Mitigating Interturn Parasitic Losses in Underwater WPT Systems via Compensation Relocation and Electric Field Shaping

In underwater wireless power transfer (WPT) systems, parasitic losses from inter-turn parasitic capacitance, exacerbated by water’s conductivity and high permittivity, present a significant but often-overlooked challenge. This letter addresses this gap by first analyzing these inter-turn losses and their distribution within the insulator-water composite medium of underwater coils. An equivalent model capturing these effects is subsequently developed. Then, to actively suppress these losses without additional components, a novel method that strategically relocates the compensation capacitors is proposed. This relocation reshapes the electric field distribution across the coils, thereby enhancing system efficiency. Experimental results from a 1.3 kW prototype validate the proposed method, demonstrating a 1.35% efficiency improvement over conventional compensation and achieving a peak efficiency of 92.23%.