Effective thermal conductivity calculation and measurement of litz wire based on the porous metal materials structure

Xiaomei Liu, David Gerada, Zeyuan Xu, Martin Corfield, Chris Gerada, Haitao Yu

Research output: Journal PublicationArticlepeer-review

32 Citations (Scopus)


Litz wires are employed in high-frequency electrical machines due to their advantages of reducing the ac losses, including minimizing the skin effect and the proximity effect. In order to improve the reliability of such machines, and enable accurate thermal predictions at the design stage, accurate calculation of the thermal conductivity of litz wire is important. In this paper, a calculation method based on the Gasar porous metal materials model is put forward. In this method, a cell model is extracted from the litz wire, and a thermal resistance network is used to calculate the equivalent thermal conductivity (ETC). Following this, two finite-element analysis (FEA) models for the same litz wire are built, one with actual thermal conductivities for the different constituent materials and another with the calculated equivalent thermal conductivity for an equivalent material, with the two models showing similar thermal characteristics. Finally, an experimental setup is built for measuring the steady-state ETC of litz wire. The apparatus structure and characteristics are described in detail, and the experiment uncertainty and measurement errors are analyzed. Three types of litz wire are measured in the experimental, and the results from experiment and calculation are consistent.

Original languageEnglish
Article number8693694
Pages (from-to)2667-2677
Number of pages11
JournalIEEE Transactions on Industrial Electronics
Issue number4
Publication statusPublished - Apr 2020


  • Equivalent thermal conductivity (ETC)
  • Gasar porous metal materials (GPMM)
  • litz wire
  • measurement

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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