Fuzzy Logic-Based Direct Torque Control for Induction Machine Drive

Direct torque control (DTC) of induction machines presents an acceptable tracking scheme for both electromagnetic torque and stator flux. However, conventional DTC scheme, based on hysteresis comparators and the switching table, suffers from large torque and flux ripples, requiring high switching frequency operation for the voltage source inverter. In this paper, a modified DTC scheme based on fuzzy logic rules is proposed. A fuzzy controller (FC) is designed in order to give the appropriate inverter voltage vector. The FC could judge the deviation degree of the torque and flux errors to select the optimum voltage vector according to the fuzzy logic inference. The effectiveness of the proposed FC-based DTC for induction machine (IM) drive is verified at several operating conditions and highlighted by comparing to the conventional DTC. The obtained results illustrate low switching frequency, considerable ripples mitigation of torque, flux and the stator currents and improving the system performance.