Oliver Blum

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.

High efficient, compact vehicle power electronics for 22kW inductive charging

This paper presents an automotive suitable power electronics for inductive energy transfer of up to 22kW within a box volume of 3.51. The compact layout and an optimized system topology allow the realization of rectifier and reactive current compensation with a high efficiency of around 98%. The specific layout takes into account cooling of the resonance capacitors as well as of the rectifier. The automotive environment requires failsafe functionality which is independent of the wireless data transfer to the primary side. The hardware is dimensioned and prepared for realizing an additional secondary side power control. Thus, the optimal electrical working point of the energy transfer can be adjusted and overall system losses can be reduced.

7 kW inductive charging: Comparison of circular and bipolar coil topologies

With increasing demand of market and society for locally emission-free transportation, battery electric vehicles have gained significant importance, and an increasing number of passenger cars with increasing range and affordable prices becomes available on the market. One of the main concerns with handling of battery electric vehicles is the charging process. Charging of electric vehicles can be differentiated by use case and charging power. The charging time required for 100 km available range of the electric vehicles decreases with the charging power applied to the vehicle battery.