Modeling and effects of in situ magnetization of isotropic ferrite magnet motors

Min Fu Hsieh, David G. Dorrell, Ching Kuo Lin, Po Ting Chen, Peter Y.P. Wung

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


This paper outlines a method using finite-element analysis (FEA) to model the magnetization process of a small brushless surface-magnet three-phase motor with isotropic ferrite magnets and concentrated windings. This is aimed at allowing in situ magnetization using the three-phase machine winding. Radial magnetization is the nominal manufactured magnetization pattern; however, the in situ method leads to a variation in the magnetization pattern, and the performance is examined using open-circuit simulations. The properties of the magnet material (a ferrite 5 type) are examined in order to simulate the magnetization. Bulk magnetization $H-{{\rm s}\hbox{-}{\rm sat}}$ levels for ferrite type 5 indicate that a 10-kOe field is required. In this paper, localized magnetization is examined using FEA, and it is measured in actual rotors by examination of the surface flux density when removed from the stator. Methods for deriving the approximate back electromotive force from both the FEA and the surface measurements are put forward; these show a reasonable correlation. The use of magnetization functions allows the magnetization pattern to be applied to the simulations. This paper uses a standard manufactured machine to carry these out. Open-circuit experiments are conducted to validate the presented method.

Original languageEnglish
Article number6548064
Pages (from-to)364-374
Number of pages11
JournalIEEE Transactions on Industry Applications
Issue number1
Publication statusPublished - 2014 Jan 1

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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