Design and Analysis of Inductively Coupled Power Transfer System on Mooring Buoy With Double Ultracapacitor Chargers Using Indirect Control

Inductively coupled power transfer (ICPT) is a new technology used in the mooring buoy for underwater sensors' power supply. In this article, an ICPT system with a mooring cable to power double ultracapacitor chargers is proposed. First, the system model is analyzed in detail, including the primary side of an abovewater system, the mooring cable, and the secondary side of an underwater system. Second, to reduce the torque between the buoy and mooring cable, a noncontact rotary magnetic coupler, which can provide two degrees of freedom, is designed. Third, considering that the charging voltage is difficult to feedback directly, indirect closed-loop control using current in the mooring cable is applied to achieve constant current and voltage charging. Finally, the proposed analyses are verified via experiments. As the gap of the abovewater magnetic coupler changes, two ultracapacitor modules are charged in 1 A, and the maximum efficiency is 65.75%, respectively.