A Wideband Strongly Coupled Magnetic Resonance Wireless Power Transfer System and Its Circuit Analysis

Conventional strongly coupled magnetic resonance (SCMR) wireless power transfer (WPT) systems have high quality factor (Q), leading to limited system bandwidths. In practical applications, especially in human-involved environments, the resonant frequency of SCMR resonators will shift due to the effect of highly dielectric human body. In this letter, a wideband four-coil SCMR WPT system is proposed by improving the coupling between the tx/rx coil and their corresponding resonators. The bandwidth is increased by over 100% compared to a conventional system without sacrificing the efficiency much. The wideband feature is demonstrated by both simulation and measurement. It is analyzed physically and by using an equivalent circuit analysis.