An on-line rotor resistance estimator for induction machine drives

Rotor resistance variation due to changing rotor temperature is a significant issue in the design of induction motor controls. In this work, a new on-line rotor resistance estimator is proposed based on an alternate qd induction machine model which simultaneously includes stator leakage saturation, rotor leakage saturation, magnetizing path saturation, and distributed circuit effects in the rotor conductors. Computer simulation studies demonstrate the ability of the estimator to accurately track rotor resistance variation. Experimental studies demonstrate that an adaptive maximum torque per amp control which utilizes the proposed estimator significantly outperforms a maximum torque per amp control without rotor resistance adaptation