Copper foil windings for WPT systems

Wireless power transfer (WPT) is a promising technology for charging electric vehicles (EVs) as it is convenient, and less sensitive to the environmental conditions. Usually charging coils (pads) of WPT based EV charging systems are made of Litz wire, making coils bulky and expensive with relatively high copper losses. This paper investigates the use of copper foil based pad designs for WPT systems to reduce both the cost and losses. A comparison of Litz wire based and copper foil based pads is presented in terms of flux distribution and coupling performance. A new curved shaped copper foil design is also proposed, presenting results in comparison to a simple copper foil pad design. Both simulated and experimental results suggest that the losses can be reduced significantly by the proposed curved copper foil coil design.