Speed Sensorless Control of Induction Motor

Abstract

The developments of vector control strategy in Induction motor have been extensively preferred in the industries for variable speed drives. Vector control strategy requires speed encoders, which cause extra cost, reliability, maintenance problem. Therefore, there is high interest in researcher to develop a speed sensorless control of induction motor drive. There are many speed estimation techniques used for this purpose. Among all the speed estimation techniques, model reference adaptive system (MRAS) gains its popularity due to high disturbance rejection, robust and simple in implementation. In MRAS techniques, reference model and adaptive model are used. Reference model is taken as fixed model and it is independent from rotor speed. Adaptive model is taken as speed dependent model. Output of adaptive model is compare with reference model and processed through a PI controller to get estimated speed. In this speed estimation technique, rotor speeds information is derived from stator voltage and current at motor terminals.