A thermal improvement technique for the phase windings of electrical machines

Michael Galea, Chris Gerada, Tsarafidy Raminosoa, Patrick Wheeler

Research output: Journal PublicationArticlepeer-review

152 Citations (Scopus)


In electrical machines, a higher torque/force density can usually be achieved by increasing the current density in the windings. However, the resulting increase in copper losses leads to higher temperatures in the coils, particularly in the center of the slots where the thermal resistance to the ambient/cooling surfaces is highest. In this paper, a novel, simple technique is presented in which a higher thermal conductivity path between the center of the slot and the cooling arrangement is created, thus increasing the heat flow away from the slot center. A lumped-parameter thermal model is presented and used along with finite-element analysis to investigate the effectiveness of the proposed technique. The lumped-parameter model is also used for optimizing the high conductivity path for maximum air-gap shear stress and to obtain a compromise between the reduced slot area and the improved temperature distribution. Experimental validation is then presented to compare the predicted results with the measured results on a purposely built instrumented setup.

Original languageEnglish
Article number6074939
Pages (from-to)79-87
Number of pages9
JournalIEEE Transactions on Industry Applications
Issue number1
Publication statusPublished - Jan 2012
Externally publishedYes


  • Electrical machine windings
  • high current density
  • permanent-magnet machines
  • thermal improvements

ASJC Scopus subject areas

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


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