| With the rapid development of computer,smart power grid,electromagnetic field,the wireless power transmission technology has been deeply researched in recent years and widely used in portable electronic devices,smart household appliances,electric vehicles,the coal mine,underwater environment and other situations.The high transmission power and transmission efficiency can be achieved by the technology of magnetic coupling resonant wireless power transmission in the medium transmission distance.Once it comes out,it has attracted great attention from researchers and businessmen.With the increasingly complex application environment,how to ensure high reliability,high security,high stability,high accuracy while ensuring high transmission efficiency is the problem to be solved urgently.The transmission performance of wireless energy transmission system is studied based on the coupled magnetic resonance technology in this thesis.First of all,the principle of coupled resonance are introduced based on circuit theory,and combine with the two-port network theory,the expressions of S-parameter which can represent transmission performance are deduced.And then the relationship between the transmission performance are deduced with the sending and receiving coils distance,angle offset and horizontal offset.The three-dimensional system simulation model is built by finite element method,the electric field distribution and energy flow of the system are analyzed by vector simulation to find out best antenna orientation.Secondly,studying on the electromagnetic environment problems between multiple wireless power transmission devices,the equivalent circuit model of two systems is built based on the theory of mutual inductance,and then the output power expression is derived.The finite element simulation is used to optimize the calculation process.When the two systems are placed in the coaxial and misplacement position is simulated,the influence of the transmission performance of the system is studied.With the influence of adjacent system on the system,the mutual inductance of the coils is changed,which leads to the frequency splitting of the system and the best resonance point deviation.The best placement of the two systems is found in order to improve the transmission performance through the simulation analysis.In this thesis,the experimental device of low power magnetic coupling resonant wireless power transmission system is designed.The experimental study on the influence of the resonance coil offset and the interaction between the two systems is carried out.The experimental results are in good agreement with the simulation results,which verify the reliability of the theoretical and simulation analysis.Finally,researching on underwater wireless power transmission system,the propagation characteristics of electromagnetic waves in underwater are deduced,and the transmission power and efficiency expressions of the system in underwater environment are obtained.The relationship between transmission performance and transmission distance is studied by the simulation software of Matlab.The energy loss in the seawater medium is analyzed by the multi-physics coupling properties of the Comsol simulation software.The three-dimensional model of human head is established to study the harm of high frequency electromagnetic wave produced by the system to the human body.The influence of seawater temperature and pressure on the transmission performance of the system is studied by analyzing the unstable factors of underwater application environment.The results can provide theoretical support for the development of high performance underwater wireless energy transmission system in the future. |
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