Induction motors direct field oriented control with robust on-line tuning of rotor resistance

This paper proposes an alternative rotor resistance identification method used in the frame of a direct field oriented control (DFOC) of induction motors. The authors investigate the use of the induction motor instantaneous reactive power for rotor resistance identification on the basis of the model reference adaptive system (MRAS) method. In fact, from a practical point of view, the instantaneous reactive power can give quite sufficient real time information on the induction motor behavior. The proposed identification method can be achieved with on-line tuning of the inverse rotor time constant with robustness against stator resistance variation. Computer simulations are given to highlight the feasibility, the simplicity, and the robustness of the proposed method.