Study On Power Fluctuation Of Segmented Rail Dynamic Wireless Charging System

Wireless power transmission technology is an effective non-contact power transmission technology.In the past decades,it has been widely studied and developed rapidly.Its safety,environmental protection,convenience and other advantages make it a successful technological revolution in portable consumer electronics,biomedical,and electric vehicles and other applications.The application of dynamic wireless power transmission technology in the field of electric vehicles can effectively solve the problems of high charging frequency and long charging time of electric vehicles.But the disadvantage of dynamic wireless charging technology is that it is difficult to have both high system efficiency and low output power fluctuation.This paper analyzes the fluctuation of system output power caused by mutual inductance fluctuation in the process of dynamic wireless charging.The bipolar primary side transmitting coils and combined secondary side receiving coils combined with dual-output circuit structure are adopted to reduce the mutual inductance fluctuation at the junction of segmented rail-type in the process of dynamic wireless charging.A new topology of constant current and constant voltage switching is proposed to realize the free switching between constant voltage mode and constant current mode.Firstly,this paper analyzes the common compensation topologies of wireless charging system,and focuses on the dual-output circuit structure of LCCL-LCCL and LCCL-S topologies.It is concluded that the constant sum of mutual inductance between double receiving coils and primary coils can realize the constant system output power.The mathematical model of magnetic coupling mechanism is established to provide theoretical basis for further optimization of magnetic coupling mechanism.Next,the transmission characteristics of the wireless charging system under constant voltage and constant current modes is analyzed,and the influence of compensation inductance on the output characteristics of LCCL topology under resonant state is analyzed.A new topology switching mode of constant voltage and constant current is proposed.Then,based on the flux theory,the feasibility of realizing the constant mutual inductance value with the combination of primary side bipolar coil and secondary side combined coil is analyzed.From the perspective of wires economy,the maximum mutual inductance per unit line consumption is taken as the optimization objective to optimize the length width ratio of secondary coils.The reasons for mutual inductance fluctuation in dynamic wireless charging system are explored,and the magnetic coupling mechanism is further optimized from the perspective of reducing mutual inductance fluctuation rate.Finally,the magnetic coupling mechanism and the system circuit are simulated and an experimental platform is built.The accuracy of the mathematical model and the correctness of the proposed theory are verified by comparing the theoretical analysis results,the finite element simulation results and the experimental results.