Study On The Coupling Mechanism Magnetic Radiation Suppression Method For Wireless Power Transfer System Of Electric Vehicle

With the emerging problems such as climate change,energy crisis and environment pollution,electric vehicles(EVs)gain more and more attention globally.While,traditional conduction way of EV charging is connected by cables,which brings obvious disadvantages,such as tedious charging process,environmental limitations and relatively weak battery mileage.With the development of wireless power transfer(WPT)technology,it has been broadly applied to the field of EVs.Combined with the characters of WPT technology,it can be utilized to transfer power from the grid to EVs,through which process the defects existing in traditional wired contact conduction can be eliminated.WPT systems for EV can be classified into two types,dynamic mode supplying and static mode charging,respectively.In the static mode,EV should stay in a fixed point to charge.In the dynamic mode,there needs to pave coil rails to active charge for EVs,the volume and weight of batteries can be reduced.Electromagnetic radiation of the two modes is different.This paper mainly studies the dynamic power supply mode.In this paper,the basic structure of electric vehicle WPT system is introduced.And an equivalent model is constructed for the magnetic circuit of coupling mechanism.To model the magnetic field distribution of the operation system,a finite element method is proposed.Simulation result shows that the receiving terminal of the coupling mechanism should be installed in the car chassis,where the magnetic induction intensity is relatively weak.Therefore,it meets the standard of safety requirements and guarantees lower radiation value around the area of passengers.Meanwhile,the magnetic induction intensity outside the vehicle is higher than the safety value standard,which needs some shielding measures.Therefore,based on the sectional track electric vehicle WPT systems,different passive shielding structures for electromagnetic radiation of coupling mechanism are studied.Through the work,it can conclude that the shielding band placed vertically for the coupling mechanism can obtain the best shielding results.Moreover,further work has been done on the vertical shielding band.Their different heights and materials have also been analyzed.Taking into account the actual engineering application of passive shielding,but also by the cost,construction and other factors.Therefore,this paper also studies the active magnetic shielding method.Basic principle of active magnetic radiation method is introduced.Then,the system model is built utilizing reverse shielding coil structure.Finite element method is introduced to calculate the position and coil parameters of the active shielding structure.Moreover,in order to analyze the system transmission power with active shielding structure,an leakage inductance equivalent model of electromagnetic coupling mechanism is proposed.The calculation results authenticate that the active shielding structure can effectively shield the magnetic radiation.Also,it has little influence on the transmission power of the system.Finally,to verify the theoretical analysis,an experimental setup is built to test the correctness of the active magnetic radiation shielding method.