Research On Underwater Magnetically Coupled Resonant Wireless Energy Efficient Transmission Technology

With the survey,development,and utilization of the ocean more and more attention by the country,many marine detection instruments are placed in the sea.Due to the fluidity and instability of the seawater,the traditional battery power supply is limited by the battery capacity and power.Wired power supply using wet-plug power transmission technology is subject to safety hazards,high price,short service life,and other factors.It is challenging to support high-density and high-intensity marine scientific research in the future for a long time.The application of wireless energy transmission technology in the seawater environment will effectively reduce the instrument's human resources or material cost caused by energy supply problems and improve the endurance and operation efficiency of the detection instrument.This paper is based on the application of magnetically coupled resonance wireless energy transfer in the marine environment.The electromagnetic model is analyzed for the eddy current loss caused by seawater conductivity in terms of the theoretical model.A series compensation model for seawater equivalent circuit loss is proposed—transmission characteristics of the transmission system.At the same time,an energy transmission prototype of the underwater magnetic coupling system was built,the hardwired connection of the prototype was given,and the magnetic field and eddy current distribution in seawater were simulated by the finite element electromagnetic method.Finally,the transmission of the system was analyzed through experiments.And verify the feasibility of the loss model.The experimental results show that the underwater magnetic coupling energy transmission efficiency can reach 72.6%,which is roughly the same as the air transmission efficiency,and its output power is 12.68 W.With the analysis of the eddy current loss of seawater,it is further found that the eddy current is mainly affected by the seawater conductivity.Then,the influence of the conductivity of seawater on the transmission performance of the system is explored,and a method for measuring the conductivity of seawater based on magnetically coupled resonance is proposed.The method of measuring magnetic coupling resonance seawater conductivity is to analyze the relationship between the transmission loss of the resonant magnetic field and the seawater conductivity.The field is between the transceiver coils in seawater.This paper by analyzing the principle of magnetic coupling resonance measurement.The circuit model of the magnetic coupling resonance measurement system applied in seawater is established.The experimental device is set up for laboratory tests,and the corresponding test situation is simulated by finite element electromagnetic.The test and simulation results show that the measurement principle is feasible.The system has the best measurement performance at the resonant frequency,especially for low conductivity conditions,and has better sensitivity.With the resonant frequency increase,the measurement system has a better response to seawater conductance.The resolution of the rate will increase.The seawater conductivity measurement method this paper explores provides a novel theoretical approach and technical support for measuring low conductivity solutions.