Variable structure MRAS for PMSM sensorless control

ZHOU Jiahua1, JIA Hongping1, ZHANG Peng1, HU Yazhe

(1.School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China;
2.School of Electrical Engineering, China University of Mining and Technology, Xuzhou 221000, China)

Abstract: Aiming at the problem of system shock and inaccurate estimating speed in a lowspeed PMSM sensorless control, the model reference adaption observer of variable structures (SMMRAS) was investigated to the PMSM sensorless control. A method which used a continuous function to replace the switching function in traditional SMMRAS was presented. The design method of sliding surface and adaptive rate was also presented. A block diagram of optimized SMMRAS algorithm to identify motor speed was presented with rigorous math proof. This method was tested on the MATLAB. The results show that the model reference adaption observer of variable structures effectively eliminates the system shock causes by frequent switching, and the interference from motor parameter. It also has a good stability over a wide speed range.

Key words: PMSM; variable structure; MRAS; speed sensorless