Wireless Power transfer (WPT) has been applied to the design of auxiliary power supplies for medium voltage semiconductor devices due to its strong isolation capability. However, insulation characteristics of WPT coils are not clear under the high voltage stress, especially when the ferrite layer is added. This paper takes advantage of Finite Element Analysis (FEA) and clarifies the major differences between two-dimensional and three-dimensional WPT coil models. Then, insulation characteristics of the WPT coils in terms of the electric field distribution and the maximum electric field are studied under different voltage levels and transfer distances. The influence of applying the ferrite layer is also considered and an optimal magnetic shielding layer design method is proposed. Finally, the effect of the ferrite shielding layer to WPT coils on suppressing electromagnetic interference is analyzed.

high-voltage power supply;wireless power transfer;finite element analysis;ferrite shielding layer