A Multi-output Coplanar Wireless Power Transfer Tree Network System With Load-independent Voltage

In recent decades,compared with traditional power transmission methods,wireless power transfer(WPT)technology has caused extensive research by scholars at home and abroad due to its features of safety,convenience,and efficiency.Among them,Magnetically-Coupled Resonant Wireless Power Transfer(MCR-WPT)technology has attracted much attention.Different from induction power transfer technology and radiation power transfer technology,MCR-WPT technology can achieve higher transfer efficiency in short and medium distances,higher misalignment tolerance,and is more suitable for people to use in daily life.With the popularization and miniaturization of electrical equipment,the limited size limits the capacity of the batteries that come with them,and people’s demand for charging is increasing day by day.At the same time,electrical equipment needs to have a stable charging voltage when supplying power.The multi-load and multi-relay wireless power transmission network structure can effectively supply power to multiple mobile devices at the same time,which has extremely high practical research value.Therefore,multiple loads,load independence and reduction of cross-coupling have become the three new directions of wireless power transmission system research.In this article,a multi-output coplanar wireless power transfer tree network system with load-independent voltage.The main research contents include the following points.(1)The main theoretical analysis methods of MCR-WPT technology are briefly described: coupled mode theory,filter theory and circuit theory.The important parameters in the system are introduced,and the relationship between them and the transmission efficiency of the system is explained through circuit theory.(2)The proposed MCR-WPT planar tree network structure is introduced.According to the circuit theory,the voltage-load isolation characteristic of the tree network is analyzed in detail from the perspective of the presence or absence of resistance loss.And using ADS simulation software and Mathematica calculation software to simulate and analyze the proposed network structure,again verify the voltage-load isolation characteristics of the network system,and ensure higher system efficiency.(3)Maxwell3D simulation software is used to simulate the coplanar four-coil system,study and analyze the magnetic field changes before and after adding the ferrite plate,and clarify the convergence effect of the ferrite plate on the magnetic field.The influence of the ferrite plate on the mutual inductance between the coils in the experiment is explained,and determines the approximate size of the ferrite plate.Analyze the magnetic field distribution on the coil and determine where to place the receiving coil.(4)The two main structure types of the MCR-WPT tree network system are constructed and verified experimentally.The proposed structure is successfully used to charge loads at different locations,the voltage-load isolation characteristics of multiple loads with different resistance values are verified.