Basic study on reduction of reflected power using DC/DC converters in wireless power transfer system via magnetic resonant coupling

Nowadays, wireless power transfer via magnetic resonance coupling is researched and developed actively. This method enables power transfer with high efficiency across large air gap and is robust to displacement compared to traditional method. One of the problems for realization of such system is the increase of reflected power due to load variation and displacement. Reflected power will become loss in power source and result in declining efficiency of the power transfer. Therefore, impedance matching circuit becomes crucial for realization of high efficiency wireless power systems. In this paper, a novel method for reduction of reflected power using DC/DC converter is proposed. DC/DC converter operates like variable impedance by changing duty cycle of switching devices and therefore functions as impedance matching circuit. As a basic phase, reduction of reflected power and efficiency improvement by proposed method are investigated by experiment.