Variable-structured robust control by fuzzy logic and stability analysis for AC drive system

This paper proposes a gain scheduling robust controller whose structure is continuously changed by fuzzy logic such that the controller makes the system respond quickly if the error e is large and vice versa in order to obtain a robust controller which is insensitive to both the plant noise and the observation noise. Then, it is practically applied to speed control for an induction servomotor. Experiments show that the proposed controller is superior to both a sliding mode controller and a PID controller. The paper includes the stability analysis of the overall system and the design procedure by using Lyapunov´s method