Design of resonator for wireless charging system with expanded charging area

This work proposes a novel transmitting and receiving coil structure that can be charged and maintained in efficiency regardless of the position of the transmitting coil on the plane at a certain distance when a transmitting coil having a relatively large area is used as compared with the receiving coil. In generally, the spiral or helical type transmitting coil has a reduced magnetic density as it goes toward the center, so that the rectified voltage and efficiency are decreased at the same time. So the novel structure of transmitting coil and dual receiving coil are proposed in this paper can generate a uniform system efficiency on the charging area, enabling wireless charging regardless of the position of the receiving coil.