Improvement of Fuzzy Direct Torque Control System of Asynchronous Motor

In conventional direct torque control of asynchronous motor, band width of hysteresis controller cannot be too small because of switch frequency limit of power transistors, which unavoidably brings larger ripple of torque. To solve the problem, the paper proposed to use an improved fuzzy controller to replace the conventional hysteresis controller, build a new fuzzy rule table according to different effects of the same voltage vector to flux and torque in different flux region, and use MOM method to achieve defuzzification. Matlab/Simulink simulation results showed that the fuzzy controller is superior to traditional hysteresis controller in decreasing ripple of torque and dynamic performance.