An Axial-Flux Dual-Rotor Slotless Permanent Magnet Motor with Novel Equidirectional Toroidal Winding

Jikai Si, Tianxiang Zhang, Yihua Hu, Chun Gan, Yingsheng Li

Research output: Contribution to journalArticlepeer-review


In this paper, a dual-rotor slotless axial-flux permanent magnet (AFPM) motor with equidirectional toroidal winding (ED-TW) is proposed and compared with the AFPM motor with traditional toroidal winding (T-TW) with the same dimensions, number of coils and poles. Different from the T-TW, only the positive sides of coils of the ED-TW are left on one side of the stator core, the return sides of the coils are all removed to the other side of the stator core. Firstly, the structure and operation principle of the two motors are introduced and analyzed. To clarify the features of the ED-TW, the synthetic electromotive force (EMF) vector and armature reaction field of the ED-TW and T-TW are studied. Secondly, the main size equations of the AFPM motors with toroidal windings are presented. Subsequently, the electromagnetic characteristics of the AFPM motors with ED-TW and T-TW are analyzed and compared based on the three-dimensional finite element method (3D-FEM). The comparison results indicate that the AFPM motor with ED-TW has superiority in torque density and efficiency. Finally, a prototype of the AFPM motor with ED-TW is manufactured and tested, which validates the feasibility of the proposed motor and the correctness of the analysis of the 3D-FEM.

Original languageEnglish
Pages (from-to)1752-1763
Number of pages12
JournalIEEE Transactions on Energy Conversion
Issue number3
Early online date28 Dec 2021
Publication statusPublished - Sept 2022

Bibliographical note

(c) 2021 IEEE. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details


  • Axial-flux permanent magnet motor
  • back-EMF
  • Coils
  • dual rotor
  • electromagnetic characteristics
  • equidirectional toroidal winding
  • Permanent magnet motors
  • Rotors
  • Stator cores
  • Torque
  • torque density
  • Traction motors
  • Windings

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