Voltage Suppressing Method For Wireless Charging Of Electric Vehicles Based On Capacitive Power Transfer

At present,the electric vehicle industry mostly supplies power for the vehicle through the wired charging pile.However,there are still many problems in this way,such as easy wear,oversized space occupation,aesthetics problems,etc.With its development,the wireless power transfer is applied in the field of electric vehicle charging,which has absolute advantages over the traditional wired charging.There are many ways to realize wireless power transfer,all of which use the invisible medium to transmit energy from the transmitter to the receiver.Among them,the electric field coupled Capacitive Power Transfer(CPT)is a technology with apparent advantages because it is more economical,reliable,and safer than other methods.Therefore,it is more suitable to apply this technology in multi-metal products practically,such as electric vehicles.Because the electric field coupled wireless power transfer system uses a high-frequency electric field to transfer electrical power,there is a very high-frequency voltage on the electrical field coupling,which will induce a high voltage on the metals such as the surface of electric vehicles.At the same time,this will lead to serious safety problems.To solve the safety problems mentioned above,this paper mainly analyzes the application of electric field coupled wireless power transfer technology in electric vehicle charging.Firstly,the basic model of electric field wireless power transfer was established through theoretical analysis.According to the characteristics of the quadrupole coupling structure,the port characteristics of the vehicle shell-coupling structure-ground integrated structure were calculated.Then,the compensated topology of the system proposed was analyzed,and the parameters of the system components were determined according to the practical application.Furthermore,the calculation formulas of the voltage and current of each part of the system at work were calculated.Finally,the adjustable system parameters were selected,and the appropriate parameter selection range was calculated according to the international security standard.This paper presents a typology of electric field coupled wireless power charging system applied to electric vehicle charging.The optimal working conditions of suppressing the induced voltage on the vehicle shell when the system is working are selected through the systematic resonance optimization by CLL compensated topology,calculation and analysis.Finally,an electric field coupled radio energy transmission system with a shell voltage of only 3.88 V,an output power of 1.3kW,and overall efficiency of 87.7% is designed and implemented,which verifies the feasibility of the optimization strategy.