Design Of Coil Structure Achieving Uniform Magnetic Field Distribution For Wireless Charging Platform

As the wide use of electric production and the increasing standard of people's life, how to remove the heavy cable and realize the wireless energy transfer became the hot points of research in recent years. The large number of battery operated consumer electronics and the associated tangle of wall-wart chargers has generated interest in designing a single, convenient charging platform. Planar contactless battery charging platform is an emerging technology that has the potential of unifying the charging protocols of portable consumer electronic products.A well-known method of wireless power transmission is the magnetic induction coupling, that is, the primary coil generate time-varying magnetic field, so the voltage induced in receiver coils in order to achieve energy transfer. Inductive charging is an advanced new charging technology which utilizes electromagnetic induction in the coupling to provide a contactless charge coupling to transfer power, and makes up the shortages of the traditional conductive charging.The planar charging platform should be able to charge several electronic devices simultaneously, so the transmitting coil must be large enough to accommodate them, to ensure the uniform power delivery to devices, regardless of position, the axial magnetic field distribution must be even.In this paper, a current distribution is given to ensure magnetic field axial component is uniformly distributed in the charging region and zero outside the region. Based on the this current distribution two transmitting coil structures have been designed. Then we simulated the axial magnetic field distribution on the charging platform, confirmed the uniformity of the field distribution. In the case of multiple coils in parallel, the magnetic field distribution near the edge of the charging region changes because of the edge effect. This paper analyzed the changes in magnetic field in the case of two coils in parallel, and compared the magnetic field distribution with different coil structure.