Why Electric Vehicles Need Thermal Management
The thermal management system of automobiles is an important system for regulating the cabin environment and working environment of automotive components. It comprehensively improves energy utilization efficiency through refrigeration, heating, and internal heat conduction. The thermal management system of electric vehicles is more complex than that of regular fuel vehicles, due to the fact that pure electric vehicles have more components that require thermal control, such as batteries, controllers, and electric motors. The thermal management system of pure electric vehicles not only includes the air conditioning system, but also adds different parts such as battery pack environment, power electronic devices, and motor heat dissipation according to the thermal management requirements.
Heating:
In winter, drivers and passengers need warmth inside the car, which involves the heating needs of the thermal management system. Batteries are bulky and heavy in electric vehicles. To warm up from a low-temperature environment to a suitable temperature, it is necessary to consider both the heating speed that the battery can withstand and the stable heating power output of the thermal management system. These all require high requirements for the thermal management system. For example, the design of the heat exchange circuit inside the battery, the heat exchange design between the battery and the external heating circuit, the design of the cabin heat exchanger and heating circuit, the preheating strategy of the battery, and the control strategy for adjusting the corresponding user temperature in the cabin, etc.
Battery Cooling:
Due to the existence of internal resistance and discharge balance circuits, the current flowing through the battery during charging and discharging will cause the battery to generate heat, which poses a challenge to the battery; The temperature rise of the battery also varies depending on different cars and batteries. For example, some micro cars or small cars have low charging and discharging power, and the continuous temperature rise of the battery is not too large. In this case, some air cooling methods or smaller water cooling cooling circuits can be used; Some electric models of SUVs and luxury cars require strong battery cooling capacity to meet the needs of high-power charging and driving.
High power electronic cooling:
In addition to the battery, there are also electric motors and electronic controls. In fact, there are also on-board chargers such as OBC (On Board Charger), high-voltage to low-voltage DC/DC, and high-voltage distribution boxes in the car that also require heat dissipation. Because the power electronics in these power devices are relatively the same, but their power sizes are different and their internal designs are different. For example, electronic control, vehicle charger and DC/DC all use IGBT insulated gate bipolar junction transistor. Its heating power is related to the switching speed, and its switching speed also directly affects the output power of these power electronics.
The thermal management system of electric vehicles assists in driving by maximizing the utilization of battery energy. By carefully reusing the heat energy in the vehicle to the air conditioning and batteries inside the vehicle, thermal management can save battery energy and extend the vehicle's driving range, with its advantages particularly significant in extreme cold and hot temperatures. The thermal management system of electric vehicles mainly includes high-voltage battery management system (BMS), battery cooling plate, battery cooler, high-voltage PTC electric heater, and heat pump system according to different vehicle models.
