Study On The Control System Of Vary-Frequency Air Conditioner

With the arrival of the energy source crisis worldwide, governments in many countries have been promoting the energy saving techniques positively. As the main energy consuming equipment in family, traditional air conditioners are withdrawing from the market gradually because of its low efficiency. Thanks to the advantages of high efficiency, energy saving and more comfort, new generations of the variable frequency air conditioner have become the developing trend from now on. The manufacturing technique of the variable frequency air conditioner in our country, started from early 1990's, is still immature up to now. Combining the advanced technology in this field, the author has designed an intelligent variable frequency air conditioner controller.Variable frequency air conditioner is the future of household air condition. Permanent magnet brushless DC compressor has found wide applications due to their high efficiency and the convenient way of control. Generally speaking, the drive of brushless DC motor requires a position sensor to offer proper commutation to the controller. The application of completely sealed compressor can not adopt to the sensor because of its low reliability at high temperature. The technique of sensorless drive for brushless DC motor is now receiving public attention.This paper makes a comprehensive view of the rising, development and present situation of control technique for brushless DC motor, and application foreground of brushless DC motor on household air-condition is introduced. Configuration and principium of brushless DC motor are briefly explained.Fuzzy control techniques have certain amounts of applications in air conditioner control recently. Their fuzzy rule bases, which are the key sections of the fuzzy controller, have been decided by expert experiences in advance. Most of them could not be regulated during the process, easily causing the problem of controlled parameters over regulating and fluctuating. According to the air conditioners' working characteristics, a novel fuzzy controller, named adaptive rules continuously correct fuzzy controller is designed in this paper. The experiments have proved that this fuzzy controller has the advantages of fast response rate, low overshoot and good stability.A specially designed digital signal processor (DSP) for motion control has been chosen in this paper. Its powerful functions provide the best development platform for air conditioner controller. Using DSP chip as the core of the control system, this paper applied voltage modulation (PWM) for the continuous control of compressor. Using the intelligent power module (IPM) has improved the performance of the system, especially for the reliability characteristics. Software and hardware's design of the system based on TMS320C241 are briefly introduced. The reliable protection of the system and the control of sensorless brushless DC compressor and brushless DC fan motor are realized. At the same time, the deterioration of the controller brought by brushless DC motor reversing to generate electricity in starting process has been resolved.Software design work mainly includes programs for indoors unit control, outdoors unit control and communications between these control. This paper has provided the flow diagrams of the main programs.