Direct torque control improvement of a variable speed DFIG based on a fuzzy inference system

Abstract

In this paper, a fuzzy direct torque control (DTC) for a variable speed doubly fed induction generator (DFIG) based wind turbine is investigated. The DTC has been widely applied to doubly fed induction machines in recent years due to the high performances that it provides in comparison with the classical field oriented control. Meanwhile, it has a major drawback that is the significant torque and flux undulations generated by the hysteresis band controllers. To overcome this problem, the improvement of this technique by removing these controllers is proposed in this paper. The proposed control technique is based on replacing the hysteresis controllers by a fuzzy inference system which will have the same inputs as these controllers plus the sector angle determination so that the look-up table can be replaced by a fuzzy rule-base matrix. The simulation was performed in MATLAB/SIMULINK, and the results obtained make it possible to evaluate the performance of the proposed technique over the classical one.