Robust torque control of induction motors with power factor optimization: experimental evaluation

This paper presents experimental results of a robust nonlinear torque controller for induction motors based on the optimization of the power factor of the machine. This type of controller, which has been designed by Canudas de Wit at. el (1992), first derives the optimal operating points (steady-state values for currents and flux) parameterized in terms of the desired motor torque and then stabilized through a static state about the machine optimal operating points. We have implemented the nonlinear PI-observer-based controller. The PI-structure and the observer-based control are introduced to deal with motor parameter uncertainties and the absence of rotor flux measurements, respectively. This controller ensures torque regulation despite uncertainties on the electrical parameters of the machine. The experimental validation was made on a small machine of 1.1 kW