Adaptive rotor flux observer for rotor time constant tuning in induction motor drives

Field oriented control of induction motor drives needs the detection of rotor flux which is usually detected by means of an observer. Rotor time constant variation due to rotor heating de-tunes the observer and, hence, the field oriented control. In the present paper an adaptive observer is synthesized, which allows the on-line rotor time constant tuning. The identification of the rotor time constant is performed by a model reference approach. The synthesis of the adaptive observer is conducted using the Lyapunov stability theory applied to the drive-observer system. The simulation results evidence the good performance of the proposed observer and, hence, of the overall controlled drive. In particular, the interactive effects between the observer and the parameter identifier gains is evidenced.