Multi-Physics Field Coupling Modeling and Thermal Distribution Analysis of Underwater Rotary Magnetic Coupling Mechanism

The underwater wireless power transfer (WPT) technology provides an effective solution to underwater energy transfer without direct electric contact, and the underwater electromagnetic coupler (UEC) of the WPT system is a critical component in realizing the technology. This article introduces a novel secondary rotary banner UEC structure that meets the high efficiency and reliability requirements for wireless charging of autonomous underwater vehicles (AUVs), while providing the benefits, such as low-temperature rise, easy charging alignment, lightweight design, and strong offset resistance. Based on the strong relationship between the UEC’s temperature rise and the reliability of the underwater WPT system, electromagnetic-thermal-fluid multi-physics coupling simulation models are established for three secondary rotary UECs to compare different secondary-side structures, effectively addressing the challenges of estimating the temperature distribution related to uneven power losses. To further realize accurate calculation of the thermal distribution, the effects of seawater eddies, seawater heat exchange, and the shell are considered. The simulation and experimental results show that the comprehensive performance index of the secondary full-banner UEC is superior, and the temperature rise distribution of the established physical model can be used to accurately predict the actual situation. The maximum error between simulation and practical measurement is 2.45%, which verifies these models, and provides a theoretical basis for improved heat dissipation design of the UEC.