Robust control of an induction machine drive using a time-varying sliding surface

In this paper, a variable structure position control law for an induction motor with a field-oriented control strategy is proposed. The algorithm, based on a time-varying switching line, guarantees the existence of the sliding mode since the beginning of the shaft motion. Indeed, the switching line is initially designed to pass through the initial representative point and subsequently moved towards a predetermined desired surface via shifting. By this mean, the reaching phase is eliminated and the motor behavior is insensitive to unknown mechanical configuration changes. The algorithm has been tested in simulation for evaluated the robustness capacities.