Vehicle Thermal Management System Case
1 Thermal management system architecture
The thermal management system architecture of a certain pure electric vehicle is shown in Figure 1. This thermal management system uses a heat pump air conditioner to organically integrate direct cooling and heating of the battery, cooling of the electric drive system, and cooling and heating of the passenger compartment. In the electric drive circuit, a separate water cooling circuit is set up, which is connected to the heat pump system through a plate heat exchanger for heat transfer, which can realize waste heat recovery and stall heating functions; in cold winter, in order to solve the problem of poor heating effect of heat pump air conditioners, matching PTC to increase the heating effect of the passenger compartment. The thermal management system enables cooling and heating needs in multiple modes.
2 Principle of thermal management system
Because the system has multiple working modes, this article only introduces the working principle of cooling and heating modes where the battery or passenger compartment needs to be cooled.
1) Principle of power battery cooling. When the power battery temperature is high and needs to be cooled, the air conditioning and refrigeration solenoid valve, air heat exchange solenoid valve, battery electronic expansion valve and battery cooling solenoid valve in the system are opened (the battery heating solenoid valve is closed), and when the refrigerant flows through the battery electronic expansion valve , after throttling and expansion, it evaporates and absorbs heat in the battery pack plate heat exchanger, taking the heat away to achieve the purpose of battery cooling. If the passenger compartment also needs cooling at this time, you only need to open the refrigeration electronic expansion valve (the air conditioning and heating solenoid valve is closed), and part of the refrigerant will evaporate and absorb heat in the evaporator in the car to achieve cooling of the passenger compartment.
2) Principle of power battery heating. When the battery temperature is low and needs to be heated, the battery heating solenoid valve, battery electronic expansion valve, water source heat exchange solenoid valve, and air conditioning heating solenoid valve in the system open (heating electronic expansion valve, air conditioning and refrigeration solenoid valve, air heat exchange solenoid valve, The refrigeration electronic expansion valve is closed), and the high-temperature refrigerant compressed by the compressor flows through the battery pack plate heat exchanger to heat the low-temperature battery. After heating, the refrigerant temperature decreases, flows through the plate heat exchanger, absorbs the heat of the electric drive circuit, and realizes waste heat recovery. If the passenger compartment also needs heating at this time, you only need to open the heating electronic expansion valve, and part of the high-temperature refrigerant flows through the condenser in the car to release heat to the passenger compartment, and then merges with the battery heating refrigerant in front of the plate heat exchanger to continue participating in the cycle. . If the ambient temperature is very low, the system turns on the PTC auxiliary passenger compartment heating.
