Design of coil structure achieving uniform magnetic field distribution for wireless charging platform

Wireless power transfer technology via electromagnetic coupling has been widely used in the planar contactless charging platform. In this paper, a current distribution is deduced to ensure axial component of magnetic field is uniformly distributed in the charging region and zero outside the region. Based on continuous current distributions that can generate even axial component of magnetic field, two transmitting coil structures are proposed. The uniformity of the axial component of magnetic field distribution is confirmed by using the simulation tools. In the case of multiple coils in parallel, the magnetic field distribution near the margin of the charging region changes greatly. This paper analyzed the changes of magnetic field in the case of two coils in parallel, and compared the magnetic field distribution with different coil structures.