Compressor air conditioners transfer heat from the enclosed space to the outside, or bring heat from the outside into the enclosed space. No heat is generated during the process, but only heat transfer.

Compressor air conditioners transfer heat from the enclosed space to the outside, or bring heat from the outside into the enclosed space. No heat is generated during the process, but only heat transfer. The compressor air conditioner on an electric vehicle is logically managed by the vehicle controller VCU, and its specific implementation forms are various. Here, only a typical form is used to explain its detailed working process. 1 Electrical working process From an electrical point of view, the compressor air conditioner is mainly composed of the following parts: air conditioner controller, compressor and thermodynamic system, compressor motor and its controller, communication module, temperature and pressure sensor. As shown below. The electrical of the vehicle air conditioner is divided into two parts, the high voltage part and the low voltage part. As shown in the figure below, DC+ and DC- are high-voltage power supplies that are directly connected to the compressor motor controller. The "air conditioning relay" in the figure is the power switch of the air conditioning controller. Logic The low-voltage part of the air conditioner is controlled by the VCU. The VCU controls the switching of the entire air conditioner by controlling the 12V power circuit "air conditioner relay"; transmits the command information to the air conditioner controller through the CAN bus and sets the target value of the operating temperature; the air conditioner controller feeds back the air conditioning work to the VCU Status information, including on/off information of the strong current circuit switch, compressor pressure, compressor inlet and outlet temperatures. The high-voltage power supply of the air-conditioning compressor comes from the on-board DCDC converter. The air-conditioning controller controls the opening and closing of the contactor on the power circuit through the contactor trigger port, and then controls the working state of the compressor motor. The compressor is integrated with the motor and motor controller that power it, and the space is relatively small. The electromagnetic interference in the space is often the cause of the misoperation of the controlled motor. Compressor motors generally use permanent magnet synchronous motors or permanent magnet DC brushless motors. No other reason, small size and simple control. The motor speed can be adjusted in a wide range as required. Turn the ignition switch of the electric vehicle to the "ON" position. If the "A/C" switch of the air conditioner is turned on at this time, the air conditioner can start to work. Adjustment of cooling capacity The air conditioner controller closes the high-voltage loop contactor, and the compressor enters the working state. Passengers adjust the air temperature in the car by adjusting the air volume and temperature setting buttons. The larger the air volume, the more heat is brought into the vehicle cabin from the condenser, and the greater the power of the compressor is required. The greater the gap between the set temperature and the current temperature, the greater the compressor power required. The air conditioning controller achieves the purpose of controlling the cooling and heating capacity by controlling the motor speed of the electric compressor. When the motor speed is high, the corresponding operating speed of the compressor increases, the refrigerant flow rate increases, and the cooling capacity increases. 2 Physical working process From a physical point of view, the four essential components of air conditioning include: evaporator, condenser, compressor and expansion valve. Four-way solenoid valve is a change-over switch for switching between cooling mode and heating mode. The cooling mode can be seen as that the air conditioning system places the evaporator in the vehicle interior to allow the refrigerant to evaporate and absorb heat, taking away the heat in the room; the heat is taken to the outside through the circulation pipe, and this part of the heat is condensed and released by the condenser Way, released into the outdoor air. The refrigerant absorbs heat from the room and turns into a room-temperature and low-pressure gas; after being boosted by the compressor, it becomes a high-temperature and high-pressure gas, flows into an outdoor condenser (the outdoor heat exchanger in the car), undergoes a heat release process, and the gas condenses into a liquid; , Flows into the expansion valve, part of the vaporization absorbs heat, and the refrigerant turns into low-temperature and low-pressure wet steam; the wet vapor enters the evaporator in the vehicle interior, further vaporizes and absorbs heat, forms room temperature gas, and returns to the compressor. Heating is the reverse process of cooling. In a two-way heat pump, it is realized by reversing the solenoid valve. What we see is equivalent to putting the condenser in the vehicle interior and the evaporator outdoors. However, in practical applications, the compression mechanism is rarely used alone. Instead, it uses other heating equipment to provide the heat source, and then uses the air conditioning system to make the heat flow evenly into the vehicle interior. For example, use PTC electric heating, or use the cooling water heating of the motor controller. The heating capacity of vehicle-mounted compressor air conditioners needs to be further improved.

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