Design of a SAE Compliant Multicoil Ground Assembly

Inductive power transfer is a technology that enables power to be transferred from a primary (ground assembly) to a secondary (vehicle assembly) without a physical connection. Recommended practice proposed by the SAE J2954 working group has put flux limitations for human exposure in stationary electric vehicle charging applications. The latest version has constrained the leakage flux to 27 μT RMS for EMF limitations. In this article, a new multicoil ground assembly (MCGA) is proposed to reduce the leakage flux. The MCGA can decrease the flux levels by over 25%. All the vehicle assemblies studied can meet the EMF requirements. The ground assembly is the main contributor to leakage flux, except when the DDP WPT3/Z3 secondary vehicle assembly becomes the main contributor. The proposed MCGA is also able to provide similar dc–dc efficiencies compared to the existing Universal Ground Assembly of
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89% at the most misaligned point.