Impact of Encapsulation on the Core Loss of Ferrites in Inductive Power Transfer

Inductive power transfer (IPT) magnetics are often “potted” with an encapsulant material to improve thermal performance. Mismatched thermal expansion of the encapsulation and magnetic core materials creates a residual mechanical stress that permanently reduces the magnetic perf...

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Bibliographic Details
Main Authors: Alexander K. Bailey, Willsen Wijaya, Seho Kim, Jerry Sun, Tom Allen, Grant A. Covic
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Open Journal of Power Electronics
Subjects:
Online Access:https://ieeexplore.ieee.org/document/11060834/
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Summary:Inductive power transfer (IPT) magnetics are often &#x201C;potted&#x201D; with an encapsulant material to improve thermal performance. Mismatched thermal expansion of the encapsulation and magnetic core materials creates a residual mechanical stress that permanently reduces the magnetic performance of the Mn&#x2013;Zn ferrite core layer. An encapsulated small-scale Double-D IPT pad designed for <inline-formula><tex-math notation="LaTeX">$\mathrm{2.5}$</tex-math></inline-formula> <inline-formula><tex-math notation="LaTeX">$\mathrm{kW}$</tex-math></inline-formula> is built and tested, and the core loss of the ferrite tiles increases by <inline-formula><tex-math notation="LaTeX">$\mathrm{121}$</tex-math></inline-formula>% after encapsulation with a polyurethane-based material. The change in the core loss of the potted IPT pad after encapsulation is predicted using finite element analysis, and the proposed method matches within <inline-formula><tex-math notation="LaTeX">$\mathrm{7.3}$</tex-math></inline-formula>% . Three methods are presented to mitigate this increase in losses and experimentally verified on ferrite toroids. These results show that the choice of encapsulation material significantly impacts the thermal, structural, and electromagnetic behavior of the IPT pad.
ISSN:2644-1314