Design of Conductive Coupler for Underwater Wireless Power and Data Transfer

Realizing capacitive coupling under seawater is difficult, although the capacitive coupler attracts attention as a promising solution for wireless power and data transfer. The coupler consisting of parallel-plate electrodes (e.g., capacitive coupler) has strong conductive coupling because of the high conductivity of seawater. This study introduces the design of a highly efficient coupler utilizing this phenomenon as a novel method. First, the operational principle of the highly efficient conductive coupler is clarified by comparing it to a conventional conductive coupler. The results reveal the key factor for the high-efficiency design. The design parameters at the maximum available efficiency are derived. The designed coupler is then fabricated. A demonstration shows that the efficiency of over 90% under seawater is achieved at a 20-mm transfer distance and a 1-kW transfer power. The demonstration also shows that power is wirelessly transferred to a camera module via the coupler, with the transferred data recorded by the camera appearing on a laptop computer.