| Because of its excellent flexibility,security,reliability and convenience,wireless power transfer has become a research hotspot at home and abroad.A magnetic coupler is the key component of wireless power transfer system.However,at present,the magnetic coupler based on ferrite shielding or ferrite plus aluminum shielding has problems of large volume,heavy weight and high cost,which seriously restrict the further development and application of wireless power transfer technology.Therefore,this paper focuses on the coil characteristics of the magnetic coupler and the optimal design of the shielding layer,and proposes a new type of core structure and a new type of hybrid shielding structure.The specific work is as follows:Firstly,the theoretical basis of optimal design of magnetic coupler is analyzed.The circuit and magnetic circuit model of the magnetic coupler are established,and the influence of the electrical parameters of the magnetic coupler on the output power and efficiency of the system is analyzed.The necessity of electromagnetic shielding is discussed.The principle of electromagnetic shielding and its effect on the electrical parameters and magnetic field distribution of magnetic coupler are analyzed.Secondly,the characteristics of magnetic coupler coil are studied.The coil structures commonly used in wireless power transfer system are summarized,and the electrical parameter characteristics,magnetic field distribution characteristics and offset characteristics of circular coil and Double D(DD)coil in free space,as well as the effects of ferrite shielding layer and ferrite plus aluminum shielding layer on the coil characteristics are deeply studied.The design process of magnetic coupler coil is given,and the receiving coil of magnetic coupler for wireless power supply fruit and vegetable machine is designed as an example.Thirdly,in order to improve the coupling performance of the system and reduce the amount of ferrite,the influence of core shapes on the electrical parameter characteristics,magnetic field distribution characteristics and offset characteristics of the magnetic coupler is studied.A new type of magnetic core structure is proposed and its structural parameters are optimized.In order to effectively reduce the magnetic flux leakage and improve the coupling performance of the system,the influence of the structure of ferrite and aluminum shield on the characteristics of the magnetic coupler is analyzed,and a new hybrid shield structure is proposed and its structural parameters are optimized.Finally,according to the parameters of finite element simulation design,the magnetic coupler is made and verified by experiments.The experimental results show that the coupling coefficient of the concave core is improved by 6% more than that of the disk core,and the amount of ferrite is reduced by 34%.The improvement effect of the new hybrid shield on the coupling coefficient of the system is 11.36% higher than that of the disc shield,and the magnetic flux leakage at the specified location is less than 27?T at the rated output.The correctness and feasibility of the new core structure and the new hybrid shielding structure are verified. |
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