Torque ripple reduction of the BLDC motor using a modified 3-phase conduction method

BLDC(Brushless DC) motor has an excellent torque characteristics, but the non-linear back EMF and unbalance current at the commutation region can make torque ripple in the practical application. In this paper, the modified 3-phase conduction method is presented to reduce the commutation torque ripple of the BLDC motor. The simple linear TAF(Torque Activation Function) is designed to reduce the commutation torque ripple. Then the PWM(Pulse Width Modulation) duty ratio of the medium phase is simply compensated by the designed TAF during commutation region. And the switching pattern to reject the commutation torque ripple is proposed with the modified 3-phase conduction method. The proposed switching method can reduce the switching loss compare than the conventional 3-phase conduction method with the reduce torque ripple than the 2-phase conduction method. The calculation of the switching voltage in the proposed method is detailed explained in the conduction and commutation region to reduce the torque ripple of the BLDC motor. The proposed control scheme is verified by the simulation and experimental results.