when the evaporator temperature is ≥4℃ or the battery pack temperature is ≤53℃, the shut-off valve reopens.

[0085] When the battery management system detects that the minimum temperature of the power battery T1' is ≤5℃ and Tmean is ≤16℃ and SOC is ≥30%, the battery management system sends a thermal management heating request to the vehicle control unit. After the vehicle control unit controls the second electronic water pump to turn on, it sends an enable signal for the second heater after a 3-second delay, so that the second heater works at the rated power of 5kW until the outlet water temperature reaches 50℃, and then adjusts the heating power to maintain the temperature.

[0086] In charging conditions where both the passenger compartment and the power battery require cooling, the power battery cooling is the primary method, with passenger compartment cooling as a secondary method, and the maximum speed of the electric air conditioning compressor is set to 6000 rpm; in non-charging conditions, passenger compartment cooling is the primary method, and the maximum speed of the electric air conditioning compressor is set to 4000 rpm.

[0087] In this embodiment of the invention, the thermal management system, through the coordinated operation of its various components, regulates the temperature of different parts of the vehicle, ensuring vehicle performance, safety, and component lifespan. The specific functions of each component in the thermal management system architecture will be described in detail below.

[0088] Vehicle Control Unit (VCU): As the core control component of the thermal management system, the VCU receives signals from various sensors and control modules, such as temperature signals from the BMS, MCU, and DC-DC converters, as well as vehicle operating condition signals like vehicle speed and air conditioning activation requests. Based on these signals, the VCU controls the operating status of components such as the electric water pump, cooling fan, electric air conditioning compressor, electronic expansion valve, shut-off valve, and PTC according to preset control logic. During passenger compartment cooling, it combines evaporator temperature, vehicle speed, and battery pack cooling power requirements to determine the required speed of the electric air conditioning compressor and control its operation. In battery pack thermal management, it controls the water pump, valves, and electric air conditioning compressor according to BMS requests to achieve precise regulation of battery temperature.

[0089] The Battery Management System (BMS) is primarily responsible for monitoring parameters such as battery pack temperature, charge level, and voltage. Based on the battery pack temperature, the BMS sends cooling, equalization, or heating requests to the Voltage Control Unit (VCU), providing information such as the target water temperature. During charging and discharging, the BMS accurately determines whether cooling, heating, or equalization functions need to be activated based on battery temperature and temperature difference, and promptly sends corresponding requests to the VCU to ensure the battery remains within its optimal operating temperature range, thereby improving battery performance and extending battery life. During fast charging, if the battery's maximum temperature exceeds a threshold, the BMS sends a cooling request to the VCU to ensure the battery's cooling needs are met.

[0090] The motor controller (MCU) and DC-DC converter (DCDC) module: The MCU controls the motor's operation and generates heat during operation. The DCDC is responsible for converting high-voltage DC to low-voltage DC to power the vehicle's low-voltage electrical system, and also generates heat during operation. When the MCU and DCDC temperatures are too high, their performance and reliability will be affected, and may even lead to malfunctions. The thermal management system cools the MCU and DCDC using a first electric water pump and a cooling fan to ensure they operate within a suitable temperature range. When the MCU temperature is ≥45℃ (≤40℃ shutdown) or the DCDC temperature is ≥45℃ (≤40℃ shutdown), the first electric water pump activates, circulating coolant to remove heat. If the temperature continues to rise, the cooling fan will also activate for auxiliary cooling based on temperature and other conditions.

[0091] The Electric Air Conditioning Compressor (EAC) plays a crucial role in both passenger compartment and battery pack cooling. When cooling the passenger compartment, the EAC operates according to the control signals from the Vehicle Cooling Unit (VCU), compressing the refrigerant to increase its temperature and pressure. This refrigerant then dissipates heat through the condenser, reduces pressure through the electronic expansion valve, and absorbs heat in the evaporator, thus cooling the air in the passenger compartment. When the battery pack requires cooling, the EAC, also under VCU control, adjusts the cooling capacity to cool the battery coolant through the battery cooler, meeting the battery's cooling needs. When both the passenger compartment and battery pack require cooling simultaneously, the EAC's rotational speed is controlled based on whether charging is in progress and the priority of the cooling needs of each component.

[0092] First and Second Electronic Water Pumps: The first electronic water pump provides the necessary water flow for the cooling circulation of components such as the motor, electronic control system, and DC-DC converter. Its speed is adjusted via PWM control, thereby controlling the coolant flow and circulation speed. Based on the temperature of these components, the VCU controls the on / off state and speed of the first electronic water pump to ensure sufficient cooling capacity under different operating conditions. When the motor temperature is ≥45℃, the first electronic water pump turns on and operates at the corresponding speed for cooling. The second electronic water pump provides power to the battery cooling circulation loop, also using PWM control. In battery pack thermal management, when the BMS determines that the battery temperature and charge have reached thresholds, it sends a cooling, temperature equalization, or heating request, and the second electronic water pump turns on. In constant speed control mode, after meeting the activation conditions, the pump duty cycle is controlled at 86%. After the vehicle is powered off or charging is completed, if the temperature difference and SOC meet the conditions, it will continue to operate for temperature equalization control.

[0093] Cooling Fan: Provides the necessary airflow for cooling the front-end cooling module. Its operation is controlled by the VCU based on the temperature requirements of different components and the status of the air conditioning system. In the air conditioning system, the VCU controls the high and low speed operation of the cooling fan according to the enable status of the electric air conditioning compressor and the state of the three-state pressure switch. When the electric air conditioning compressor is enabled and the air conditioning medium-pressure switch is open, the low-speed fan is activated; when the electric air conditioning compressor is enabled and the air conditioning medium-pressure switch is closed, the high-speed fan is activated. When cooling components such as the MCU and DC-DC converter, the VCU calculates the cooling fan speed requirements for each component and controls the fan operation according to the maximum requirement. When the vehicle is powered off, if the temperature of the relevant components exceeds the set value, the cooling fan is delayed and shut down.

[0094] Electronic Expansion Valve (EXV) and Shut-off Valve (SOV): The electronic expansion valve is the expansion valve before the battery cooler, which throttles and expands the refrigerant in the battery cooling circuit to reduce its temperature. The VCU obtains the initial opening degree of the EXV from a table based on the cooling power request from the BMS, and then adjusts it autonomously according to the superheat. When the superheat is <3℃, the valve opening decreases by 10 steps every 10 seconds, eventually not less than 50 steps; when the superheat is >10℃, the valve opening increases by 10 steps every 10 seconds, and the upper limit of the opening is limited according to the operating conditions. Under discharge conditions, when there is a need for air conditioning in the passenger compartment, the EXV opening degree must not exceed 15%. The shut-off valve is a solenoid valve before the HVAC system, used to cut off the refrigerant circulation of the passenger compartment air conditioning system. It is a normally open valve; a low level indicates it is open, and a high level indicates it is closed. The VCU controls the opening and closing of the shut-off valve according to the vehicle status, air conditioning cooling demand, and battery cooling demand. Before closing the shut-off valve, it needs to determine whether there is a demand for the electronic expansion valve to avoid both closing simultaneously, which could cause the electric air conditioning compressor to explode.

[0095] The second heater plays a crucial role in the battery pack thermal management system – liquid heating – by providing heat to the water circuit to heat the battery. During fast charging and discharging heating, it operates based on control signals from the BMS and VCU. It initially operates at its rated power of 5kW, adjusting the heating power output to maintain the battery inlet water temperature at 50°C once the outlet temperature reaches 50°C. Simultaneously, the second heater provides feedback on its operating status, power consumption, and fault level. The first heater, on the other hand, is used for passenger compartment heating. It activates when the vehicle is in the ON position and under high voltage, a PTC activation request is received, the passenger compartment PTC relay is fault-free, and the blower is on, providing heat to the passenger compartment.

[0096] Notes: T1: Maximum battery pack temperature; T1': Minimum battery pack temperature; T2: Battery pack inlet temperature; T2': Battery pack outlet temperature; Tmean: Average battery pack temperature.

[0097] The electric vehicle thermal management system with the above structure has the following advantages: (a) Energy consumption is significantly reduced; The electric vehicle thermal management strategy of this invention significantly reduces the energy consumption of the thermal management system. In high-temperature summer environments, the average energy consumption of the air conditioning system is reduced by approximately 20%; in low-temperature winter environments, the energy consumption of the heating system is reduced by approximately 15%. This not only extends the vehicle's driving range but also reduces user operating costs.

[0098] (ii) Temperature control accuracy has been greatly improved; The temperature fluctuation range inside the vehicle has been significantly reduced, maintaining the temperature in the driver's cabin within a comfortable range and improving passenger comfort. Temperature control for critical components such as the battery and motor is more precise, effectively preventing performance degradation and shortened lifespan caused by excessively high or low temperatures. Testing showed that the battery's operating temperature fluctuation range has decreased from ±5℃ to ±2℃, and the motor's operating temperature fluctuation range has decreased from ±8℃ to ±3℃.

[0099] Secondly, embodiments of the present invention also provide a vehicle including an electric vehicle thermal management system with the above-described structure. The vehicle is an electric vehicle, and this electric vehicle thermal management system can be referred to... Figures 1 to 6 Further details will not be elaborated here. Since the vehicle of the present invention includes the electric vehicle thermal management system described in the above embodiments, it possesses all the advantages of the aforementioned electric vehicle thermal management system.

[0100] 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 non-substantial improvements made using 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. An electric vehicle thermal management system, characterized in that, It includes a vehicle control unit, a battery management system, a three-in-one module, an electric air conditioning compressor, a first heater, a second heater, a first electronic water pump, a second electronic water pump, and a cooling fan. The first heater is arranged opposite to the evaporator, the second heater is located between the second electronic water pump and the power battery, and the first electronic water pump is connected to the drive motor. The vehicle control unit interacts with the battery management system, the three-in-one module, the electric air conditioning compressor, and each actuator through a communication network. Based on the vehicle's operating status, battery pack temperature, motor temperature, motor controller temperature, DC-DC temperature, and passenger compartment requirements, it controls the start / stop and operating power of the first electronic water pump, the second electronic water pump, the cooling fan, the electric air conditioning compressor, the first heater, and the second heater.

2. The electric vehicle thermal management system according to claim 1, characterized in that, The vehicle control unit controls the activation of the first electronic water pump based on the motor temperature, motor controller temperature, and DC-DC temperature. The first electronic water pump is activated when any of the above temperatures is ≥45℃, and deactivated when any of the above temperatures is ≤40℃. The unit also adjusts the duty cycle of the first electronic water pump according to the gear and vehicle speed.

3. The electric vehicle thermal management system according to claim 1, characterized in that, When the vehicle is charging or under high voltage, the battery management system determines whether the battery pack temperature has reached the cooling threshold. When the cooling or temperature equalization request is met, it sends a cooling request, a temperature equalization request, and target water temperature information to the vehicle control unit. The vehicle control unit responds to the request by controlling the opening status of the second electronic water pump, the shut-off valve, and the electronic expansion valve, and adjusting the speed of the electric air conditioning compressor to achieve cooling or temperature equalization control of the power battery.

4. The electric vehicle thermal management system according to any one of claims 1 to 3, characterized in that, The second electronic water pump operates using PWM control. When the activation conditions are met, its duty cycle is 86%. After the vehicle is powered off or charging is completed, if the difference between the highest temperature T1 and the lowest temperature T1' of the power battery is greater than 11°C and the SOC is greater than 5%, the second electronic water pump will remain on to perform temperature equalization control until the difference between the highest temperature T1 and the lowest temperature T1' of the power battery is less than or equal to 8°C or the second electronic water pump runs for 60 minutes and then shuts off.

5. The electric vehicle thermal management system according to any one of claims 1 to 3, characterized in that, The electric air conditioning compressor is located in the refrigerant circulation loop, which includes an electronic expansion valve, a condenser, and a battery cooler. The electronic expansion valve is located between the outlet of the condenser and the inlet of the battery cooler and is connected to both the condenser and the battery cooler. The battery cooler is connected to the power battery and the second electronic water pump. The electric air conditioning compressor is located between the inlet of the condenser and the outlet of the battery cooler and is connected to both the condenser and the battery cooler. The electronic expansion valve determines its initial opening degree by looking up a table based on the cooling power request from the battery management system, and then performs closed-loop adjustment based on the superheat ΔT. When ΔT < 3℃, the valve opening is reduced by 10 steps every 10 seconds, but not less than 50 steps. When ΔT > 10℃, the valve opening increases by 10 steps every 10 seconds and is limited by the upper limit of the opening.

6. The electric vehicle thermal management system according to claim 5, characterized in that, The condenser is connected to the shut-off valve, which is connected to the thermostatic expansion valve, which is connected to the evaporator. The shut-off valve is a normally open solenoid valve. When the vehicle is under high pressure and there is a need for both battery cooling and passenger compartment cooling, the shut-off valve closes if the evaporator temperature is <1℃ or the battery pack maximum temperature is ≥55℃. The shut-off valve reopens when the evaporator temperature is ≥4℃ or the battery pack temperature is ≤53℃.

7. The electric vehicle thermal management system according to any one of claims 1 to 3, characterized in that, The shut-off valve is opened and closed based on vehicle status, air conditioning system, and power battery cooling requirements: ① When the vehicle is in the OFF position and enters the charging process, the VCU receives a cooling request from the BMS; ② After the vehicle is connected to high voltage, if there is a simultaneous need for battery cooling and cab cooling, the shut-off valve will close when the evaporator temperature is <1℃. The shut-off valve will reopen when the evaporator temperature is ≥4℃.

8. The electric vehicle thermal management system according to any one of claims 1 to 3, characterized in that, When the battery management system detects that the minimum temperature of the power battery T1' ≤ 5℃ and Tmean ≤ 16℃ and SOC ≥ 30%, the battery management system sends a thermal management heating request to the vehicle control unit. After the vehicle control unit controls the second electronic water pump to turn on, it sends an enable signal for the second heater after a 3-second delay, so that the second heater works at the rated power of 5kW until the outlet water temperature reaches 50℃, and then adjusts the heating power to maintain the temperature.

9. The electric vehicle thermal management system according to any one of claims 1 to 3, characterized in that, In charging conditions where both the passenger compartment and the power battery require cooling, the cooling of the power battery is the primary method, while the cooling of the passenger compartment is secondary. The maximum speed of the electric air conditioning compressor is set to 6000 rpm. When not charging, the system primarily cools the passenger compartment, with the electric air conditioning compressor set to a maximum speed of 4000 rpm.

10. A vehicle, characterized in that, The electric vehicle thermal management system includes any one of claims 1 to 9.

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