Frequency Splitting Analysis of Two-Coil Resonant Wireless Power Transfer

Frequency splitting has been widely observed in resonant wireless power transfer (RWPT). However, there are some misunderstandings concerning this phenomenon in the two-coil RWPT structure. Based on the circuit theory, this letter deduces the expressions of the voltage ratio, the output power, and the efficiency varying with the driving frequency, supplied by a constant ac voltage source. Frequency splitting occurs in the voltage gain and the output power, and the splitting frequency points are deduced. As to the efficiency, no frequency splitting exists, contrary to the current mainstream research. The calculations and the experiments confirm these conclusions.