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 using a high-gain observer. The controller is robust with respect to variations of the rotor resistance. Analysis of the controller shows that the system is asymptotically stable in the motoring and braking regions and in the generating region for large enough torque reference. Simulations and experimental results show agreement with the analysis.