A MRAS method for sensorless vector control of induction motor based on instantaneous reactive power

A MRAS (Model Reference Adaptive System) method for evaluation of induction motor speed to achieve speed sensorless vector controlling by the variation of transient reactive power is discussed in terms of traditional methods. A mathematic model is derived, and the reliability of the speed estimator is performed in speed-torque domain using small signal analysis. The simulating model of speed-sensorless system found on MATLAB/SEVIULINK is given. In this paper, the MRAS utilizes instantaneous reactive power in the reference and adjustable models, so the error between the two models during transient is less and the transient performance of the estimator is improved. Simulation results show that the discussed method is feasible.