Improved Full-Speed Sensorless Control Strategy for Permanent Magnet Synchronous Motors

This paper presents a novel sensorless control strategy for permanent magnet synchronous motors (PMSM) across the entire speed range. The strategy utilizes an improved hybrid approach to achieve robustness against parameter disturbances. To enhance control performance, a sliding mode velocity controller is introduced to the system. Moreover, a modified sigmoid function is proposed for the sliding mode observer (SMO) of the motor, effectively mitigating the chattering phenomenon experienced in traditional SMOs at medium to high speeds. To optimize sensorless control effectiveness, an enhanced hybrid weighting allocation method is proposed. This method precisely delineates speed regions and maximizes the utilization of each strategy within the hybrid control framework. By incorporating two constants representing maximum error rates, the issue of transitioning from low-speed to high-speed sensorless control is effectively addressed. The proposed rotor position and speed estimation scheme are further validated through simulation conducted at different speeds. The results demonstrate the effectiveness and accuracy of the proposed approach.