A novel direct torque control using second order continuous sliding mode of a doubly fed induction generator for a wind energy conversion system

In this paper a new robust direct torque control strategy based on second order continuous sliding mode and space vector modulation of a doubly fed induction generator integrated in a wind energy conversion system is presented. The conventional direct torque control (C-DTC) with hysteresis regulators has significant flux and torque ripples at steady-state operation and also the switching frequency varies in a wide range. The proposed DTC technique based on second order continuous sliding mode control reduces flux, current, and torque ripples. It also narrows down the switching frequency variations in induction machine control. Two different sliding surfaces such as flux and torque sliding surfaces are used to control them. The error between reference and actual values are driven to respective sliding surfaces where the error is enforced to zero. Simulation results show the effectiveness of the proposed direct torque control strategy comparatively to the C-DTC one.