A robust field oriented control of induction motor with flux observer and speed adaptation

A new sensorless integral sliding mode control for induction motors which provides global asymptotic speed tracking in the presence of unknown parameters and load torque is presented. First, an improved method of speed estimation that operates on the principle of a speed adaptive flux and current observer has been proposed. An observer is basically an estimator that uses a plant model and a feedback loop with measured stator voltages and currents. Then a sliding mode controller with an integral switching surface is investigated. The stability analysis of the proposed controller under parameter uncertainties and load disturbances is provided using the Lyapunov stability theory. Finally simulated results show that the proposed controller with the proposed observer provides high-performance dynamic characteristics and that this scheme is robust with respect to plant parameter variations and external load disturbances.