Instantaneous torque ripple control in brushless DC motors based on conduction PWM duty ratio

In this paper, the duty ratio in conduction region is used to separate the high speed and low speed area in BLDCM. In the low area, the PWM method is used to eliminate the torque ripple. And in the high speed area, overlapping commutation technology and PWM method are used at the same time to reduce the torque ripple. The duty ratio in the commutation region of the PWM method can be gotten from the duty ratio in conduction region directly. This method is very simple and more precise. Simulation and experimental results show it´s easy to realize and make brushless DC motor suitable for high precise applications.