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What is the principle of air conditioning and heating in pure electric vehicles

At present, there are two types of air conditioning and heating systems for pure electric vehicles: PTC thermistor heaters and heat pump systems. The working principles of different types of heating systems vary greatly.

The PTC used in pure electric vehicles is a semiconductor thermistor. Due to the characteristics of simple structure, low cost, and fast heating, PTC heaters have been widely used in pure electric vehicles (especially low-end models). Of course, there are exceptions. The NIO ES8, which is positioned as a mid-to-high end, still uses a PTC air heater system and is equipped with two PTC heaters.

PTC coolant heater
PTC coolant heater1
PTC coolant heater
20KW PTC heater

The function of a heat pump is to transfer heat energy from a low-temperature heat source to a high-temperature heat source. Its working principle is similar to that of an air-conditioning refrigeration system, except that the direction of heat transfer is just opposite. When the air conditioner cools, it transfers the heat from the indoors to the outdoors, while the heat pump heating system transfers the heat from the outside of the car to the inside of the car. The heat pump heating system is generally integrated with the air conditioning and refrigeration system, and the heat transfer path is controlled through the valve. In addition, when heating, the preheating of the power battery cooling system can be effectively used. In this respect, it is similar to the heating system of a traditional car. Therefore, compared with the PTC heater, the thermal efficiency of the heat pump system is higher, the energy consumption is lower, and the impact on the cruising range is relatively small. But the disadvantages are also obvious: complex structure, high cost, slow heating speed, especially under low temperature conditions, the heating effect is poor.

Based on the above, in some mid-to-high-end pure electric vehicles, in order to ensure the temperature in the cabin, a hybrid mode of heat pump + PTC coolant heater is often used. In the initial stage, when the temperature of the power battery cooling system is low, the PTC heater is turned on first, and the heat pump heating system is started after the temperature of the coolant rises.

The original intention of plug-in hybrid electric vehicles is to be able to use without oil. The daily commuting is still based on pure electric mode. Can't drive, it can use PTC, heat pump or plus pulse heating. At present, hybrid vehicles such as DM-i mainly use PTC for heating. The heating principle is very simple, which is simply "electric heating".

PTC air heater02
PTC heater

Post time: Mar-10-2023