MRAS based speed sensorless vector control of Induction motor

In this paper sensorless vector control of Induction motor (I.M.) using Model Reference Adaptive system (MRAS) is reviewed. Generally the performance of induction motor is poor at very low speed. It has significant effect on steady state and dynamic performance of the drive system. This can be improved by closed loop observer to estimate the state variables. MRAS is speed estimation method having two models namely reference and adaptive model. The error between two models estimates induction motor speed. MRAS is used to estimate the I.M. rotor speed and stator resistance and these are used as feedback signals for the field oriented control (FOC). The various closed loop observer are reduced order observer, kalman filter and sliding mode observer.