Application of Variable Structure Theory to Direct Field-Oriented Induction Motor Speed Controllers

In this paper an variable structure speed controller for induction motor(IM) is developed, which combines the merits of sliding mode variable structure theory, direct field-oriented control (DFOC) and adaptive algorithm. Firstly, a sliding mode controller is designed and the adaptive algorithm is adopted to adjust the sliding gain in order to restrain chattering. And then a sliding mode flux observer is used to observe the rotor flux accurately. All the control strategies are derived in the sense of Lyapunov stability theory so that the stable tracking performance can be guaranteed under the occurrence of system uncertainties and external disturbances. Finally, some simulation results are provided to validate the effectiveness and robustness of the proposed control scheme.