| With the promotion of permanent motor and the improvement of the energy-saving air-conditioner,permanent magnet synchronous motor(PMSM)is widely used as driven motor of the air-conditioner compressor in place of the induction motor owing to its advantages such as good speed regulation performance,high efficiency,high power density and compact structure.Aiming at the specific research subject,that is the air-conditioner compressor,the sensorless PMSM compressor and the method of speed ripple suppression are studied in this paper.Firstly,according to the simplified PMSM model,mathematical models under different coordinate systems are derived.Then the different current control strategies of vector control method are introduced and MTPA is used.Also,SVPWM is analyzed and adopted to improve the utilization of DC supply voltage.Secondly,sensors cannot be installed inside a compressor because of the limited space and high temperature.Thus,position sensorless control technique is necessary.I/F control is used for the PMSM low-speed operation,and Luenberger state observer with the phase locked loop(PLL)is used to estimate the rotor position for the medium and high speed range.The parameter tuning method is proposed in details.Simulation verified the algorithms above.Thirdly,the load principle of the air-conditioner compressor is theoretically derived and a method of speed ripple suppression via torque current feedforward compensation is proposed.Since the sine feedforward current need accurate phase to get speed ripple well suppressed,the proposed method obtains the optimal compensation phase based on dichotomy.And the digital implementation of the proposed method is given.Finally,an experimental platform including both hardware and software system for the air-conditioner compressor is introduced in details.Then,the position sensorless algorithm and the proposed method for speed ripple suppression are verified by experimental results. |
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