The Research On PMSM Compressor Control System For Air-Conditioner

With the growing prevalence of the home-used air-conditioner, more power is consumed by the air-conditioner; it has become more important to manufacture energy-saving air-conditioner. PMSM (Permanent Magnetic Synchronous Motor) compressor is the most effective and advanced one among the various energy-saving technologies, therefore, it has been a key and hot research topic on driving the sensorless PMSM compressor.Many papers have studied on sensorless PMSM and BLDCM (Brushless DC Motor) control system, but few can meet the home-used air-conditioner's requirement. Although many PMSM inverter air-conditioners are sold on the market, the key techniques about the control system are not opened as patents or confidential data.This paper studies several rotor position detecting method used in the sensorless IPMSM, combining the characteristic of the air-conditioner PMSM compressor, it proposes a discrete and a continuous detecting position method respectively and apply them in the air-conditioner PMSM compressor control system. It designs a load torque observer and torque compensation algorithm to reduce the vibration on the one piston rotary compressor system. It also develops two PMSM compressor controllers based on the square wave driving mode and sine wave driving mode respectively. The key point about this thesis is as follow:It presents the advantages and disadvantages on two types of direct BEMF position method through analysis, simulation and experiment and proposes a novel rotor position detecting method based on the compressor's line voltage which has a less position error and easy to compensate, be insensitive to carrier frequency and can be used in various PWM modulation modes. The position error is compensated in the square wave control system which produced by the reaction of the IPMSM salient pole.This thesis designs a rectangle wave control system based on the compressor line voltage position detector. The compressor noise that is related to the PWM modulation mode is studied in detail, and it concludes that the PWM-ON mode is the best one to reduce the noise, which is proved by simulation and experiments. In this control system, compressor's low speed vibration is improved through a simple torque compensation method. A novel wide-angle driving method is proposed to reduce the torque ripple and noise.A novel SMO (Sliding Mode Obsever) mathematical model for IPMSM is given based on "i_d=0", simulation and experiment proves that it can be used in the compressor control system, if the salient pole rate and BEMF is not too high. It also proposes the other rotor position observer based on PLL and BEMF states observer on the hypothesis frame of axes, PLL can diminish the error to zero between the hypothesis frame and the actual frame, and position accuracy is improved through the extended BEMF model.A PMSM compressor vector control system is implemented based on the PLL (Phase-locked Loop) rotor position observer; it has a higher efficiency using MTPA (Maximum Torque Per Ampare) control strategy and can be running at a very high speed by weakening the rotor flux. Load torque is compensated at low speed for one piston rotary compressor in 2hp (horsepower) PMSM compressor control system.This thesis have developed a square wave compressor controller and a sine wave compressor controller respectively, which are sold in the market with large batch size; it also designed a partial switching PFC to control the input harmonic current below the IEC standard; In the last, it presents a simple method to obtain the PMSM compressor electrical parameter and design the mainly control parameter of the controller.