Design of an ICPT system for battery charging applied to underwater docking systems

High power consumption limits the endurance of autonomous underwater vehicles (AUVs). It's necessary to build a docking station to recover and recharge AUVs underwater. Inductive coupling is a commonly used method for contactless power transmission, which demonstrates superiorities in an underwater environment. In this study, a pair of coaxial and coreless coil structure is proposed for battery charging of the AUV. The performance of an inductive contactless power transfer (ICPT) system in SP topology is analyzed considering the loss of eddy-current in sea water, switching elements and diode-bridge. An appropriate frequency is selected to realize a maximum system efficiency. In the laboratory experiment, the selected topology demonstrates stable properties and realizes a maximum charging power of approximately 300 W. The efficiency of the ICPT system varies from 75% to 91% with a total efficiency of 63-77% during the entire charging period.