Design Method of Coreless Coil Considering Power, Efficiency and Magnetic Field Leakage in Wireless Power Transfer

Abstract

Dynamic wireless power transfer to electric vehicles is attracting a great deal of attention as a solution to current battery EV issues and a contribution to decarbonization. While there are many challenges for social implementation, the selection of appropriate coils is another important topic. Coils must take into account not only transmission power and efficiency, but also safety, particularly with regard to leakage magnetic fields. In this study, all electrical characteristics of coils were obtained from theoretical equations and compared with electromagnetic field analysis, which showed good agreement. It was found that even a coreless coil can transmit 15.6 kW, 99.1% of the power, below the regulated value of the magnetic field strength. The effects of coil pitch, size, and input voltage on the magnetic field strength are also shown.