Axial flux PM (AFPM) machines are used particularly in applications requiring a compact structure. Their disc shape topology and axial air-gap have led to a variety of configurations including two popular ones: the yokeless and segmented armature (YASA), and the single-stator single rotor or single sided machine. In this study, a comprehensive comparative analysis of these configurations is conducted at different magnetic and electric loadings. It is found that at lower loadings, typically employed for air-cooled machines, the torque/ampere characteristics of the YASA machine are almost identical to those of a single sided machine constructed with half the magnet volume. On the other hand, the single sided machine outperforms the YASA machine when the magnet volumes in both machines are maintained equal. However, for higher electric loadings, the torque/ampere characteristics of the YASA machine droop significantly less than those of the single sided machine. The paper includes analytical estimations which are verified with experimentally validated FEA simulations. In addition, the impacts of the armature reaction on saturation and the magnetic flux linkage, the magnet losses and eddy current losses in both machines are also explored.

Document Type


Publication Date


Notes/Citation Information

Published in IEEE Transactions on Industry Applications.

© 2020 IEEE Copyright Notice. “Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

The document available for download is the authors’ manuscript version that is accepted for publication. The final published version is copyrighted by IEEE and will be available as: N. Taran, G. Heins, V. Rallabandi, D. Patterson, andD. M. Ionel, “Evaluating the Effects of Electric and Magnetic Loading on the Performance of Single and Double Rotor Axial Flux PM Machines,” IEEE Transactions on Industry Applications, 2020, 10 p.

Digital Object Identifier (DOI)


Funding Information

The support of Regal Beloit Corporation, University of Kentucky, the L. Stanley Pigman endowment and the SPARK program, and ANSYS Inc. is gratefully acknowledged.