Research On Key Technologies Of Emission Sources For Wireless Dynamic Power Transmission System For Electric Vehicles

In recent years,as the world’s energy shortage and pollution problems have become more serious,the development of electric vehicles to replace fuel vehicles has become a common goal of all countries.Due to the limitations of low power density,high cost,weight,etc.,the development and application of battery-powered devices is facing unprecedented technical challenges.As a novel power-on mode,Wireless Power Transfer(WPT)provides a new way for energy harvesting in electric vehicles,reducing the reliance on batteries.This paper takes the transmitting power in the wireless charging system as the research object,and mainly studies the following aspects:Firstly,the overall structure of the wireless charging system is briefly introduced,and three important parts of the transmitting power supply,the coupling mechanism and the secondary conversion circuit are analyzed.The basic topology of the cascaded inverter circuit is designed to meet the performance of the system.Claim.The mathematical model of the pre-buck circuit is established by the state space averaging model and the small-signal system model.The inverter circuit of the transmitting power source is analyzed,and the relationship between the bus voltage and the bus current is obtained.Secondly,through the modeling and analysis of the transmitting power,the current mode is used to control the output current of the transmitting power source in the case of a sudden change in load impedance in the dynamic wireless charging system.Designing a suitable PI controller enhances the stability of the system and provides a stable current for the transmitting coil,thereby ensuring stable reception voltage at the secondary receiving end.By using the method of sampling the effective value of the output current,the system can quickly and accurately detect the output current.The simulation analysis was carried out by MATLAB software to verify the above theoretical analysis.Afterwards,for the dynamic wireless charging system due to environmental and magnetic core factors,the natural resonant frequency of the system changes,using the frequency tracking technology to achieve the system operating frequency to follow the natural resonant frequency in real time.The natural resonant frequency of the system is roughly determined by the frequency sweeping technique to activate the transmitting power source,and then corrected by the frequency tracking technique to be equal to the resonant frequency.The traditional phase-locked loop and the all-digital phase-locked loop are analyzed,and an improved scheme is designed based on it to meet the requirements of the dynamic frequency of the dynamic wireless charging system following the natural resonant frequency.And through the MATLAB software for simulation verification.Finally,the Infineon XMC4500 is used as the main control chip to build a launch power experimental platform.Hardware systems and software systems are designed according to dynamic wireless charging system requirements.The dynamic wireless charging system is tested as a whole,which verifies that the designed transmitting power can meet the design requirements of the dynamic wireless charging system,has excellent dynamic performance and reliability,and has good application prospects.