Research On Magnetic Couplers And Their Electromagnetic Edge Effects For Wireless Charging Systems

Since limitations of transmission lines can be eliminated in Wireless Power Transfer(WPT)system,it has better flexibility and safety,and its future applications are fantastic.At present,the low efficiency of the WPT system restricts its wide application.A magnetic coupler is the core component of WPT system.The transmission efficiency of magnetic coupler restricts the further improvement of WPT system efficiency.Since the coil structure,magnetic shield structure and edge effect in the magnetic coupler have important influences on the transmission efficiency of the magnetic coupler,a new magnetic shield structure based on the magnetic coupler is proposed in this study to suppress the edge effect and improve the transmission efficiency of the magnetic coupler.The specific work of this paper is as follows:Firstly,the magnetic coupler in inductively coupled power transform system of electrical fork truck is modeled and its structure is optimized.The structure and material of the composite magnetic shielding layer in the magnetic coupler are analyzed,and the equivalent magnetic circuit model and equivalent circuit model of the magnetic coupler are established respectively.By analyzing and simplifying the equivalent circuit model,the relationship between the geometrical dimensions of each layer in the composite magnetic shield layer on the receiving side of the magnetic coupler and the transmission efficiency of the magnetic coupler is obtained.On this basis,the objective function was established by combining the transmission efficiency of magnetic coupler and the cost of manufacturing the composite magnetic shielding layer,respectively.The Pareto optimal solution of the geometric size of the composite magnetic shielding layer was obtained by using the genetic algorithm of non-dominated sorting with elite strategy,so that the Pareto optimal solution could both maximize the transmission efficiency of magnetic coupler and minimize the production cost.Secondly,the composite magnetic shielding layer and edge effect ring layer of magnetic coupler are simulated.Combined with JMAG finite element simulation software,the geometric dimensions of the composite magnetic shielding layer were simulated to verify the correctness of the results obtained by the algorithm.On this basis,the causes of edge effect of magnetic shielding layer are analyzed,and a ring structure of edge effect is proposed to suppress the edge effect.Through JMAG finite element simulation,the geometric size of the edge effect annular layer was selected and the migration ability was verified.Finally,the magnetic coupler and edge effect ring layer were made,and the experimental platform was built for experiments.Simulation and experiment results show that the proposed structure is correct and effective,the edge effect can be suppressed,and the transmission efficiency of the magnetic coupler is improved.Therefore,the research has certain practical significance.