Research On Fast Response Method For Dynamic Wireless Charging Of Electric Vehicles

Dynamic wireless charging mainly based on the near-field strong coupling theory by the space electromagnetic field,which could transfer the energy at same resonant frequency when the receiving coil and transmitting coil diverged at relative position and realized the continuous electric energy transmission to electric automobile.When the load demand current changes,there is the problem of poor response characteristics in the electric vehicle dynamic wireless charging system,which leads to the huge impact of electric vehicle power equipment and load battery and reduced service life.Due to the maintaining the stability of the output current and effective system control method are the key factors to realize the rapid response of dynamic wireless charging.Therefore,This paper conducts research based on the compensation topology of wireless charging system,the coupling mode of two-sided coils and the method to improve the response characteristics of the system.(1)The mathematical model of dynamic wireless charging system is established by using the circuit theory,and four typical compensation topologies are compared and analyzed,and their shortcomings are obtained.According to the existing problems,the DLCC compensation topology is proposed in the dynamic wireless charging system,and the detailed theoretical derivation and simulation verification are carried out.(2)The dynamic coupling mode of wireless charging system is analyzed and studied,and the coil structure selection is completed.Secondly,considering the actual ground clearance of the electric vehicle chassis and the mutual inductance variation law of the bilateral coupling coil,the axial spacing is determined.Finally,the mathematical models of the two coupling modes are established and analyzed.The simulation results show that the coupling coefficient of the coupling mode selected in this paper fluctuates less in the moving process of the electric vehicle.(3)Aiming at the problem of slow regulation speed when the load demand current changes in the process of dynamic wireless charging of electric vehicles,a new solution is proposed.The large signal model of wireless charging system is established by using the extended function description(EDF)modeling method.On this basis,the small signal model describing the input disturbance state of wireless charging system is established The appropriate PI controller parameters are designed and applied to the actual system to achieve the purpose of rapid response of the system.(4)Combined with the detailed analysis of the wireless charging system in this paper,the specific parameters of resonance compensation of the system are designed on the basis of theory,and the experimental platform of dynamic wireless charging system for electric vehicle is built according to the simulation model.The above mathematical model and simulation model are verified by experiments,and the experimental results are in good agreement with the simulation results.