Novel Composite Sliding Mode Control for PMSM Drive System Based on Disturbance Observer

This paper introduces a sliding mode control (SMC) scheme to solve time-varying parameters and disturbances for a permanent magnet synchronous motor (PMSM) drive system. A new speed controller is designed by the nonsingular terminal sliding mode control (NTSMC) strategy with the disturbance observer (DOB). The controller can make the motor speed reach the reference value in finite time, accompanying with a faster convergence and a better tracking precision. Considering the time-varying characteristic and the high-bandwidth property of the uncertainties and disturbances in a practical PMSM drive system, the common SMC method needs to provide large gain to restrain disturbance with large chattering. A DOB is introduced as a compensator to resist disturbance and to reduce control gains. By applying a DOB as the feed-forward compensator and the NTSMC as the feedback controller, one new composite NTSMC scheme has been proposed for the speed control of PMSM under disturbances and uncertainties with small chattering since smaller switching gain are required by the proposed scheme. The validity and robustness of the scheme are fully verified by comprehensive simulations and experiments.