Research On Electrical-field Coupled Power Transmission System With Dual Transmitting Terminals Based On Full-capacitive Coupling Model

Wireless power transfer delivers electric energy by space invisible medium,it's a new way to supply power by getting rid of cable bondage that can overcome the difficulties of plugging and firing,wear and leakage of electrical equipment.With the development of science and technology and the improvement of people's living standards,people pay more and more attention to environmental protection,green,portable,safety,etc,making it possible for wireless power transfer technology applied to electric energy.The capacitive power transfer(CPT)system uses high-frequency alternating electric fields to transfer energy,and the coupling mechanisms are make up of aluminum or copper plates.The CPT system has the advantage of good flexibility,low cost and lightweight,and it will not cause eddy current loss with the existence of surrounding metal objects.It has unique advantages for the high-power application of rail transit,electric vehicle charging and so on,which attracts domestic and foreign scholars to research on it.This paper focuses on the research of CPT coupling mechanisms and power raising.First,the full-capacitive coupling structure of four-plate and six-plate is decoupling equivalent to two-port and three-port circuit model.Then,based on the analysis of two typical CPT high-power output topologies,a multi-stage LC topology has proposed,which can realize port voltage superposition and high-power output.The fundamental harmonics approximation method is used to analyzing the resonant network,and using the same controller DSP to control the driving circuit to maximize the output power of the CPT system.The traditional CPT system utilizes single-phase H-bridge inverter and single transmitter to transfer power.Because of the CPT system is limited by the capacity constraints of the inverter,so that it may not be able to meet the high power requirement of rail transit applications.To realize the system's high power output,dual transmitting and single receiving terminal CPT system is proposed in this paper by paralleling two inverters so that the total capacity of input power is enhanced.The six-plate capacitive coupler model is simplified as three-port circuit,and finite element analysis(FEA)by Maxwell is used to simulate the coupling capacitors.Considering the effect of mutual coupling between two transmitting mechanisms,this paper presents the resonant circuit parameter configuration method.At last,the system's working principle is analyzed in detail,and an experiment is designed at the working frequency of 500 kHz.The DC-DC efficiency is up to 90.6% when the output power is 1.47-kW.The current flowing through the switching device in the dual transmitters is half of that in the single transmitter with the same power output in the CPT system.The experimental results show that the proposed methods are effective and feasible.