A New Approach of Minimizing Commutation Torque Ripple for Brushless DC Motor Based on DC–DC Converter

Brushless dc motor still suffers from commutation torque ripple, which mainly depends on speed and transient line current in the commutation interval. This paper presents a novel circuit topology and a dc link voltage control strategy to keep incoming and outgoing phase currents changing at the same rate during commutation. A dc-dc single-ended primary inductor converter (SEPIC) and a switch selection circuit are employed in front of the inverter. The desired commutation voltage is accomplished by the SEPIC converter. The dc link voltage control strategy is carried out by the switch selection circuit to separate two procedures, adjusting the SEPIC converter and regulating speed. The cause of commutation ripple is analyzed, and the way to obtain the desired dc link voltage is introduced in detail. Finally, simulation and experimental results show that, compared with the dc-dc converter, the proposed method can obtain the desired voltage much faster and minimize commutation torque ripple more efficiently at both high and low speeds.

I. Introduction

Brushless DC MOTOR (BLDCM) has been widely used in industrial fields that require high reliability and precise control due to its simple structure, high power density, and extended speeding range [1]–[3]. The performance of such motors has been significantly improved due to the great development of power electronics, microelectronics, magnetic performance of magnets, and motion control technology in recent years [4]–[9]. However, commutation torque ripple, which usually occurs due to the loss of exact phase current control, has always been one major factor in preventing BLDCM from achieving high performance. So far, many studies have been performed to reduce commutation torque ripple [9]–[21].