A novel control strategy for brushless DC motor drive with low torque ripples

The traditional control methods of brushless DC motors lead to great commutation torque ripples. In order to improve the torque performance, this paper proposes a control strategy based on brushless DC motors´ torque equation. In this strategy, the phase currents should be well controlled during commutation process to reduce the derivative of scalar product of three-phase currents and electromotive forces, i.e., the ripples of electro-magnetic torque. Two kinds of voltage control methods for reducing torque ripples are presented, which are the method of constant current in no-commutation phase and minimum torque ripples method. The simulation and experimental results are presented to demonstrate the effectiveness of the new control strategies.