Research On Metal Influence Characteristics And Coexistence Interference In Wireless Charging System Of Electric Vehicle

As an important measure to alleviate energy supply and promote sustainable economic development,electric vehicles have gradually become one of the crucial strategic industries in china.Due to its advantages in charging safety,reliability and convenience,wireless power transmission technology has been widely used in the development of Electric Vehicle Wireless Power Transmission(EV-WPT)technology.However,with the deepening of the research,on the one hand,EV-WPT system will inevitably be affected by the surrounding metal objects,causing the temperature of the metal objects to rise,which may cause fires or damage the equipment,and at the same time,it may also interfere with the magnetic field distribution between the transmission coils and affect the transmission performance of the EV-WPT system.On the other hand,magnetic flux leakage will be generated to radiate electromagnetic fields to the surrounding environment,which may interfere with the normal operation of the surrounding equipment.Therefore,it is of great significance to study the metal influence characteristics of the EV-WPT system and the coexistence interference between EV-WPT system and surrounding communication equipment.Focusing on the above two problems,this dissertation carried out the following research on the metal influence problem and coexistence interference problem of EV-WPT system and obtain relevant conclusions:First of all,the theoretical and simulation model of EV-WPT system with metal material is established.Based on the material characteristics,the influence of ferromagnetic metal and non-ferromagnetic metal on EV-WPT system is analyzed respectively,and verified by simulation.Focusing on the simulation and modeling analysis of the typical application scenarios of the three-dimensional garage and reinforced concrete pavement of the EV-WPT system,the influence characteristics of the complex metal environment on the EV-WPT system are obtained,and four targeted performance optimization measures are proposed.The optimization measures can effectively solve the problems of resonance point deviation and serious electromagnetic leakage of WPT system in the metal background environment,thereby improving the working performance of the EV-WPT system.Furthermore,according to the difference in metal influence characteristics,an overall scheme for metal foreign object detection in the EV-WPT system based on frequency scanning is proposed.This scheme can not only determine the location of the metal foreign object,but also distinguish the type of the metal foreign objects,including cans,heat sinks,etc.,which can effectively reduce potential safety risks when metal foreign objects fall in the middle of the energy transfer coil.Furthermore,the impact characteristics of key parameters on the performance of the detection system are analyzed,which provides theoretical guidance for the optimal design of the detection system.Secondly,the operating frequency of EV-WPT system 81.38 k Hz～90k Hz(the center frequency is 85 k Hz)is vertified based on the comprehensive consideration of the spectrum resource occupancy and the key indicators of the EV-WPT system,and the coexistence interference scenario is determined by means of spectrum overlap.The interference characteristics of EV-WPT system and the interference characteristics of the AM broadcasting system are respectively analyzed.Considering the working characteristics of these characteristics synthetically,a scheme for evaluating the coexistence of the EV-WPT system and the AM broadcasting system based on harmonic analysis is studied.The scheme fills the vacancy in the research of frequency coexistence interference in the field of electric vehicles and wireless communication,and contributes to the promotion and application of the EV-WPT system.At the same time,the impact characteristics of the key parameters of EV-WPT system on the system coexistence are analyzed,and the conclusion that using a reasonable size circular coil and LCC topology can reduce the interference of EV-WPT system to potentially disturbed devices is drawn,which provides technical guidance for improving the coexistence tolerance of the EV-WPT system.Furthermore,the coexistence interference electromagnetic co-simulation model adopting the combination of field and circuit is established and the coexistence passability analysis is carried out.The analysis results are as follows: For the model built in this dissertation,when considering wall attenuation,the two can coexist when the AM broadcast is 5m away from the center of the coil.Finally,the EV-WPT system metal foreign object detection experimental platform and the EV-WPT system and AM broadcasting system coexistence experimental platform are built.Relying on this experimental platform,the experimental results prove the feasibility of the metal foreign object detection scheme proposed in this dissertation,and also verify the consistency of the simulation results of the coexistence passability of this dissertationwith the experimental results.