Sensorless robust control of PMSM based on a closed-loop observer

Noting the different characters of interior permanent synchronous motors (IPMSM) in the stationary reference frame and the rotating reference frame, a closed-loop sliding-mode observer was designed to directly estimate the rotor position, based on which the rotor speed was estimated. Because the speed estimation errors do not affect the performance of the observer, the estimation accuracy of the observer is improved obviously. In consideration of the motors´ operating performance degradation due to parameters perturbations and load disturbances, an adaptive sliding-mode controller based on integral switching function was designed and the speed control law was obtained by the Lyapunov stability analysis. The satisfactory control performance and the robustness of the system are verified by the simulation results.