| Compressor is the core component of an air conditioner. The compressor of traditional fixed-speed air conditioner use a switch control method, which has the disadvantages of power loss, temperature fluctuations and large noise, and the compressor can be damaged probably. With the frequency control technology being used in air conditioners, the times of start and close of the compressor is reduced, the fluctuation of the inner temperature become less, and people in the room feel more comfortable. The air conditioning effection is well and the goal of saving energy is achieved.The thesis designed and implemented a vary-frequency control system for a kind of new household air conditioner. It introduced the the overall structure and working process of the household air conditioner firstly. Designed the overall structure of the control system.Through the analysis to the mathematical model of the motor of the compressor and the output configuration of voltage vector of the voltage inverter, the thesis proposed a magnetic field orientation vector control method.The method controlled excitation current and torque current by controlling the location and the size of stator current vector in rotating coordinate system, it implemented the decoupling control to the magnetic field and torque just like the DC motor. And it simulated magnetic field orientation control method of the compressor, which got the expected results. After studying the svpwm method, the thesis proposed a V/F control method based on SVPWM modulation technology for the compressor which had been used in the actual system.The hardware circuit includes the main controlling circuit, the power supply module and the display module, etc. And the debugging operation of this circuit is successfully operated. The hardware circuit uses st7MCU made by STMicroelectronics and is cost-effective as its core processor. The software of frequency conversion air conditioning main control program and frequency conversion air conditioning compressor driving control system is designed and debugged. The software programs include the program of main technological process, the program of frequency conversion driving controlling, the program of space vector modulation, signal sampling control procedures electronic expansion valves control procedures, program of display, the program of communications, the program of system protection and the fault processor.With the results of the the experiment debugging of the real vary-frequency air conditioner control system:the vary-frequency air conditioner control system designed in this thesis meets the expected performances, the precision and the efficiency of the temperature control has been improved with the introduction of the control system, this variable frequency drive system can change the frequency and the speed of the motor very well when taking the load of the experiment, the voltage output meets the conclusion of the theory analysis, the voltage output is Three-phase symmetric sine wave, meets the requirements of the control, without concussion basicly, the performances of the temperature control of the household air conditioner have been improved greatly,and meet the original design requirements. |
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