Second order sliding mode sensorless torque regulator for induction motor

In this paper the torque and the square of the rotor fluxes magnitude using a second order sliding mode (SM) controller for an induction motor, is proposed. The main contribution of the control scheme presented here is the output regulation as well as the asymptotically stabilization of the zero dynamics. The sliding manifold is designed such that the speed zero dynamics become asymptotically stable on this manifold. To enforce the SM motion on the designed manifold a super-twisting SM algorithm is used. This algorithm permits to reduce chattering that is inherent in standard sliding mode control and to improve accuracy. The rotor fluxes and speed are estimated by means of an adaptive observer, whereas the estimate of the load torque is obtained via design of a robust differentiator. The effectiveness of the designed observer-control scheme is confirmed via simulation.