Delay-dependent robust control for uncertain discrete stochastic fuzzy systems via relaxed LMIs

A novel fuzzy sliding-mode structure has been proposed for Exend Kalman Filter(EKF) based sensorless control of an induction motor in this paper. The design includes a Extend Kalman Filter(EKF) from measured stator terminal voltages and currents. The estimated speed is used as feedback in an indirect vector control system achieving the speed control without using shaft mounted transducers. Fuzzy sliding-mode structure includes two nonlinear controllers, one of which is sliding mode type and the other is PD-fuzzy logic based controller, The latter define a new control structure. Both controllers are combined by means of an expert system based on Takagi-Sugeno fuzzy reasoning. The sliding mode controller acts in the steady state. The new structure has two advantages: sliding-mode controller increasing system stability and PD-like fuzzy logic based controller reducing the chattering in permanent state. The scheme has been implemented and experimentally validated.