Three-Dimensional Multi-Transmitting Coil With High Isolation for Spatial Wireless Charging

Research for securing the degree of spatial freedom of the receiver in a wireless power transfer (WPT) system has been steadily conducted. In this paper, a study was conducted to improve the power transmission efficiency (PTE) by securing the isolation between transmitting coils in a three-dimensional (3D) multi-coil system for the spatial freedom of the receiver. The optimal overlap interval was derived by analyzing the mutual inductance between coils using a simple overlapping structure between single coils. The isolation of the proposed multi-transmitting coil was significantly improved to less than -30dB. In addition, it was proved through experiments that the PTE is improved using the proposed high isolation transmitting coil. Using this high-isolation multi-WPT system, the PTE of more than 40% was achieved for the height and angle misalignment of the receiving coil by reducing the loss caused by mutual coupling between transmitting coils.