Frequency Decrease Analysis of Resonant Wireless Power Transfer

TLDR

Resonant wireless power transfer has rapidly advanced, operating at higher frequencies than conventional inductive transfer, and its efficiency depends on the transfer quality factor and load matching. The study proposes and implements two solutions to lower the resonant frequency without sacrificing efficiency at fixed distances. The authors analyze two fundamental RWPT structures, derive efficiency formulas, and implement two solutions to lower frequency while preserving efficiency. Theoretical and experimental results confirm that the resonant frequency can be reduced while maintaining efficiency.

Abstract

Recent years have witnessed the booming development of resonant wireless power transfer (RWPT). Compared with conventional inductive power transfer, the frequency of RWPT is usually much higher. To reduce the resonant frequency while maintaining the transfer efficiency constant at the same transfer distances, two solutions are proposed and realized in this letter. Two fundamental structures for RWPT are analyzed and the expressions of the transfer efficiency are deduced. It is pointed out that the transfer quality factor and the load matching factor are two important factors of achieving high transfer efficiency. The larger the transfer quality factor, the higher the transfer efficiency. There is an optimal load matching factor to reach the highest transfer efficiency. The transfer efficiency can remain constant at the same distances if the transfer quality factor is kept at the same level and the load is matched. Theoretical calculations and experimental results provide a sound basis for decreasing frequency.