Flux estimation by Kalman filter in inverter-fed induction motors

Inverter-fed induction motor drives play an important role in the field of industrial automation because the motors behave like DC machines when the field-oriented control strategy is employed. For the implementation of direct field-oriented control, it is important to have information regarding magnitude and position of the rotor flux vector. The authors with a simple scheme suitable to estimate the rotor flux components. In this scheme the stator flux components and the stator angular frequency are assumed to be the state variables. Because the state variable model and the observation equation are nonlinear, the procedure is based on the extended theory of the Kalman filter. In the observation equation the harmonic content of the measured terminal quantities is treated as noise and rejected. The feasibility of the proposed scheme has been tested by digital simulation and some results are reported