Simulation research of direct torque open-loop control system based on MATLAB

In the asynchronous motor direct torque control system, the size of flux tolerance determines the switching time of non-zero voltage vector, and affect the hexagonal flux trajectory. If the flux unchanged, through a given torque and actual torque difference to adjust the voltage vector in each sector of the imposed time to keep the torque stability within the tolerance range. The size of the torque tolerance affect switching state of the converter switching frequency and torque ripple size. Use MATLAB/simulink simulation model to establish the open-loop direct torque control system in this paper. The simulation results show that the smaller tolerance, the greater inverter switching frequency and greater pulse of system. In the conduction of constant speed, increase the system load, it need to increase applied time of the nonzero voltage vector in the same sector.