Encapsulation Residual Stress and Ferrite Loss in Inductive Coil Assemblies

Conference · Sun Oct 01 04:00:00 EDT 2023

DOI:https://doi.org/10.1109/ECCE53617.2023.10362318· OSTI ID:2283846

Foote, Andrew ^[1]; Costinett, Daniel ^[1]; Henken, William ^[2]; Kusch, Ruediger ^[3]; Mohammad, Mostak ^[1]; Onar, Omer ^[1]

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1. ORNL
2. Volkswagen Group of America
3. Volkswagen

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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 2283846
• Country of Publication: United States
• Language: English