Improved Direct Torque Control for Induction Machine Drives Based on Fuzzy Sector Theory

Here, a new fuzzy direct torque control algorithm for induction motors isproposed. As in the classical direct torque control, the inverter gate control signals directlycome from the optimum switching voltage vector look-up table, the best voltage spacevector selection is a key factor to obtain minimum torque and flux ripples. In the proposed approach, the best voltage space vector is selected using a new fuzzy method. A simulation model is built up and the torque and flux ripples of basic direct torque control and the proposed method are compared. The simulation results show that the torque and fluxripples are significantly decreased and in addition, the switching frequency can be fixed.