Design of an Intrinsically Safe Inductive Charging System Against Offset for Low Voltage Onboard Supply Systems in Lightweight Construction Electrical Vehicles

In the future, mobility will be dominated by different types of e-mobility. Electrical vehicles (EV) equipped with an inductive charging system could gain in comfort and range. EV are mostly equipped with a high voltage battery. Applications with low voltage batteries are of importance for small vehicles, such as electro go-carts. The focus of low voltage batteries has other demands as this of high voltage batteries. An intrinsically safe system with a double-sided Royer-converter and a double-sided parallel compensation is particularly suitable for such cases. The power transfer at a system like this will be stopped automatically when there is a very wide offset between the primary and the secondary coil just as the presence of a short circuit at the secondary side guarantees a safe operation for the total contactless energy transfer system (CET-system). The electronics of the secondary side with this specific circuit topology can be easily considered as an active rectification. Due to this topology only one Royer-converter as a rectifier is to be needed at the secondary side, without any additional electronic monitoring systems. In this paper the development of an inductive charging system as an entire system for a lightweight vehicle with a low voltage battery system will be described. The main focus lies on the selection of most suitable CET-setup and the design of the self-oscillating Royer-converter for the use in the power transfer system. The charging profile will be measured for the complete built up system.