A MRLS with RMRAC applied to encoderless speed control without time rotor dependence

This paper proposes a robust model reference adaptive controller (RMRAC) for a speed sensorless induction motor drive. A modified recursive least squares (MRLS) is proposed to avoid the use of mechanical sensors. The MRLS is obtained by applying of a sigma-modification in recursive least square (RLS), obtained from a linear model insensible to rotor resistance variations. The obtained controller is used to assure performance in a wide speed range, including low and zero speed conditions. Moreover, a direct estimation of the rotor flux estimation is used, so that the proposed scheme can be applied without shaft encoder and independent of the rotor resistance. Simulation results are given to show the effectiveness of the proposed controller.