| Magnetically-coupled resonant wireless power transfer(MCR-WPT)technology has high transmission efficiency,long transmission distance,safety and flexibility.It has broad application prospects in mobile phones,smart home and some special occasions.This thesis takes the wireless charging of MCR-WPT as the application scenario,focuses on optimizing the core structure,designs and making a prototype of the magnetic coupling mechanism of MCR-WPT.The experimental results show that,after optimization,the system's anti-offset capability is increased by 98%and the transmission distance is increased by 81%in terms of output power;the anti-offset capability of the system is increased by 106%in terms of transmission efficiency,and the transmission distance is increased by 89%;the magnetic shielding capability of the system is increased by 42%.Firstly,this thesis introduces the components of the MCR-WPT system and the energy transmission process,establishes the mutual inductance equivalent circuit model and the equivalent magnetic circuit model of the magnetic coupling mechanism.The coupling coefficient,high frequency resistance of coil,frequency and load are studied for the influence of system performance.The skin effect and frequency bifurcation are analyzed.What mentioned above lays the foundation for the design of the magnetic coupling mechanism.Secondly,aiming at the problem of low coupling coefficient,low output power and low transmission efficiency of MCR-WPT,this thesis compares the common coil structures and selects a planar circular coil structure.In combination with the requirements of the transmission distance and output power of the subject,the coil parameters are determined.The appropriate magnetic material is selected and the typical magnetic core structure is compared for the further optimizing of planar core structure.Under the condition of the high transmission performance of the system,different planar magnetic core structures are designed with the principle of reducing the amount of material used for the core material.After the simulation analysis,the planar meter-shaped magnetic core structure is obtained and coupling coefficient of the system is significantly promoted,its material are only a quarter of the planar square-shaped magnetic core structure.Finally,a system experiment platform is set up to test the offset characteristics,transmission distance characteristics,and electromagnetic shielding characteristics of three types of systems:air-coil,planar square-shaped magnetic core and planar meter-shaped magnetic core.The experiments verify the conclusion that the flat meter-shaped magnetic core structure makes the amount of magnetic core significantlyreduce in the case of higher transmission performance of the system.At the same time,the performance of the system in anti-offset,transmission distance and magnetic field shielding is significantly improved. |
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