Integral sliding-mode controller for induction motor based on field-oriented control theory

Abstract

A novel sensorless integral sliding-mode control for induction motors is discussed. Besides, the control scheme provides global asymptotic speed tracking in the presence of unknown parameters and load torque. For this purpose, the control scheme makes use of an improved method of speed estimation operating on the principle of a speed adaptive flux and current observer. As it is known, an observer is basically an estimator that uses a plant model and a feedback loop. In particular, an observer is constructed, which provides a speed estimation on the basis of the measured stator voltages and currents. Then a sliding-mode controller with an integral switching surface is considered. The closed-loop stability of the proposed controller is proved under parameter uncertainties and load disturbances, using the Lyapunov stability theory. Simulated results show that the proposed controller, jointly with the proposed observer, provide high-performance dynamic characteristics and that this scheme is robust with respect to plant parameter variations and external load disturbances. Finally, the feasibility of the proposed control scheme is proved by means of experimental results over a real induction motor.