| Wireless power transmission technology refers to a kind of technology that utilizes the distribution or propagation characteristics of electromagnetic field and electromagnetic wave in physical space and adopts non-conductor direct contact mode to realize the transmission of electric energy from power supply side to load side.The technology solves the problem of power supply in the occasion of unfit towing conductor and greatly increases the convenience of power supply mode.With the in-depth study of the principle of wireless power transmission and the continuous improvement of technology,its application field has been expanded year by year.Electromagnetic induction or magnetic resonance wireless power transmission technology can provide electric energy to electric vehicles at rest or in motion to improve the flexibility of charging process to a certain extent,and may become an important way of charging electric vehicles in the future.Because of the existence of electromagnetic field in the working process of the technology,it is very important to install electromagnetic shielding device on the coupling mechanism and control the electromagnetic field around the coupling mechanism in a safe range.In this thesis,the influence of electromagnetic shielding structure on the structure parameters,performance and space electromagnetic field of electric vehicle wireless charging system is studied.A new electromagnetic shielding structure is proposed,and the three-dimensional space electromagnetic field is built.The electromagnetic field distribution around the coupling mechanism is measured.Firstly,this thesis expounds the working principle of the resonant electric vehicle wireless charging system,analyzes the basic structure of the whole system,introduces the principle of magnetic material shielding and non-magnetic material shielding,establishes the mathematical analytical model,and derives the expression of space electromagnetic field.Secondly,the simulation model is built by finite element simulation software,and the variation of self-inductance mutual inductance with frequency and the distribution of electromagnetic field in free space are analyzed.Then the different effects of the two structures on the system structure parameters,performance and electromagnetic field distribution are analyzed.Then a new shielding structure is proposed by combining the two shielding structures,which not only ensures the efficient operation of the system,but also meets the international standards of electromagnetic safety.Then,in view of the lack of full-automatic electromagnetic field measurement system,this paper builds a 3D electromagnetic field measurement system,which can display the spatial electric field and magnetic field in three-dimensional form,which is of great significance to the electromagnetic field analysis.Finally,in order to verify the effectiveness of the new shielding structure,this paper builds a electric vehicle wireless charging system experimental platform,electromagnetic shielding experiments are carried out to verify the effectiveness of the new structure,to ensure the safety of the wireless charging system. |
