Improvement in Efficiency of Underwater Wireless Power Transfer with Electric Coupling

Yasumasa NAKA  Kyohei YAMAMOTO  Takuma NAKATA  Masaya TAMURA  

IEICE TRANSACTIONS on Electronics   Vol.E100-C   No.10   pp.850-857
Publication Date: 2017/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E100.C.850
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technology)
underwater wireless power transfer,  electric coupling,  maximum available efficiency,  kQ product,  dielectric loss,  

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This paper focuses on underwater wireless power transfer with electric coupling. First, the maximum available efficiency is derived by using the S-parameters of the parallel plate coupler. The frequency which represents the maximal value of the efficiency is revealed. Further, the elevation in the efficiency in association with a reduction of the electrode size is found. It is clarified that the elevation depends on the characteristic of the water dielectric loss. From these results, the optimal electrode size that obtains the maximal value of the efficiency is provided. Finally, we fabricate the couplers by utilizing the optimal frequency and the electrode size. The efficiency of 75.8% under water is achieved.