A New Rotor Structure for High Speed Flywheel Permanent Magnet Synchronous Machine

Zichong Zhu, Yunkai Huang, Jianning Dong, Fei Peng

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
33 Downloads (Pure)


This paper presents a new rotor design with assembled permeable retaining sleeve (APRS) to improve performances of a high speed permanent magnet synchronous machine (PMSM). The APRS consists of equal number of permeable and nonmagnetic parts, which are alternately arranged and assembled together circumferentially via keyways. Electromagnetic and mechanical characteristics of the rotor applied to a high speed flywheel PMSM are analyzed using finite element method. Machine performances are compared to an original design with commonly used rotor structure. It shows that phase inductance of the high speed machine increases dramatically due to smaller effective air gap, which may benefit suppressing inverter current harmonics. Also, permanent magnet usage reduces by 9.4 % to obtain identical back electromotive force and torque constant. In addition, a smaller skin depth owing to high-permeability material and the circumferential segmentation of the retaining sleeve effectively reduce rotor eddy current. Associated loss decreases by 40.7 % under open-circuit condition. A prototype rotor is fabricated and preliminary experimental tests are performed to confirm the analysis results.
Original languageEnglish
Pages (from-to)463-470
Number of pages8
JournalJournal of Magnetics
Issue number3
Publication statusPublished - Sept 2019

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


  • high speed machine
  • permeable
  • permanent magnet usage
  • retaining sleeve
  • rotor eddy current loss


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