Sensorless Fault Tolerant Control for Induction Motors Using: backstepping strategy and Sliding Mode Observer

In this paper, a sensorless output feedback controller is designed and developed for the Induction Motor (IM), without using of flux and speed sensors. Firstly, a new sliding mode observer that uses only the measured stator currents is synthesized to estimate the speed, the flux and the load torque. Secondly, a backstepping control is developed so as to steer the estimated speed and flux magnitude to the desired references. Stability analysis based on Lyapunov theory is also presented in order to guarantee the closed loop system (controller + observer) stability of the proposed observer-control system. In the proposed approach, a robust controller based on backstepping strategy is designed in order to compensate both the load torque disturbance and the rotor resistance variations caused by the broken rotor bars faults. The proposed approach needs neither fault detection and isolation schemes nor controller reconfiguration. To highlight the efficiency and applicability of the proposed control scheme, simulation results are conducted for a 1.5kWinduction motor.