Structure, circuit, electronic control, control system and working principle of electric vehicle air conditioning system
1. Structural composition of the air conditioning system of new energy pure electric vehicles
The air conditioning system of new energy pure electric vehicles is basically the same as that of traditional fuel vehicles, consisting of compressors, condensers, evaporators, cooling fans, blowers, expansion valves and high and low pressure pipeline accessories. The difference is that the core parts of the new energy pure electric vehicle air conditioning system used to work - the compressor does not have the power source of the traditional fuel vehicle, so it can only be driven by the power battery of the electric vehicle itself, which requires the addition of a drive motor in the compressor, the combination of the drive motor and the compressor and the controller, that is, we often say - electric scroll compressor
2. Control principle of new energy pure electric vehicle air conditioning system
The whole vehicle controller ∨CU collects the AC switch signal of air conditioner, pressure switch signal of air conditioner, evaporator temperature signal, wind speed signal and ambient temperature signal, and then forms the control signal through the CAN bus and transmits it to the air conditioner controller. Then the air conditioner controller controls the on-off of the high voltage circuit of the air conditioner compressor.
3. Working principle of new energy pure electric vehicle air conditioning system
New energy electric air conditioning compressor is the power source of new energy pure electric vehicle air conditioning system, here we separate the refrigeration and heating of new energy air conditioning:
(1) The refrigeration working principle of the air conditioning system of new energy pure electric vehicles
When the air conditioning system works, the electric air conditioning compressor makes the refrigerant circulate normally in the refrigeration system, the electric air conditioning compressor continuously compresses the refrigerant and transmits the refrigerant to the evaporation box, the refrigerant absorbs heat in the evaporation box and expands, so that the evaporation box is cooled, so the wind blown by the blower is cold air.
(2) The heating principle of the air conditioning system of new energy pure electric vehicles
The air-conditioning heating of the traditional fuel vehicle relies on the high temperature coolant in the engine, after opening the warm air, the high temperature coolant in the engine will flow through the warm air tank, and the wind from the blower will also pass through the warm air tank, so that the air outlet of the air conditioner can blow out the warm air, but the electric vehicle air conditioning because there is no engine, At present, most of the new energy vehicles on the market achieve new energy vehicle heating by heat pump or PTC heating.
(3) The working principle of the heat pump is as follows: in the above process, the low-boiling liquid (such as the freon in the air conditioner) evaporates after decompression by the throttle valve, absorbs heat from a lower temperature (such as outside the car), and then compresses the steam by the compressor, making the temperature rise, releases the absorbed heat through the condenser and liquefied, and then returns to the throttle. This cycle continuously transfers heat from the cooler to the warmer (heat needed) area. Heat pump technology can use 1 joule of energy and move more than 1 joule (or even 2 joules) of energy from colder places, resulting in significant savings in power consumption.
(4) PTC is an abbreviation of Positive Temperature Coefficient (positive temperature coefficient), which generally refers to semiconductor materials or components with a large positive temperature coefficient. By charging the thermistor, the resistance heats up to raise the temperature. PTC, in the extreme case, can only achieve 100% energy conversion. It takes 1 joule of energy to produce at most 1 joule of heat. The electric iron and curling iron used in our daily life are all based on this principle. However, the main problem of PTC heating is power consumption, which affects the driving range of electric vehicles. Taking a 2KW PTC as an example, working at full power for an hour consumes 2kWh of electricity. If a car travels 100 kilometers and consumes 15kWh, 2kWh will lose 13 kilometers of driving range. Many northern car owners complain that the range of electric vehicles has shrunk too much, partly because of the power consumption of PTC heating. In addition, in the cold weather in winter, the material activity in the power battery decreases, the discharge efficiency is not high, and the mileage will be discounted.
The difference between PTC heating and heat pump heating for new energy vehicle air conditioning is that: PTC heating = manufacturing heat, heat pump heating = handling heat.
