Backstepping control of the induction machine with a sliding mode observer

In this paper, a backstepping controller of Induction Motor (IM) is proposed using the fourth order model in fixed two frame reference axis with rotor flux and stator currents as state variables. The approach of backstepping requires, generally, that the nonlinear system is in strict feed-back loop. To implement this strategy over the IM, some transformations on the model (α, β) of the machine have been carried out without recourse to the oriented flux hypothesis which allows a triangular state representation. The overall system stability is proved by Lyapunov theory. Indeed the controller relations hip depends on the unmeasured states of the IM, and a sliding modeobserver is used in order to reconstruct the motor speed, the rotor flux and the load torque. Simulation results are provided to illustrate the effectiveness of the proposed approach and the robustness to uncertainties, such as moment of inertia variations.