Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies

Andrew Foote; Daniel Costinett; William Henken; Ruediger Kusch; Mostak Mohammad; Omer Onar

doi:10.1109/ECCE53617.2023.10362318

Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies

Andrew Foote, Daniel Costinett, William Henken, Ruediger Kusch, Mostak Mohammad, Omer Onar

Vehicle Power Electronics Research

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

5 Scopus citations

Abstract

As inductive wireless charging reaches higher power levels, thermal management and mechanical durability become more critical. To address these concerns, past works have demonstrated the benefit of encapsulating coil assemblies in thermally conductive materials. However, due to the sensitivity of the MnZn ferrites commonly used in coil assemblies to mechanical stress, care must be taken to avoid creating large stresses in the ferrite that cause higher hysteresis loss. The stress formation in the encapsulant curing process is overviewed and modeled and an experiment is performed to demonstrate the effect in a small-scale coil assembly. Finally, the effect is shown in the reduced coil-coil efficiency of a first generation high power inductive power transfer prototype using a stiff epoxy compared to better performance in a second prototype using a softer thermally-conductive silicone encapsulant.

Original language	English
Title of host publication	2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023
Publisher	Institute of Electrical and Electronics Engineers Inc.
Pages	1843-1850
Number of pages	8
ISBN (Electronic)	9798350316445
DOIs	https://doi.org/10.1109/ECCE53617.2023.10362318
State	Published - 2023
Event	2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023 - Nashville, United States Duration: Oct 29 2023 → Nov 2 2023

Publication series

Name	2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023

Conference

Conference	2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023
Country/Territory	United States
City	Nashville
Period	10/29/23 → 11/2/23

Funding

This manuscript has been co-authored by Oak Ridge National Laboratory, operated by UT Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to the results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public access-plan). This work made use of the Engineering Research Center Shared Facilities supported by the Engineering Research Center Program of the National Science Foundation and DOE under NSF Award Number EEC-1041877 and the CURENT Industry Partnership Program. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation. This work was funded by Volkswagen Group Innovation in collaboration with the CURENT Engineering Research Center at the University of Tennessee, Knoxville and the Power Electronics and Electric Machinery Research Center at Oak Ridge National Laboratory.

Keywords

coil design
compressive stress
encapsulation
inductive power transmission
magnetic materials
wireless power transfer

Access to Document

10.1109/ECCE53617.2023.10362318

Cite this

Foote, A., Costinett, D., Henken, W., Kusch, R., Mohammad, M., & Onar, O. (2023). Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies. In 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023 (pp. 1843-1850). (2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ECCE53617.2023.10362318

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title = "Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies",

abstract = "As inductive wireless charging reaches higher power levels, thermal management and mechanical durability become more critical. To address these concerns, past works have demonstrated the benefit of encapsulating coil assemblies in thermally conductive materials. However, due to the sensitivity of the MnZn ferrites commonly used in coil assemblies to mechanical stress, care must be taken to avoid creating large stresses in the ferrite that cause higher hysteresis loss. The stress formation in the encapsulant curing process is overviewed and modeled and an experiment is performed to demonstrate the effect in a small-scale coil assembly. Finally, the effect is shown in the reduced coil-coil efficiency of a first generation high power inductive power transfer prototype using a stiff epoxy compared to better performance in a second prototype using a softer thermally-conductive silicone encapsulant.",

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Foote, A, Costinett, D, Henken, W, Kusch, R, Mohammad, M & Onar, O 2023, Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies. in 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Institute of Electrical and Electronics Engineers Inc., pp. 1843-1850, 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Nashville, United States, 10/29/23. https://doi.org/10.1109/ECCE53617.2023.10362318

Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies. / Foote, Andrew; Costinett, Daniel; Henken, William et al.
2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. Institute of Electrical and Electronics Engineers Inc., 2023. p. 1843-1850 (2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

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AU - Foote, Andrew

AU - Costinett, Daniel

AU - Henken, William

AU - Kusch, Ruediger

AU - Mohammad, Mostak

AU - Onar, Omer

PY - 2023

Y1 - 2023

N2 - As inductive wireless charging reaches higher power levels, thermal management and mechanical durability become more critical. To address these concerns, past works have demonstrated the benefit of encapsulating coil assemblies in thermally conductive materials. However, due to the sensitivity of the MnZn ferrites commonly used in coil assemblies to mechanical stress, care must be taken to avoid creating large stresses in the ferrite that cause higher hysteresis loss. The stress formation in the encapsulant curing process is overviewed and modeled and an experiment is performed to demonstrate the effect in a small-scale coil assembly. Finally, the effect is shown in the reduced coil-coil efficiency of a first generation high power inductive power transfer prototype using a stiff epoxy compared to better performance in a second prototype using a softer thermally-conductive silicone encapsulant.

AB - As inductive wireless charging reaches higher power levels, thermal management and mechanical durability become more critical. To address these concerns, past works have demonstrated the benefit of encapsulating coil assemblies in thermally conductive materials. However, due to the sensitivity of the MnZn ferrites commonly used in coil assemblies to mechanical stress, care must be taken to avoid creating large stresses in the ferrite that cause higher hysteresis loss. The stress formation in the encapsulant curing process is overviewed and modeled and an experiment is performed to demonstrate the effect in a small-scale coil assembly. Finally, the effect is shown in the reduced coil-coil efficiency of a first generation high power inductive power transfer prototype using a stiff epoxy compared to better performance in a second prototype using a softer thermally-conductive silicone encapsulant.

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KW - inductive power transmission

KW - magnetic materials

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Foote A, Costinett D, Henken W, Kusch R, Mohammad M , Onar O. Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies. In 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023. Institute of Electrical and Electronics Engineers Inc. 2023. p. 1843-1850. (2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023). doi: 10.1109/ECCE53617.2023.10362318

Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies

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