Adaptive sliding-mode observer for speed-sensorless control of induction motors

This paper presents an adaptive sliding-mode observer for the speed-sensorless field-oriented control of induction motors. The observer detects the rotor flux components in the two-phase stationary reference frame by the motor electrical equations. The motor speed is estimated by an additional relation obtained by a Lyapunov function. The analytical development of the sliding observer and the speed estimation algorithm is fully explained. Experimental results are presented, based on a TMS320F240 digital signal processor controller implementation. The system performance with different observer gains and the influence of the motor parameters deviations are shown and discussed.