Investigation of Key Parameters on Cogging Torque in Permanent Magnet Machines Based on Dominant Harmonic Contents

The investigation of design parameters on the cogging torque has been a classical and common research subject over the last few decades. Nevertheless, an accurate analysis of major contributors to the cogging component is still difficult to find in past published works. This article aims to address this knowledge gap by identifying the dominant harmonic contents (DHC) responsible for the amplitude of cogging torque. As a result, a new factor is introduced to denote the level of cogging torque, rectifying the defect of the well-known existing factor called the "goodness factor." The correlations between the key parameters (i.e., pole and slot numbers, pole-arc to pole-pitch ratio, and slot-opening to slot-pitch ratio) and the cogging torque are clarified by the proposed methodology. Finally, finite element (FE) and statistical results demonstrate the validity of the proposed results. It is expected that the key findings reported in this article will serve as a valuable reference in the field of electric machines.