Maximum Available Power of Undersea Capacitive Coupling in a Wireless Power Transfer System

This paper studies the maximum available power of a dissipative capacitive power transfer (CPT) system submerged in seawater. The CPT system's maximum power capability is driven using the network theory, precisely the conjugate-image approach. The equations of the maximum available load power and the system's corresponding efficiency are expressed as a function of the capacitive coupling parameters. The experimental results demonstrate that the maximum available power and the corresponding efficiency decreases by a maximum of 10%, which occurs at 1.4 $\mathrm{M}\mathrm{H}\mathrm{z}$, when the plates' separation distance change from 100 mm to 300 mm. Besides, the system has higher power transfer capability and higher efficiency at a low-frequency range than a high one. The maximum available load power decreases by about 22.5% when increasing the frequency from 300 $\mathrm{k}\mathrm{H}\mathrm{z}$ to 1.4 $\mathrm{M}\mathrm{H}\mathrm{z}$. Thus, the CPT system can provide a good solution to charge electric ships and underwater vehicles over a wide separation distance and low-frequency range.