Improved DTC strategy of doubly fed induction motor using fuzzy logic controller

This paper presents an improved Direct Torque Control (DTC) strategy for a Doubly Fed Induction Machine (DFIM) powered by two voltage source inverters (VSI) at two levels. This strategy is based on the fuzzy logic controller. The main objective is to improve the performance of the system by reducing electromagnetic torque ripples and improving the currents shape by optimization of the total harmonic distortion (THD). The hysteresis regulators and voltage vectors selection table of the conventional DTC are replaced by fuzzy logic blocks to realize fuzzy DTC control. The two control strategies are simulated in the MATLAB/SIMULINK environment followed by a comparative analysis to validate the effectiveness of the proposed strategy. Many improvements in term of rise time, torque ripples, flux ripples and current harmonics have been done, namely stator and rotor flux ripple and torque ripple have been reduced more than 50%, 69.2% and 47.7% respectively. The stator and rotor currents THD have been reduced around 84.5% and 84.3% respectively.