DC offset and parameter compensated stator flux estimator of sensorless vector controlled induction motor drive

A stator flux field oriented vector control design and implementation of sensorless three phase induction motor (IM) is presented in this paper. In proposed control scheme, the reference values of speed and stator flux are delivered to the nonlinear controller which consists of 5 separate PI controllers. A two level space vector modulation (SVM) inverter is employed to generate the required stator voltage. Moreover, using the fifth order model of three phase IM in the stationary reference frame, a nonlinear stator flux observer is developed which is capable of rotor and stator resistances and rotor speed simultaneously estimation. A useful method is also presented for DC offset compensation which is a major problem of AC drives especially at low speeds. Simulation and experimental results are presented to confirm the effectiveness of the proposed method.