Insulated Coupler Structure Design for the Long-Distance Freshwater Capacitive Power Transfer

This article proposes a long-distance capacitive power transfer (CPT) system in the freshwater environment. The theoretical model of the capacitive coupler is derived in the freshwater scenario, considering the impact of the insulation. The finite element analysis by high-frequency structure simulator (HFSS) is used to simulate the coupler structure. Compared with the system in air, the coupling capacitance in a freshwater system is less sensitive to the distance variation. The transfer distance is therefore significantly extended in the freshwater environment. Then, a prototype is implemented to validate the analysis, in which the plate length is 200 mm. In the freshwater testing, experiments show that the system achieves 219.6 W output power across a distance of 500 mm with the efficiency of 60.17%. When the misalignment is 100 mm, the variation of output power is within 3.3%, and the efficiency is still maintained at 54.9%. When the transfer distance is 350 mm, the system efficiency is 69.0%. Therefore, the experimental results validate that the proposed long-distance CPT system is achieved in the freshwater environment.