A ferrite PM in-wheel motor without rare earth materials for electric city commuters

Kodai Sone, Masatsugu Takemoto, Satoshi Ogasawara, Kenichi Takezaki, Hidekatsu Akiyama

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


Electric city commuters are vehicles used for commuting from suburbs to inner cities and for movement within cities. Because of the short distances that they cover and their small battery size, such vehicles are beginning to attract attention. Generally, a high-performance permanent magnet (PM) composed of rare earth elements, such as neodymium and dysprosium, is used in the in-wheel PM synchronous motor (PMSM) of an electric city commuter. However, rising prices of rare earth elements and export restrictions on them are serious problems. Development of an in-wheel PMSM that does not utilize rare earth PMs is therefore highly desirable for electric city commuter vehicles. Accordingly, our research group has focused on a surface PM type axial gap structure that can achieve a high torque density and a short motor length in the axial direction. The designed motor structure with ferrite PMs replacing the rare earth PMs and the results of a 3-D finite element analysis are introduced in detail in this paper. Moreover, to examine the fundamental characteristics of the designed motor, a prototype is produced and tested.

Original languageEnglish
Article number6332938
Pages (from-to)2961-2964
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number11
Publication statusPublished - 2012
Externally publishedYes


  • Axial gap motor
  • Electric city commuter
  • Ferrite permanent magnet
  • Permanent magnet synchronous motor
  • Surface permanent magnet rotor structure

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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