Research on the Method of Reducing Phase Change Torque Pulsation of Brushless DC Motor

Aiming at the problem of torque pulsation at the moment of phase change of brushless DC motor, a smooth phase change control method of “on-phase fully open, off-phase large duty cycle open, and non-commutated phase hold” is proposed. This method takes the smooth transition of non-commutated phase current as the goal, calculates the duty cycle of the on-phase and off-phase, determines the time of phase change, and realizes the smooth transition of non-commutated phase current at the moment of phase change, and realizes the unified control of high-speed and low-speed zones based on the effective suppression of the pulsation of commutated current, avoiding the problem of unclear zoning. The experimental waveforms show that this method has obvious inhibition effect of phase change current at the moment of phase change, and the torque pulsation coefficient of the motor in the full-speed section is about 0.1.