Speed control of induction motors using a novel fuzzy-sliding mode structure

This paper presents a new approach to indirect vector control of induction motor. Two nonlinear controllers, one sliding mode and the other PI-fuzzy logic based, define a new control structure. Both controllers are combined by means of an expert system based on Tanaka and Sugeno fuzzy reasoning. The sliding mode controller acts mainly in the transient state while the PI-like fuzzy controller acts in the steady state. The new structure is assumed to embody the control advantages that both nonlinear controllers offer: sliding mode controllers present robustness, increasing system stability limits; and PI-like fuzzy logic based controllers have been used to improve steady state features, specially in nonlinear systems. The scheme has been implemented and experimentally validated.