Torque ripple suppression of brushless DC motor drives using an alternating two-phase and three-phase conduction mode

Commutation torque ripple is an important factor affecting the performance of brushless DC (BLDC) motor drives. In order to suppress this torque ripple, an alternating conduction control strategy between the two-phase and three-phase conduction mode has been proposed in this study. During the non-commutation periods, the conventional two-phase conduction mode is selected to drive the BLDC motor. While during the commutation period, the commutation torque ripple is reduced by employing an alternating two-phase and three-phase conduction mode. By calculating the duty cycle of the three-phase conduction mode, which indicates whether the rate of change in current in the incoming and outgoing phase is equal during the commutation interval, the commutation torque ripple is effectively reduced, while the current in the non-commutated phase is maintained constant. Simulation and experimental results show that the proposed method can suppress the commutation torque ripple efficiently, particularly at high rotational speeds of the motor.