A Misalignment-Tolerant Wireless Charging System for AUVs Using a Balanced Decoupling Coil Set

Inductive power transfer (IPT) technology provides a reliable and flexible solution for energy replenishment of autonomous underwater vehicles (AUVs), but underwater disturbances often cause coupler misalignment and lead to unstable output. This letter proposes a balanced decoupling coil set (BDCS) integrated on the secondary side of a conventional dual coil coupler to realize a symmetric mutual-inductance compensation effect. With this configuration, the misalignment-induced reduction in mutual inductance is effectively compensated, enabling the system to maintain an approximately constant equivalent mutual inductance and stable output characteristics. A 200-W prototype is developed and tested in a seawater environment to validate the effectiveness of the proposed system. Experimental results demonstrate that the system's output voltage and power fluctuations remain within 5% and 10% under normalized offsets of 0.625 and 0.75 along the x- and y-axes, respectively, while achieving a peak efficiency of 90.8%.