SLIDING-MODE CONTROL OF AN INDUCTION-MOTOR WITHOUT FLUX MEASUREMENT

A new approach to control the speed and rotor flux of an induction mot or using the theory of the sliding-mode is presented. Sabanovic's equa tions for an induction motor are first modified to a state space form suitable for the present design of the algorithm. For controlling the speed and rotor flux of the drive, a simple control algorithm is propo sed based on the existence of a certain positive definite matrix. Lyap unov direct method is used to ensure the reaching and sustaining of sl iding-mode. Obviation of flux measurement is achieved through manipula tion of Stanley's equations. Simulation studies are conducted. The con trol algorithm exhibits excellent drive performance in the presence of load disturbances and stator and rotor resistances changes up to 100% of the nominal values.