Commutation torque ripple reduction in brushless DC motor based on equivalent voltage coefficient control

This paper presents a novel method to inhibit the commutation torque ripple in a brushless dc motor based on the analysis of equivalent voltage coefficient. The equivalent voltage coefficient is analyzed at low speed with PWM in incoming phase and at high speed with PWM in outgoing phase separately. By setting the equivalent voltage coefficient in commutation period to the conduction period, commutation torque ripple is significantly reduced. Simulation and experimental results show the validity of this control technique.