Research On Hybrid Sensorless Control Strategy For Surface-mounted Permanent Magnet Synchronous Motor

The real-time position of the rotor is required in field oriented control(FOC)of permanent magnet synchronous motor(PMSM).Position sensors with high precision are usually quite expensive,and there are some common problems these position sensors might have,such as increasing the size of the motor and the complexity of the hardware.This is among the reasons why sensorless technology has been widely studied by both domestic and foreign researchers.Aiming at a surface-mounted permanent magnet synchronous motor(SPMSM),the pulsating high frequency signal injection method used in the start-up and low-speed operation and the sliding mode observer(SMO)used in the middle-speed and high-speed operation in the sensorless control of the motor are studied in this paper.Both of the methods are optimized to some degree,and hysteresis switch is applied for the hybrid sensorless control of the SPMSM.In the start-up and low-speed area,firstly,the principle of the pulsating high frequency signal injection method and the resistance’s influence on the position estimation system are analyzed in detail.Then,aiming at the high-frequency components in the feedback path of the current loop,two methods,moving average filter(MAF)and delayed signal cancellation(DSC),which can eliminate harmonics of specific frequency are compared.According to the filtering characteristics of them,the MAF is selected to be the filter of the current loop,and this filter can completely remove the high frequency components in the feedback path of the current loop in theory.In the middle-speed and high-speed area,firstly,the traditional SMO is constructed,then the resistance and inductance’s influence on the position estimation system and the stability of SMO are analyzed.After that,aiming at the chattering problem of the traditional SMO,several methods are adopted.First,the “sgn”function in the SMO is replaced by the smoother “sigmoid” function.Then,the estimated back electromotive force(EMF)is optimized by a model reference adaptive system(MRAS).Finally,the quadrature phase-locked loop(QPLL)is optimized and its anti-interference ability in high-speed area is enhanced.Based on theoretical and simulation analysis,a motor controller based on TMS320F28355 is designed,and a hardware control platform of PMSM is built.Feasibility of the two sensorless control methods and effectiveness of the optimization algorithms are verified by experiment.