Brushless DC motor optimization based on direct torque control

Combining the characteristics of brushless DC motor, based on the analysis of the traditional direct torque control with two two conduction, the direct torque control scheme based on extended park transform with three full conduction for brushless DC motor is proposed for the problem of large torque pulsation in the existing direct torque control with phase change. In order that the system can effectively suppress the torque fluctuation caused by the non-ideal counter potential the scheme uses the extended park transform to decompose the current and counter potential waveform constants, and the observed torque and magnetic chain are controlled in a double hysteresis loop, and the applied voltage vector is determined according to the torque and magnetic chain loop outputs and pole positions. Also, to reduce the torque error caused by phase change, a three-phase conduction strategy is used for motor drive. Simulation and experimental results show that the optimized direct torque control system has good torque dynamic response and steady-state performance.