Sensorless control of induction motor using EKF: Analysis of parameter variation on EKF performance

This paper deals with the investigation of the Extended Kalman Filter (EKF) for sensorless indirect vector control of an induction motor. The prime focus is low speed operation, when the EKF somewhat presents erroneous results. The effectiveness of the EKF as a speed estimator under machine parameter variations - change in stator resistance, rotor resistance is assessed. Furthermore, the effect of the changes in the measurement co-variance and error covariance matrices have been discussed using simulation and experimental results. Finally under low speed operation a relation between the error covariance matrices and machine parameter variations, for performance improvement of the induction motor, is established.