Speed Estimation Chemes for Sensorless Vector Control of Induction Motor Drive

This paper describes the speed estimators for sensorless vector control of induction motor drive. Speed and rotor fluxes of the induction motor are estimated by adaptive rotor flux observer, natural observer with load torque adaptation and Extended Kalman Filter (EKF). The performance parameters speed and rotor fluxes are estimated from the measured terminal voltages and currents. Fourth order induction motor model is used in natural observer and adaptive rotor flux observer and speed is considered as a parameter. In EKF algorithm, fifth order model is used and speed is considered as a parameter and state. Direct filed oriented control is used in all the estimators. The speed of an induction motor is estimated by MATLAB simulation under different speed and load conditions. The estimated parameters along with speed are used for closed loop control.