Safety Assessment Of Electromagnetic Exposure Of Wireless Charging Coils Of Electric Vehicle To Minors

Recently,while vigorously developing economic construction,China has also learned the lessons of "development first and governance" from developed countries,and environmental governance and economic development have been combined.As an excellent energy-saving and emission-reducing product,electric vehicles have received extensive attention and applications.Due to the many advantages of wireless charging technology,it is used to charge electric vehicles.But the power of wireless charging of electric vehicles is relatively large,which may pose a threat to human health.Therefore,it is necessary to conduct a safety assessment of human electromagnetic exposure.In an increasingly developed modern society,it is very common for children to ride in cars,however,because their body tissues are not fully mature,the dielectric parameters are difficult to measure,and there are fewer studies on safety assessment of children electromagnetic exposure.Therefore,this thesis pays attention to the electromagnetic exposure level of the electromagnetic field of the electric vehicle wireless charging coil in the body of the child passenger.In order to evaluate the electromagnetic safety of children in the electromagnetic environment generated by the wireless charging coil of electric vehicles,firstly,threedimensional drawing software Solid Works was used to establish a three-dimensional child passenger(7-10 years old)sitting posture model with an actual height of 1.43 m.At the same time,in order to compare and study the electromagnetic exposure level between the child passengers and the adult passengers under the same electromagnetic exposure conditions,the actual height of 1.75 m adult passenger sitting model was established,too.The human head model adopted the international standard three-layer ball head model,and the 4-order ColeCole model was used to calculate the electrical conductivity and relative permittivity of the main tissues of child passengers and adult passengers,and assigned values to human body materials.Secondly,the electric vehicle and the wireless charging coil model were established.According to the circuit theory,the simplified circuit of the electric vehicle wireless charging is analyzed and modeled,and the coil model and the circuit are established for field-circuit coupling.Then assemble the electric vehicle wireless charging system model in the software COMSOL Multiphysics which based on the finite element method.Then respectively placed the passenger model on the four passenger positions of the car for simulation calculation.Finally,the electromagnetic exposure levels of child passengers and adult passengers were compared,and the two are compared with the electromagnetic exposure safety guidelines ICNIRP limits set by the International Commission for Non-Ionizing Radiation Protection,and a conclusion carried out.The results show that passengers in the vehicle will receive a certain dose of electromagnetic radiation when an electric vehicle is wirelessly charged.The maximum value of the induced electric field intensity of the child passenger’s brain tissue is 1.83V/m,which is2.10% of the ICNIRP limit;the maximum value of the magnetic induction intensity of the child passenger’s brain tissue is 2.90 μT,which is 46.4% of the ICNIRP limit.The maximum value of the induced electric field intensity of the adult passenger brain tissue is 1.01V/m,which is 1.16%of the ICNIRP limit;the maximum value of the magnetic induction intensity of the adult passenger brain tissue is 2.14 μT,which is 34.24% of the ICNIRP limit.The electromagnetic exposure values of the head and brain tissue of child passengers and adult passengers are lower than the ICNIRP limit,but the magnetic induction intensity and induced electric field intensity of the head and brain tissue of child passengers are greater than those of adult passengers.It means that because the size and dielectric parameters of the child passengers’ body tissues are different from those of adult passengers,the induced electric field intensity and magnetic induction intensity of their brain tissues in the same riding position are both larger than that of adults when the they are exposed to the electromagnetic environment generated by the wireless charging coil.It is recommended that child passengers leave the car when the electric car is wirelessly charged.