Effective Thermal Conductivity Calculation and Measurement of Litz Wire based on the Porous Metal Materials Structure

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

Abstract

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.

Citation

Liu, X., Gerada, D., Xu, Z., Corfield, M., Gerada, C., & Yu, H. (2020). Effective Thermal Conductivity Calculation and Measurement of Litz Wire based on the Porous Metal Materials Structure. IEEE Transactions on Industrial Electronics, 67(4), 2667-2677. https://doi.org/10.1109/tie.2019.2910031

• Journal Article Type: Article
• Acceptance Date: Apr 10, 2019
• Online Publication Date: Apr 17, 2019
• Publication Date: 2020-04
• Deposit Date: Apr 7, 2020
• Publicly Available Date: Apr 7, 2020
• Journal: IEEE Transactions on Industrial Electronics
• Print ISSN: 0278-0046
• Electronic ISSN: 1557-9948
• Publisher: Institute of Electrical and Electronics Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 67
• Issue: 4
• Pages: 2667-2677
• DOI: https://doi.org/10.1109/tie.2019.2910031
• Keywords: Control and Systems Engineering; Electrical and Electronic Engineering
• Public URL: https://nottingham-repository.worktribe.com/output/3236465
• Publisher URL: https://ieeexplore.ieee.org/document/8693694
• Additional Information: © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.