A robust torque controller for induction motors without rotor position sensor: Analysis and experimental results

A robust controller, which tracks flux and torque commands is designed for an induction motor. It is based on a transformation to the estimate of the rotor flux. The speed of the rotor is estimated from the stator currents us ing a high-gain observer. The controller is robust with respect to variatio ns of the rotor resistance. Analysis of the controller shows that the syste m is asymptotically stable in the motoring and brakeing regions and in the generating region for large enough torque reference. Simulations and experi mental results show agreement with the analysis.