Commutation Torque Ripple Reduction for Brushless DC Motors Based on Optimal Control

A method based on optimal control is proposed to reduce the commutation torque ripple of brushless dc motors (BLDCMs) in this paper. The theoretical background on optimal control and its design process when applied to BLDCM for commutation torque ripple reduction are given. According to the proposed method, the optimal switching state is selected and applied in the commutation period directly, which makes the non-commutated phase currents stable. Therefore, the commutation torque ripple of the BLDCM is reduced. Simulation results show the effectiveness of the proposed strategy in both high-speed and low-speed conditions as compared to that of the conventional control method.