PID Nested Higher Order Nonsingular Terminal Sliding Mode Observer for Speed Estimation in PMSM Servo Drive

In this paper, a PID nested higher-order nonsingular terminal sliding mode observer is proposed for speed estimation of Permanent Magnet Synchronous Motor (PMSM). Here, the introduction of PID error embedded into the nonsingular terminal sliding manifold, which is now at higher order, smoothen the observer's control input, leading to significant chattering reduction as well as better accuracy and faster response of the resulted-in back-EMF and rotor's electrical angle estimation. The simulation and experimental results demonstrate the effectiveness and advantages of the proposed approach.