Robust fuzzy variable structure control of PMLSM servo system

The paper proposes a new position control strategy which is robust against load disturbance, torque ripple and parameter variations. The strategy is an expansion of disturbance observer based on acceleration control loop. According to the current and position information, the disturbance observer estimates the disturbance and parameter variations and constructs the feedforward force loop. As a robust control system based on disturbance observer sometimes has high overshoot and oscillated response, both the feedback controller and disturbance observer adopt fuzzy variable structure construction so that observer noise is suppressed. The effectiveness of the proposed controller is verified by experimental result. Disturbance suppression and improvement of phase delay are attained