Coil Scaling Law of Wireless Power Transfer Systems for Electromagnetic Field Leakage Evaluation for Electric Vehicles

Abstract

Wireless power transfer (WPT) systems have receieved considerable interest for promoting the sale of electric vehicles (EVs). In order to increase the use of WPT systems, electromagnetic field (EMF) leakage should be evaluated at neighborhood and faraway points. Generally, these are measured in the shield room. However, systems that use many coils and cores require very large shield rooms, and accurate measurements are difficult to obtain. In this study, we investigate the coil scaling law to simplify EMF evaluation. Satisfied conditions that enable an equivalent evaluation between full-scale coils and mini-scale ones are derived. The effectiveness of this method is demonstrated using by simulations and experiments.