Direct Torque Control of Induction Motor using Robust Fuzzy Variable Structure Controller

Direct Torque Control (DTC) algorithm for induction motor drives gives fast transient response. The classical DTC algorithm utilizes a proportional integral (PI) speed controller to generate the reference torque value. Though this is quite effective, it is sensitive to parameter variation. To overcome this problem, this paper presents a fuzzy variable structure controller (FVSC), which improves the robustness of the drive. The proposed speed controller algorithm consists of switching a different control structure at each side of a given switching surface according to a predefined switching function. Hence, the system responds with a sliding mode on the switching surface, and in this mode the system is insensitive to parameter variations and disturbances. To evaluate the proposed controller, several simulation studies have been carried out under a variety of operating conditions of the drive system, and the results demonstrate the ability of the proposed control structure in improving the performance and robustness of the drive system.