Design Considerations for a Self-Latching Coupling Structure of Inductive Power Transfer for Autonomous Underwater Vehicle

Wireless charging to autonomous underwater vehicle effectively prolongs the attended time and extends the endurance mileage. As the most promising underwater power feeding technique, inductive power transfer is also faced with challenges such as the attenuation in seawater, ocean current disturbance, etc. Special concerns in terms of power quality, efficiency improvement, and mechanical fixing need to be considered when designing the underwater electromagnetic coupling structure. An attenuation model in seawater is established in this article. The optimal working frequency range is refined for a specific transmission media. Different from the wireless power transfer system in the air, the underwater WPT system features tight coupling between the transmitter and receiver. The optimal range of coupling coefficient needs to be redesigned, as high coupling coefficient incurs frequency splitting and the increase of harmonic component, while low coupling coefficient results in low efficiency. Based on the theoretical analysis, a self-latching coupling structure is proposed with lightweight design on receiver side. System parameters are optimized correspondingly and a 3-kW experiment validates the theoretical analysis.