Research On Electromagnetic Radiation Of Electric Vehicle Wireless Charging Coil And Its Impact On Human Safety

Electric vehicle(EV)has been supported by national policies in recent years because of its advantages of environmental protection,energy saving and no exhaust pollution.The technology of magnetic coupled resonance wireless power transmission(WPT)is not bound by cable,and it has high transmission power,high efficiency and moderate transmission distance.It has become a new and effective charging mode of electric vehicles.When the magnetic coupling mechanism works,the electric energy is transformed into high frequency electromagnetic field(EMF),which inevitably leaks into the non-working area around the coupling mechanism,which will pose potential threat to human safety.Based on the modeling of coupling mechanism,the electromagnetic field distribution characteristics of WPT system and the bioelectromagnetic safety in vehicle environment are studied.The electromagnetic shielding scheme is proposed in view of the electromagnetic field exceeding the standard.In addition,the EMF test system for EV wireless charging human body exposure is designed and manufactured,and the electromagnetic field is measured by building the wireless charging platform.The main contents are as follows:Firstly,the principle of the magnetic coupled resonant wireless charging technology is studied.The different models of coupling coils and four typical resonant compensation structures are analyzed.The hybrid compensation topology of lcc-s/lcc with constant current and constant voltage charging is studied.The paper summarizes the structure models of different coils and compensation networks by using two-port network model,analyzes the input power,output power and efficiency,and theoretically deduces the spatial electromagnetic field distribution of rectangular and circular current carrying coils.Secondly,the model of the square coil with rectangular section of EV WPT is established.The transmission characteristics of coupling mechanism are analyzed by field circuit co-simulation.Meanwhile,the magnetic field distribution cloud and energy density cloud graph in the aligned state are obtained to analyze the electromagnetic field distribution characteristics in the ideal working state of WPT.In addition,aiming at the non-ideal working state of the coupling mechanism,the electromagnetic field distribution characteristics under the conditions of radial offset,air gap change and deflection are simulated.Thirdly,the coupling mechanism model of WPT plane circular spiral coil is used to simulate SAR exposed to WPT electromagnetic field in the head,heart and foot under the condition of non-vehicle.In addition,the car shell model is established,and the human body voxel Hugo model is added.The field circuit co-simulation method is used to simulate the human body in different positions with standing,lying and sitting posture in the vehicle environment,and the SAR,power density,current density and magnetic flux density of human organs exposed to WPT system electromagnetic radiation were obtained.The comprehensive harm index of electromagnetic radiation?_hurt is established to evaluate the bioelectromagnetic safety of WPT.Aiming at the problem of EMF exceeding the standard,the electromagnetic shielding scheme is designed for EV wireless charging system.Finally,we design and develop a transmitter and receiver panel without radiation platform and EMF three-dimensional test system of EV wireless charging.EV WPT experimental platform was built by purchasing EV wireless charging pile samples,using no radiation platform and programmable load.The electromagnetic field around the wireless charging pile was measured in 10 meter Radio Anechoic Chamber of Nanrui group.The measured results are compared with the simulation results,ICNIRP guidelines and GB/T38775.4-2020 to provide practical data support for the evaluation of human electromagnetic safety of EV WPT system and the optimization of electromagnetic shielding of wireless charging pile.