Compact 7 kW inductive charging system with circular coil design

A compact 7 kW inductive charging system for current automotive requirements is presented. The system is designed with the purpose of low hardware effort. Magnetic design incorporates asymmetric circular planar coils with a minimum of active materials. A new power electronics topology has been realized with dual-side power control that also uses minimum active and passive components and yields superior performance over a wide range of operational parameters. A position tolerance of > 150 mm in transversal and > 75 mm in longitudinal direction is demonstrated. Overall DC-to-DC efficiency is > 86 % for even worst coupling conditions. Due to low magnetic coupling factors, power losses are dominated by the transformer losses, which can be improved by an advanced magnetic design. The system is ready for bidirectional power transfer, enabling future vehicle-to-grid and smart home applications.