The rapid development of the automobile market, is bound to drive the development of related industries. Automotive air conditioning as a car must have the comfort function, but also encountered unprecedented opportunities for development. Automotive air conditioning system Sensor is to achieve the air inside the compartment for refrigeration, heating, ventilation and air purification of comfort equipment. It can provide a comfortable ride for the car environment, reduce the driver's fatigue strength, improve traffic safety. Air conditioning devices have become a measure of whether the car function is perfect.

  Car air conditioning is the most basic and complex car refrigeration system. The compressor power of a modern on-board refrigeration system is driven by a motor. The refrigeration system consists of a compressor, a condenser, a liquid drier, an expansion valve, an evaporator and a blower. Car cooling system components between the use of copper (or aluminum) and high pressure rubber tube connected into Pressure Sensor a closed system. When the refrigeration system is in operation, the refrigerant circulates in this closed system in two types of compressed and expanded conditions.

(1) Compression process: the compressor inhalation of the evaporator at the exit of the low temperature and low pressure refrigerant gas, it is compressed into high temperature and high pressure gas exclusion compressor.
(2) heat process: high temperature and high pressure superheated refrigerant gas into the condenser, due to the pressure and temperature reduction, refrigerant gas condensed into liquid, and discharge a lot of heat.
(3) throttling process: the temperature and pressure of the refrigerant liquid through the expansion device after the larger volume, pressure and temperature dropped sharply to mist (small droplets) discharge expansion device.
(4) endothermic process: mist refrigerant liquid into the evaporator, so the refrigerant boiling point is much lower than the evaporator temperature, so the refrigerant liquid evaporated into gas. In the evaporation process a large number of absorption of heat around, and then low-temperature low-pressure refrigerant vapor into the compressor.
   
  Automotive air-conditioning technology continues to develop, the compressor evaporator technology is also continuous progress, and with the energy-saving environmental protection is getting higher and higher, because the car is a DC power supply system, so the inverter should be able to directly use DC power supply. If the inverter power supply is too high or too low will cause a fault alarm, and the car's power supply system voltage is generally low, so in order to make the system can work properly, designed for automotive air conditioning inverter dedicated low voltage alarm level Will be lower than the standard inverter. When the air conditioning system is working, first check the voltage of the voltage system to determine whether it is within the normal working range. After the normal start, the inverter will detect the DCBUS value, and then calculate Speed Sensor the value of the DCBUS according to the set V / F curve. Output frequency, control according to the air conditioning controller set the temperature value converted to the control PLC, PLC and then converted to 0 ~ 10V analog signal sent to the inverter AVI, the frequency of the inverter command source, frequency Compare the size of the two frequency command values ​​and then output them according to the smaller frequency command.