| Wireless charging technology has broad application prospects because of its security,reliability,flexibility and other advantages.Magnetic coupler is the core component of wireless charging system,which consists of energy transmitting coil,energy receiving coil and corresponding shielding layer.At present,in order to improve the coupling performance of the system and reduce electromagnetic leakage,a large number of ferrite cores and aluminum materials are used in the electromagnetic shielding layer of magnetic couplers at present,which causes the problems of large volume,large weight and high cost of magnetic couplers,and restricts the promotion of wireless charging technology.To solve the above problems,this thesis studies the coupling characteristics and magnetic field distribution characteristics of the magnetic coupler,proposes a new double-layer shield structure and a new three-layer shield structure,and optimizes the structural parameters with the help of finite element simulation software.In the end,the experiment for verification is done.The specific work is as follows:The optimization design principle of magnetic coupler is analyzed.The circuit model of wireless charging system is established,and the influence of magnetic coupler parameters on system efficiency is analyzed,which points out the direction of optimization of magnetic coupler.The magnetic circuit of the magnetic coupler is analyzed and the magnetic circuit equivalent model is established to lay a theoretical foundation for the optimization of magnetic core structure.This thesis introduces the common methods and shielding materials of electromagnetic shielding,and analyzes the principles of magnetic and conductive shielding in detail,which provide theoretical support for the optimization of electromagnetic shielding layer structure.The magnetic coupler is optimized.This thesis optimizes each component of magnetic coupler based on 3D finite element simulation software.In this thesis,the coil structure of magnetic coupler is studied,and the coupling characteristics,magnetic field distribution and anti-offset ability of single coil and DD coil are analyzed and compared under three shielding conditions: no shielding,single core shielding and double shielding of magnetic core and aluminum plate,and the transmitting and receiving coils of magnetic coupler in wireless charging system are designed.The core structure of the magnetic coupler is optimized on the basis of the common core structure to increase the coupling coefficient and minimize the amount of ferrite core.In view of the shortcomings of the common double-layer shielding structure,a new double-layer shielding structure and a new three-layer shielding structure are proposed,which can reduce the weight and cost of the shielding layer in compliance with flux leakage standards,and the optimization design flow of the magnetic coupler shielding structure is given.On the basis of the above finite element simulation,the physical magnetic coupler was made and the experimental platform of the wireless charging system was built to verify the feasibility and correctness of the proposed new double-layer shield structure and the new threelayer shield structure.The experimental results show that the new double-layer shielding structure can make the lateral flux leakage of the magnetic coupler less than 27μT at the rated output,which proves the correctness and effectiveness of the structure;the new three-layer shielding structure achieves the same shielding effect at side and top as the full-cover doublelayer shielding structure,reduces the magnetic core consumption by 71.2% and aluminum consumption by 80%,and increases the coupling coefficient by 2.24%,which proves the superiority of the new three-layer shielding structure. |
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