A reduced order rotor time constant and flux estimator for vector controlled induction motor

A reduced order estimation algorithm for on-line identification of rotor time constant and rotor flux of an induction motor is proposed in this paper. The algorithm is based on the measurement of stator voltage, current and rotor speed, and uses an extended Kalman filtering technique. The covariance matrices of noise, which are important in Kalman filtering, are established using a simple and practical method that is proposed here. A squirrel-cage induction machine is fed from a six step PWM inverter, and from a sinusoidal source at different times in order to observe the performance of the proposed estimator for different operation conditions. Both simulation and implementation results showed that the proposed algorithm can be used successfully to identify the rotor time constant and rotor flux of induction machines.