Discontinuous Sliding Surface For a General Electromechanical System with Time-Invariant Uncertainties

A new design approach of a sliding mode controller for a generalized electromechanical system with mismatched time-varying uncertainties is presented in this paper. A discontinuous sliding surface can be designed to satisfy a new matching condition, and two layers of sliding surfaces are considered. By maintaining the sliding mode on the first surface, the second layer can be reached in finite time. It is shown that the system is invariant on the sliding surface, and the stability of the closed-loop system is guaranteed. A magnetic levitation example is used to prove the effectiveness of the proposed control scheme.