ADAPTIVE OBSERVER-BASED CONTROL OF INDUCTION-MOTORS WITH UNKNOWN ROTOR RESISTANCE

An output feedback control for induction motors which is based on roto r speed and stator current measurements is presented. It is adaptive w ith respect to constant unknown torque load and rotor resistance, The main feature of this control is the incorporation of a novel adaptive flux observer which provides exponentially convergent estimates of rot or fluxes and rotor resistance under persistency-of-excitation conditi ons that are satisfied in physical operating conditions. Extensive sim ulations show that asymptotic convergence is achieved for the overall closed loop system; in particular, the true values of torque load and rotor resistance are obtained and the speed and flux level references are independently tracked.