Design and evaluation of a variable-flux flux-intensifying interior permanent-magnet machine

Natee Limsuwan, Takashi Kato, Kan Akatsu, Robert D. Lorenz

Research output: Contribution to journalArticlepeer-review

178 Citations (Scopus)


This paper presents a design approach for interior permanent-magnet (IPM) machines with variable-flux characteristics using low-coercive-force magnets for improved efficiency and extended operating speed range. A flux-intensifying IPM type with Ld > Lq is used in the design due to positive Id operation and reduced loaded Iq effects. Design considerations of machine structures and variable-flux machine attributes are discussed. In addition, leakage flux in a rotor is particularly designed to also obtain another flux-varying capability. Evaluation of the designed machine is provided by finite-element analysis simulations and experiments on a proof-of-principle machine. The designed machine shows benefits in increasing efficiency and speed range in a low-torque region when variable magnetization control of the low-coercive-force magnets or the design of the leakage flux proposed in this paper is implemented.

Original languageEnglish
Article number6560407
Pages (from-to)1015-1024
Number of pages10
JournalIEEE Transactions on Industry Applications
Issue number2
Publication statusPublished - 2014


  • Flux intensifying
  • interior permanent magnet (IPM)
  • low-coercive-force magnet
  • machine design
  • variable-flux linkage

ASJC Scopus subject areas

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


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