Reduced-order observers for rotor flux, rotor resistance and speed estimation for vector controlled induction motor drives using the extended Kalman filter technique

The paper deals with robust parameter estimation (rotor and stator resistances), shaft speed estimation, and flux observation of induction motors using the extended Kalman filter (EKF) technique. The novelty of the paper is that it develops the EKF in a frame rotating synchronously with the stator current vector with the use of a reduced dynamic motor model in order to economise the computational requirements of the EKF. Different problems have been studied. First, the EKF technique is applied to the estimation of the rotor and stator resistances. This is used for the indirect field-oriented control of the induction machine. Next, the EKF technique is applied to the estimation of the induction machine rotor fluxes and rotor resistance, and is used to perform the direct field oriented control of the induction machine. Finally, speed sensorless control is carried out. In this case, the rotor flux and the motor shaft speed are estimated. Computer simulations and experimental tests have been carried out to show the effectiveness of the proposed methods.