Adaptive sliding mode based position tracking control for PMSM drive system with desired nonlinear friction compensation

Abstract

The output feedback position tracking control of permanent-magnet synchronous motor (PMSM) drive system is addressed in this paper. In order to obtain a differentiable disturbance theoretically, a continuous differentiable model is employed to model the nonlinear friction, and the desired velocity, rather than the measured or estimated velocity, is used in the friction compensation. Then, based on the desired friction compensation model, the reaching law based sliding mode controller is designed to make the position tracking error as small as possible in the presence of model uncertainties and load disturbance, and the gain of the reaching law is online tuned to adapt the variations of the controlled system. Moreover, a nonlinear extended state observer (NESO) is designed to simultaneously estimate the unmeasured states and unknown disturbance to guarantee the finite time stability of the proposed controller, and the designed NESO is proven to be exponentially stable and has zero estimation errors theoretically. Simulations and experimental results are given to verify the effectiveness of the proposed control scheme.