This paper presents design and prototyping studies for coreless and slotless permanent magnet (PM) machines, which have the potential for high power density and efficiency, and discusses their feasibility for electric aircraft propulsion. The emphasis is on axial flux permanent magnet (AFPM) machines with printed circuit board (PCB) stators that have advantages over their wired counterparts in terms of design flexibility, coil accuracy, manufacturing process reliability, and heat dissipation. Detailed electromagnetic finite element analysis models were developed and employed alongside analytical sizing equations to evaluate the performance of two dual-rotor single-stator coreless AFPM designs employing wave and spiral PCB winding patterns. Design considerations for a 10kW 2,600rpm rating similar to the NASA X-57 electric aircraft propulsor motors are included. A 26-pole prototype machine has been developed and experimental testing results are presented.

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Conference Proceeding

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Notes/Citation Information

Published in 2021 IEEE Transportation Electrification Conference & Expo.

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The document available for download is the authors’ manuscript version accepted for publication. The final published version is copyrighted by IEEE and will be available as: D. Lawhorn, P. Han, D. Lewis, Y. Chulaee, and D. M. Ionel, “On the Design of Coreless Permanent Magnet Machines for Electric Aircraft Applications,” ITEC, 2021, 6p.

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Funding Information

The support of the National Aeronautics and Space Administration (NASA) for research on electric aircraft power systems and components through the NASA Grant no. KY GF-20-055 and of the National Science Foundation (NSF) for research on special electric machines and power electronics drives through the NSF Award #
1809876 is gratefully acknowledged. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NASA or the NSF. The support of University of Kentucky, the L. Stanley Pigman Endowment, of ANSYS, Inc., and of Regal Beloit Corp. is also gratefully acknowledged.