Robust rotor flux, rotor resistance and speed estimation of an induction machine using the extended Kalman filter

This paper deals with robust flux, speed, and rotor resistance estimation of sensorless induction motor drives using the extended Kalman filter (EKF) algorithm. A reduced dynamic motor model is used which reduces the computational requirements of the EKF. The originality of the proposed structure lies in the simultaneous estimation of the shaft speed and rotor resistance. Due to this aim, the state-space vector is extended to the shaft speed and the rotor resistance. Since these two quantities are correlated, a small high frequency signal is added to the flux reference in order to permit the estimation of both quantities. Computer simulations and experimental tests have been carried out to show the effectiveness of the proposed method