Optimal Duty Cycle Method to Suppress the Commutation Torque Ripple of Brushless DC Motor in Braking Mode

This paper proposes an optimal duty cycle method to suppress the commutation torque ripple under the braking condition of the brushless DC motor (BLDCM). The commutation torque will also fluctuate in the braking process, but the current loop and change trend are different from that of electric operation. Therefore, it is necessary to study the commutation torque ripple under braking. To directly analyze the interfering factors of commutation torque ripple, the formulas of commutation torque ripple under the standard brake modulation mode are derived in this paper. Based on the mathematical analysis, an optimized duty cycle method is proposed to suppress the commutation torque ripple by dynamically adjusting the duty cycle during commutation period to make the target formula of torque ripple zero. The simulation and experimental results show that this method can effectively reduce the commutation torque ripple, and it is helpful for the promotion of the braking performance and the scope of application of the brushless DC motor.