Sensorless Vector Control for PMSM System Based on Variable Structure MRAS Observer

In order to reduce the traditional model reference adaptive system( MRAS) speed observer's sensitivity to the load and motor parameters changes,based on variable structure technology,a variable structure MRAS identification method is proposed for permanent magnet synchronous motor( PMSM). The method,using sliding mode variable structure substitutes the self-adaptation principle of MRAS and using Sigmoid substitutes switching function symbols,can reduce sliding mode jitter. Theoretical analysis and simulation results show that this method has good dynamic and static performance. Based on variable structure MRAS observer PMSM sensorless vector control system has good dynamic and static performance,and has strong robustness.