The study on the constant switching frequency direct torque controlled induction motor drive with a fuzzy sliding mode speed controller

This paper presents a high performance direct torque control (DTC) theme for the induction motor (IM). To solve those problems associated with conventional DTC, such as high current, flux and torque ripple, variable switching frequency, the space vector modulation (SVM) is implemented in the DTC to guarantee the constant switching frequency of the inverter. Meanwhile, the design of a robust speed controller based on fuzzy sliding mode control (FSMC) is proposed, in which a fuzzy logic controller replaces the discontinuous part of the classical sliding mode control law. The simulation results of the proposed theme present good dynamic and steady-state performances as compared to the classical DTC with proportional-integral (PI) controller from aspects of the reduction of the torque ripple, the quickly dynamic torque response and robustness to disturbance.