I. Introduction
Brushless DC (BLDC) motor is widely used in industrial applications due to its high efficiency, sample structure and easy-to-control features [1]–[2]. However, torque ripple commonly existing in the BLDC motor restricts its application in high precision drive system. The torque ripple in BLDC motor is caused by many reasons, especially the commutation torque ripple. Hence, suppression of commutation torque ripple becomes the key to reduce the BLDCM torque ripple.