A Self-Oscillating Underwater Wireless Charging System With Flexible Load Configuration and Misalignment Tolerance for AUVs

As ocean exploration expands, underwater wireless charging systems are increasingly required to support multiple autonomous underwater vehicles (AUVs), thereby improving overall mission efficiency. However, seawater disturbances may induce complex interload misalignments that degrade charging stability. This article proposes a self-oscillating underwater wireless charging system for AUVs with flexible load configuration, enabling stable and balanced power transfer under both single-load and dual-load conditions. Circuit models are established for the two operating modes, and the corresponding output characteristics are derived. Three indices are defined to evaluate output-voltage stability, balance, and consistency under variations in coupling conditions, loads, and operating modes. A parameter design procedure is developed to determine the inductance distribution coefficient. A 220 W prototype is built and tested in saline water, achieving a peak DC-DC efficiency of 90.4%. Experimental results show that, in most tested cases with load variations and misalignment-induced coupling-coefficient variations of up to 25%, the output-voltage variation in both operating modes remains within 10%. Under dual-load operation, the interload voltage difference remains within 10%, and the deviation between the single-load and dual-load output voltages is approximately 3%.