| Wireless power transmission solves these problems such as line aging and sparks generation in traditional wired power supply,and it has great application potential.Magnetically coupled resonant wireless power transmission utilizes a high-frequency resonant magnetic field to achieve wireless power transmission,which is one of the current research hotspots in the field of wireless power transmission.In principle,this technology can achieve high-efficiency power transmission in the middle distance,but it cannot meet the practical requirements in terms of transmission distance,efficiency,and power.There are still some problems that need to be solved urgently.This paper focuses on the magnetic coupling mechanism of the magnetically coupled resonant wireless power transmission system,and aims to improve the practicability and safety of the system..The main contents of this paper include the following aspects:Firstly,this paper introduces the development background and significance of wireless power transmission,describes several ways to achieve wireless power transmission,and briefly describes their transmission principles and features.Then,the research status and existing problems of the magnetic coupling mechanism are mainly discussed,and the research direction of the magnetic coupling mechanism and the electromagnetic safety issues that cannot be ignored are explained.Based on the circuit theory,a series-series compensation topological equivalent circuit model with two coils structure is established.The mathematical expressions of the maximum receiving power of the load and the maximum transmission efficiency are derived,and it is determined that the maximum transmission efficiency is only related to the transmission quality factor,which provides the target for the design of the magnetic coupling mechanism.Then,the electrical parameters and magnetic field distribution of 17 kinds of coil structures are compared and analyzed by finite element simulation,and the square double-layer dislocation 45° coil structure with maximum transmission quality factor is designed.In addition,the changes of coil electrical parameters are analyzed when the coil wire diameter,turn pitch,number of turns,layer pitch and radius change.And the geometric parameters of the coil are determined.At the same time,the expression of coil coupling coefficient is deduced according to the relevant magnetic circuit model and the divided self-coupling and mutual-coupling regions.And the principle of magnetic coreaddition is obtained according to the expression.On the premise of equal amount of magnetic cores,the layout of radial type 36 magnetic cores is determined,and continues to optimize.In the end,0.58 times the amount of the flat core is used to obtain a better coil coupling effect than the flat core.Finally,the shielding principle and shielding effectiveness of the passive shielding method are introduced theoretically.The equivalent circuit of the wireless power transmission system with metal plates is established.The theoretical formula of the influence of metal plates on the system is given and verified by simulation.In addition,a new three-layer shielding structure which combines magnetic conductive material with conductive material is proposed by using the parameter scanning function.Under the national electromagnetic radiation safety standard,the electromagnetic safety range of the magnetic coupling mechanism is doubled in the horizontal direction and 9.4 times in the vertical direction;the safety of system work is greatly improved.At the same time,the designed magnetic coupling mechanism is made,and a simple experimental platform is built on this basis.The transmission efficiency of the magnetic coupling mechanism is78.57% and that of the whole system is 58.14% at the transmission distance of 150 mm. |
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