A VSS speed controller with model reference response for induction motor drive

This paper is mainly concerned with the development of a variable-structure system (VSS) controller with model reference speed response for an inducti on motor drive. An indirect-field-oriented (IFO) induction motor drive is f irst implemented, and its dynamic model at a nominal operating condition is estimated from measured data. Then, a two-degrees-of-freedom linear model- following controller (2DOFLMFC) is designed to meet the prescribed tracking and load regulation speed responses at the nominal case. As the variations of system parameters and operating condition occur, the prescribed control specifications may not be satisfied further. To improve this, a VSS contro ller is developed to generate a compensation control signal to reduce the c ontrol performance degradation. The proposed VSS controller is easy to impl ement, since only the output variable is sensed. The existence condition of sliding-mode control is derived, and the chattering suppression during the static period is also considered. Good model-following tracking and load r egulation speed responses are obtained by the designed VSS controller. Effe ctiveness of the proposed controller and the performance of the resulting d rive system are confirmed by some simulation and measured results.