Research And Design Of Shielded Wireless Power Transfer System

With the deep research and application of Wireless Power Transfer(WPT)technology,the electromagnetic compatibility problem has been more and more attention.Because the energy transfer of WPT is using the alternating electromagnetic field,the transmitting and receiving coils are generated large electromagnetic interference,which will have a greater impact on the user and other peripheral equipment.Considering the above factors,the research on electromagnetic compatibility of WPT has become increasingly urgent and necessary.At present,the research mainly focuses on the design of shielding and the study of magnetic field distribution,but seldom discusses the influence of shielding material on system parameters,shielding performance and transmission performance.In view of the above shortcomings,this paper has used the theoretical analysis,finite element simulation and experimental verification method to research this problem.?The shielding effectiveness of the planar shield is analyzed by the Transmission Line Theory.Through this theory,the shielding effectiveness of three kinds of shielding materials,such as MnZn ferrite,Fe-Si-Al powder core and aluminum plate are calculated and analyzed.The results show that the shielding effectiveness of aluminum plate is the best,followed by Mn Zn ferrite,while Fe-Si-Al powder core is poor.?Based on the principle of electromagnetic field,the field of shielded WPT system is analysed,and the simulation model of the shielded WPT system is built in COMSOL.In the finite element simulation,MnZn ferrite was used as the object to study.The influence on the transmission and shielding performance of the WPT system before and after shielding is studied by respectively changing the transmission distance,input voltage,load and operating frequency.?Since the self-inductance of the transmission coil will change after shielding,the system will be in a non-resonant state if directly putting shielding into the WPT system,which will extremely affect the transmission performance.Ensuring the transmission system is working in the resonant state,the system is modeled by circuit principle,and the change of the transmission coil before and after shielding is deduced.On the basis of the above,the influence of the three kinds of shielding materials on the transmission performance.The analysis shows that MnZn ferrite and Fe-Si-Al powder core could improve effectively System transmission performance,while aluminum plate will weaken the system transmission performance.In these three kinds of shielding materials,MnZn ferrite can not only enhance the transmission performance of the WPT system,but also enhance its electromagnetic compatibility.?Based on the above analysis,the experimental platform of the shielded WPT system is established.The influence of the magnetic material shield on the coil parameters,transmission efficiency and shielding effectiveness of the WPT system is analyzed by finite element simulation and experiment.It is verified that the permeability magnetic material can enhance the transmission performance and shielding performance of WPT system,and can effectively improve the overall performance and safety of the system.