Sensorless hybrid control for permanent magnet synchronous motor using fuzzy sliding mode controller and two-stage filter observer

Aimed at the problems of large torque ripple, obvious chattering and poor estimation accuracy of back-EMFs in traditional PMSM (permanent magnet synchronous motor) control system with sliding mode observer, a novel reaching law based on hyperbolic sine function is suggested in the speed loop, and fuzzy control thought is used to achieve the selfturning of the parameter for the reaching law. Thus a fuzzy integral sliding mode controller based on the novel reaching law is designed in speed loop. Meanwhile, aiming to restrain the high frequency components and ripple components of back-EMFs in sliding mode observer, a two-stage filter structure based on a variable cut-off frequency low-pass filter and a modified back-EMFs observer is proposed, and the rotor position is compensated reasonably. As a result, a sliding mode observer based on the two-stage filter is designed. The stability of the proposed control strategy is proved by Lyapunov Criterion. The simulation results show that, compared with traditional sliding mode observer (SMO), the controller suggested above can obtain very nice system respond when the motor starts and is subjected to external disturbances. © 2020, Editorial Department of Control Theory & Applications South China University of Technology. All right reserved.