Inductive Wireless Power Transfer for Autonomous Underwater Vehicles: A Review of Coupler Design, Misalignment Challenges, and Eddy Current Loss Mitigation

Autonomous underwater vehicles (AUVs) play a crucial role in oceanographic research, monitoring the environment, and exploring resources in the ocean. Nevertheless, the operational efficiency of these devices is frequently constrained by the limited battery capacity and the requirement for charging while connected to a power source. Wireless power transfer (WPT) offers a non-contact alternative to conventional wet-mate electrical connectors, with inductive coupling receiving particular attention because of its relatively high efficiency, safety, and suitability for underwater charging over short transfer gaps. However, it is limited by the transfer distance, coil misalignment, coupler design constraints, and eddy-current losses caused by conductive seawater. This review assesses the current state of inductive coupling technology with respect to AUVs. It discusses recent advancements in energy sources for AUVs, current technologies for underwater WPT, magnetic coupler design, challenges related to misalignment and their impact on WPT systems, as well as various strategies to mitigate these challenges. The review also covers the analysis and mitigation of eddy current loss and highlights the technical and engineering challenges encountered in power delivery. In general, inductive WPT has significant potential for making AUV charging performance more successful. Experimental studies have indicated efficiencies exceeding 90% in certain controlled situations; however, the literature also demonstrates that performance frequently deteriorates under misalignment and inadequate underwater conditions, which remain major challenges to practical implementation.