Research on speed estimation algorithm for induction motor drive

This paper presents an analytical study on the two new types of MRAS based speed estimator, one based on the rotor BEMF and the other based on the rotor reactive power. The unstable nature of reactive power based MRAS scheme is demonstrated in detail. As the preferred scheme, BEMF based MRAS speed estimator is also found disadvantageous in dynamic performance and noise immunity. Therefore, several methods are applied to form a new modified MRAS speed estimator, based on which a sensorless vector controlled Induction motor drive system is set up. Experimental verifications are finally present to show the feasibility of such a new speed estimator.