Underwater Wireless Charging System of Unmanned Surface Vehicles with High Power, Large Misalignment Tolerance and Light Weight: Analysis, Design and Optimization
Songyan Niu, Qingyu Zhao, Haibiao Chen, Hang Yu, Shuangxia Niu, Linni Jian
Abstract
Wireless charging systems (WCSs) are considered very appropriate to recharge underwater surface vehicles (USVs) due to their safe, flexible, and cost-effective characteristics. The small depth of immersion of USVs allows a WCS operated at an mm-level distance using a dock. Resultant tight coupling between the transmitter and receiver is conducive to high power, yet faces a challenge to alleviating misalignment sensitivity. In addition, considering USVs’ endurance, the weight of a WCS should be strictly limited. In this paper, a 6.0 kW underwater WCS is analyzed, designed, and optimized, which achieves a good balance of power capacity, misalignment tolerance, and onboard weight. A multi-receiving-coil structure is employed, which is crucial to large misalignment tolerance. On this basis, two types of coils adapting the hull shape of USV, viz., curved and quasi-curved coils, are devised and compared in case the hydrodynamic performance of USV is degraded. Finally, the weight of receiver is effectively reduced using bar-shaped ferrite without sacrificing the power capacity of WCSs. The results indicate a merely 8.73% drop in coupling coefficient with misalignment ranging from 0 to 100 mm. Moreover, ferrite use is reduced by 40.48 kg compared to a ferrite sheet, which accounts for 50.28% weight of the receiver.