Multi-Step Method for Axial-Flux Permanent-Magnet Motor to Reduce Performance Analysis Time

This paper proposes a novel multi-step analysis (MSA) method to reduce the analysis time and improve the accuracy of finite element analysis (FEA) for axial-flux permanent-magnet motors (AFPMM). Unlike the conventional method of performing full-step analysis (FSA) over one period of electrical angle, the MSA accurately derives the average torque and fundamental voltage results by utilizing only the two steps. To validate the performance of the MSA, the analysis accuracy and reduction in analysis time for torque-beta, voltage-beta, and torque-speed curve are compared between the MSA, FSA, and quasi-3D FEA which is another analysis time reduction method across the four cases of pole-slot combinations of yokeless and segmented armature (YASA) type AFPMM. The MSA confirms its overwhelming performance compared to quasi-3D FEA, and compared to FSA, it achieved a maximum error rate of 0.26% for torque-beta, 0.32% for voltage-beta, and 0.30% for torque-speed, along with a 94% reduction in analysis time. Furthermore, the effectiveness of the analysis method is validated through the experimental results of a 20pole-18slot YASA type AFPMM. The proposed analysis method is expected to be widely utilized by motor designers and engineers in the initial design and characteristic curve derivation stages, as it can be universally applied to complex geometries and radial flux permanent magnet motors.