Sliding-mode control of an induction motor without flux measurement

A new approach to controlling the speed and rotor flux of an induction motor using sliding-mode theory is presented. Sabanovic´s equations for an induction motor are first modified to a state-space form suitable for the present design of the algorithm. A simple control algorithm that is based on the existence of a certain positive definite matrix is proposed. The Lyapunov direct method is used to ensure reaching and sustaining of the sliding-mode. To avoid direct measurement of the rotor flux, a technique based on manipulation of Stanley´s equations is introduced. Simulation studies were conducted. The control algorithm exhibited excellent drive performance in the presence of load disturbances and stator and rotor resistances changes of up to 100% of the nominal values.<>