Efficiency Improvement in Dynamic Wireless Power Transfer by Placing a Magnetic Sheet Under the Power Transmitting Coil

Electric vehicles have a short driving range and require long charging times. Wireless power transfer (WPT) during vehicle moving can extend the driving range of such vehicles. In WPT for stationary vehicles, ferrite cores are used in the back yoke to improve power transfer efficiency. However, issues associated with the high cost, durability, and excessive weight can emerge when installing ferrite coils on roads. As a result, ferrite is not used in the back yoke of the transmitting side during WPT for moving vehicles. In this study, we propose a lightweight and flexible magnetic sheet made of a magnetic composite material. This sheet can be placed under the transmitting coil. In this way, the coil Q factor and coupling coefficient can be improved. In this study, we report the improvement in transmission efficiency when the receiving coil moves and consequently, the improvement in the overall transfer efficiency of the power supply section.