Underwater Wireless Power Transfer

The feasibility of transferring power over a wide range of distances and orientation offsets has been proven in air for various commercial applications, notably in the electric vehicle industry, by using two loosely-coupled RLC circuits that are tuned to resonate at the same frequency. Key system concepts for resonant wireless power transfer, such as frequency splitting, maximum operating distance, and behavior of the system as it becomes over and under coupled, are well understood theoretically, and demonstrated experimentally. Although prior work on WPT in air is quite extensive and mature, very little research has been conducted on underwater WPT. In particular, no studies have been published describing how basic system concepts vary within a conducting medium such as seawater. In this paper, we report the results of experiments addressing the effects of seawater conductivity on underwater resonant wireless power transfer, compared to the basic system concepts exhibited in air. Results indicate that the losses due to seawater become noticeable for frequencies around 20 kHz, and can be large for frequencies above 50 kHz.