Sliding mode controller design for high performance of permanent magnet stepper motor

This paper seeks to achieve simple, yet efficient modelling and control scheme for a permanent magnet stepper motor wherein a control law is developed based on sliding mode that provides robustness against uncertainties, parameter variations and perturbations for accurate trajectory tracking of motor position and current. The stability analysis guarantees the asymptotic stability of the origin in finite time. Under bounded disturbance and a switching manifold that enforces trajectory tracking, a control algorithm is presented to drive the states quickly on the stable sliding mode manifold and to constrain them thereafter. Further, efforts have been made to achieve the characteristics of a smooth controller by making the continuous approximation of the discontinuous law.