Frequency Characteristics Analysis of Wireless Power Transfer System in Seawater

Inductively coupled wireless power transfer (ICWPT) has become an effective solution for underwater power transfer. Since there is no direct electrical connection, safety hazards such as cable aging, leakage, and short circuit can be avoided, and the reliability, flexibility, and sealing performance of underwater equipment charging are improved. Although the ICWPT in air has been extensively studied, its transmission characteristics in seawater are still unclear. This paper first discusses the parameter changes when the transmission coil is placed in seawater, then mathematically derives the output characteristics of the series-parallel compensation network, primarily analyzing the system's frequency response. Finally, an experimental platform is built to verify the frequency characteristics of the wireless power transfer (WPT) system in seawater. Frequency splitting and frequency offset phenomena in over coupled regime are analyzed.