Proposal of Switched-mode Matching Circuit in power supply for wireless power transfer using magnetic resonance coupling

This paper discusses on the matching circuit in the power supply for wireless power transfer using a magnetic resonance coupling (MRC). The MRC is desired to operate at high frequency in the Industry Science Medical (ISM) bands such as 13.56 MHz. The resonance with high quality factor between the transmitting side and receiving side enables high efficiency for wireless power transfer. Therefore, the output frequency of the inverter must be aligned identically to the resonance frequency of the resonance coils in purpose of keeping the high transmission efficiency. In addition, the output impedance of the power supply has to be matched to the characteristic impedance of the transmission line that is despites to the output frequency. In this paper, the Switched-mode Matching Circuit (SMC) which operates to stabilize the output impedance of the inverter is proposed by the authors. The results confirmed in experimental and simulation demonstrates that, the SMC able to provide the variation of the output impedance.