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The study compares the sensitivities of open-circuit airgap flux (OCAF) between a surface-mounted permanent magnet (SPM) machine and a spoke-type PM machine based on variations in airgap length including additional airgaps between permanent magnets and rotor core and between segmented stator cores to achieve high quality electric machines. Analytical equations deduced from magnetic equivalent circuits (MECs) are used to directly compare natural-born characteristics of the OCAF of the two machines. First, the MEC of each machine is modeled by considering two additional airgaps between the PMs and rotor core and between the segmented stator cores. Second, the OCAF equation of each machine is derived from the MEC to analyze the effects of the design variables on the OCAF. Subsequently, the partial derivative equation of the OCAF equation with respect to the airgap length is obtained for sensitivity analysis. A comparison of the equations of the two machines indicates that the spoke-type PM machine exhibits inherently higher sensitivity and average value of the OCAF when compared to that of the SPM machine. Finally, the results are validated via a two-dimensional finite element method (FEM) by considering the variations in airgap lengths.


Jun, C. S., Kwon, O., & Kwon, B. I. (2019). Sensitivity comparison of open-circuit airgap flux between surface-mounted permanent magnet and spoke-type permanent magnet machines considering manufacturing tolerances. IEEE Access, 7, 165908-165918.DOI: 10.1109/ACCESS.2019.2953224

This article is distributed under a Creative Commons Attribution (CC-BY 4.0) License.

This work was supported in part by the BK21PLUS Program through the National Research Foundation of Korea within the Ministry of Education, and in part by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (Ministry of Science) under Grant NRF-2017R1A2B4007697.

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