Low-Voltage and High-Current Wireless Power Transfer Systems for Autonomous Underwater Vehicles

Conventional wired charging methods require salvaging autonomous underwater vehicles (AUVs) to the ship for energy replenishment. In addition, the battery voltages are low and the charging currents are high, which may cause large losses and an unbalanced current-sharing issue among the rectifier diodes. A convenient high-current wireless power transfer (WPT) system is introduced for AUV batteries with low voltages to address these issues. In this article, an LCC-S WPT system with a new rectifier is proposed for AUVs. The power transfer capacity, the currents of each component, the power loss analysis, and a detailed design guideline are presented. Because of the high turn ratios of transformers, the high current flows only through diodes, and natural current sharing can be achieved among all rectifiers. This architecture contributes to power improvement and significantly reduces the power loss of the receiving coil without additional BUCK circuits. An LCC-S WPT system with a maximum output power level of 1750 W is built, and experiments are conducted under various working conditions in both air and seawater media. The maximum efficiency in the seawater medium is 88.8% with an output of 24 V/73 A, which proves the feasibility of the system.