Modeling and Implementation of a Long-Distance Seawater Single-Wire CPT System for Underwater Sensor

A long-distance, strong-misalignment tolerance seawater capacitive power transfer(SCPT) system with two insulated electric-field couplers and single-wire for underwater sensors is proposed in this article, and it has the advantages of low cost, low weight and hard worn-out compared with traditional structure. First, quasi electric double layer(Q-EDL) theory for coupler in seawater is proposed, and seawater between two couplers can be considered as equipotential medium is demonstrated in detail. Second, model of seawater electric-field coupled channel is built. The feasibility of long distance and strong misalignment tolerance is proved. Then, double T-LCL compensation network is investigated and selected for constant output voltage, ZPA and anti-frequency-offset. Experimental results in lab show that the system can deliver 732.1W at a dc-dc efficiency of 89.2%. In actual ocean, the experimental transmission distance is 10m, achieving 206.8W power transmission and 83% efficiency, which verifies the proposed program is adapted to power supply of sensors in complex ocean environment and the advantages of long distance. This paper is also accompanied by a video file demonstrating experiment in actual ocean.