Electromagnetic Field Simulation And Experimental Verification Of Magnetic Coupler Mechanism Of Underwater Wireless Power Transfer

With its extensive ocean area and immense development potential,China has a significant interest in marine resource exploitation.Unmanned underwater vehicles rely on rechargeable batteries as their primary power source,which inevitably leads to limitations in terms of both endurance and range.Wireless power transfer(WPT)technology has emerged as a viable solution for recharging underwater gliders.By facilitating the transfer of energy between the transmitter and receiver without physical contact,WPT technology offers the potential for improved endurance and enhanced stealth capabilities.The magnetic coupler as the key component that enables power transmission,and its optimization can improve the performance of the WPT system underwater.In this study,finite element method was applied to analyze the effect of material and structural parameters of the magnetic coupler on system.This included the selection of conductor material and the soft magnetic material in the magnetic coupler.It has been found that the equivalent internal resistance and system losses can be reduced by using Litz wire in the frequency range of 0-100 k Hz.In addition,it was observed that above a certain threshold,manganese-zinc ferrite and nanocrystalline material had minimal effect on the self-inductance and mutual inductance parameter.Based on these results,a new magnetic coupler was proposed with advantages such as light weight,compact size,good magnetic field convergence,excellent axial rotation resistance,and high operating efficiency.A WPT system was then fabricated to validate the simulation results.Corresponding compensation circuits and power conversion circuits were designed based on the actual parameters of the magnetic coupler and system simulation.The WPT system used an S-S topology compensation network.A full-bridge inverter circuit was used for power conversion at the transmitter,and a full-wave rectifier circuit was used at the receiver.RF communication and frequency/power modulation techniques were used to achieve closed-loop control of the WPT system.The designed circuit of the WPT system enabled stable power transmission at rated power,which met the requirements for performance verification of the magnetic coupler.The WPT system underwent waterproof sealing design and was assembled into an underwater experimental platform with deep-sea oil-filled batteries,loads,and other components.Performance tests on the magnetic coupler were conducted in air,water tank,and ocean environments.In the near-sea conditions,the WPT system prototype achieved a maximum charging power of 1008 W with a peak efficiency of 92.8%.