A Control Strategy to Suppress Torque Ripple of Brushless DC Motor

The paper proposes an advanced communication control strategy aiming at the problem of torque ripple during the commutation process of Brushless DC motor (BLDCM). By commutating in advance, the slope of off-phase current and conduction-phase current are adjusted. By comparing and analyzing the equilibrium equation of three-phase current in case of different commutation leading angle, a conclusion can be drawn from the analysis that the decaying rate of off-phase current is fundamentally the same as the increasing rate of conduction-phase current, and the torque ripple is minimum, when commutates 60 electrical degree in advance. Besides, for suppressing the freewheeling current of three-phase bridge inverter circuit caused by commutating in advance, a topology is proposed. The theoretical analysis shows that, the proposed method can reduce the torque ripple during the commutation process, and improve the control precision of BLDCM system.