Analysis of magnetic gearing effect in partitioned stator switched flux PM machines

Z. Z. Wu, Z. Q. Zhu

Research output: Contribution to journalArticlepeer-review

47 Citations (SciVal)


The partitioned stator switched-flux permanent magnet (PM) (SFPM) (PS-SFPM) machine is a novel stator-PM machine in which PMs and armature windings are separately placed in two different stators. Compared with the conventional SFPM machine with a single stator in which both PMs and armature windings are located, the PS-SFPM machine can generate higher torque density due to the utilization of the machine's inner space. In this paper, the magnetic gearing effect in the PS-SFPM machine is investigated in terms of air-gap field harmonics based on a simple magnetomotive force (MMF)-permeance model. It is found that the PS-SFPM machine is one type of magnetically-geared machine, in which the modulations of rotor iron pieces to the open-circuit PM and armature reaction fields are similar to those found in the magnetic gear and the conventional magnetically geared machine. The pole-pair numbers and rotating speeds of the air-gap field harmonics obtained by the MMF-permeance model are verified by finite element (FE) analysis. More than 93% of the average electromagnetic torque is contributed by the main air-gap field harmonics having pole-pair numbers (2i - 1)p PM and Nr,pm, (2i-1)pPM( i = 1,2,3) in a PS-SFPM machine with pPM-pole-pair PMs and Nr-rotor-pole. A prototype machine is fabricated and tested to verify the FE analysis.

Original languageEnglish
Article number7511752
Pages (from-to)1239-1249
Number of pages11
JournalIEEE Transactions on Energy Conversion
Issue number4
Early online date12 Jul 2016
Publication statusPublished - 1 Dec 2016


  • Magnetic gear
  • magnetic gearing effect
  • magnetically-geared machine
  • modulation
  • partitioned stator
  • permanent magnet
  • switched flux

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


Dive into the research topics of 'Analysis of magnetic gearing effect in partitioned stator switched flux PM machines'. Together they form a unique fingerprint.

Cite this