Analysis and experimental results of frequency splitting of underwater wireless power transfer

Abstract

Underwater wireless power transfer (UWPT) is an important technique to power underwater devices while its frequency splitting phenomena are not fully elucidated. In this study, frequency splitting phenomena of a symmetrical planar two-coil wireless power transfer (WPT) system resonated at 90 kHz are investigated in seawater and freshwater. A concise frequency splitting analysis of this WPT system in air based on circuit model is given first and then experimental data are reported to show there is little difference between power transfer in air, freshwater and seawater in the range of 40–140 kHz of this WPT system. Consequently, the frequency splitting analysis and observations in air are also applicable in freshwater and seawater. It is found a V-type frequency splitting pattern exists in this WPT system under seawater and freshwater. Frequency shift is observed in this UWPT system in overcoupled region, and no frequency shift is observed in undercoupled region. In undercoupled region, in the low frequency zone of 40–90 kHz the load voltage characteristics in three media are identical; in the high-frequency zone of 90–140 kHz, the load voltage in air is slightly larger than those in freshwater and seawater.

Keywords

• inductive power transmission
• seawater
• V-type frequency splitting pattern
• WPT system
• frequency splitting analysis
• symmetrical planar two-coil wireless power transfer
• frequency splitting phenomena
• UWPT
• underwater wireless power transfer
• frequency splitting
• frequency 40 kHz to 140 kHz
• frequency 40 kHz to 90 kHz