| In recent years,wireless charging technology has been widely applied in electric vehicles,medical and communication industries with its own advantages.Inspection robot is one of the daily inspection equipment of substation,and its charging method is also realized by wireless charging.However,with the high electromagnetic field in the substation,the electromagnetic compatibility between the wireless charging system and the external electromagnetic environment has gradually emerged.In addition,the wireless charging technology of inspection robot is based on the principle of magnetic resonance to realize energy transmission,which requires an appropriate shielding structure to limit the high frequency magnetic field generated by the system.The traditional aluminum plate shielding structure seriously affects the electrical parameters of the wireless charging system,and leads to the decrease of transmission efficiency.Therefore,ferrite materials with high permeability are usually combined with metal structures to reduce the influence of traditional metal shielding materials on wireless charging system.Based on this,this paper studies the characteristics of the wireless charging system of the inspection robot and the electromagnetic radiation characteristics of the wireless charging robot in the complex electromagnetic environment of 500 k V substation.Combined with theoretical analysis and simulation calculation,a ’ box ’ aluminum plate-ferrite composite shielding scheme is proposed and its effectiveness is verified by laboratory simulation experiments.The specific work is as follows :(1)Based on the principle of magnetic coupling resonant wireless charging,the field-circuit coupling model of wireless charging system of inspection robot is built.The influence of complex electromagnetic environment of 500 k V substation on transmission power of wireless charging system of inspection robot is analyzed.The calculation results show that the influence of substation power frequency magnetic field on wireless charging system can be ignored.The 100 k Hz magnetic field has a serious impact on the system,resulting in a decrease in transmission efficiency,and different magnetic field directions have different impacts on the system.The influence of electric field on system security is ignored.(2)The influence of metal shielding structure on electromagnetic characteristics and electrical parameters of wireless charging system is analyzed,and the metal shielding model is built.The influence on magnetic shielding and electrical parameters of wireless charging system is studied.The influence of aluminum plate thickness,position and geometric structure on the magnetic shielding characteristics of metal shielding structure and the electrical parameters of the system are calculated and analyzed.The plate metal structure is optimized to a box structure.The simulation results show that the metal structure can effectively limit the leakage magnetic field within the specified safety limit.However,due to the eddy current in the metal plate,and the near magnetic field intensity is proportional to the eddy current,the metal structure will lead to a significant increase in the transmitter voltage and current,and a significant decrease in transmission efficiency.(3)The influence of aluminum plate-ferrite composite shielding structure on magnetic shielding characteristics and electrical parameters of wireless charging system is calculated and analyzed.The results show that the voltage and current of the emitter return to normal level after adding ferrite,and the current density in the metal plate decreases by 57.9 %.Then,the ferrite structure was optimized to reduce the usage of ferrite by 60 %.Finally,when the composite shielding structure is used,the transmission efficiency of the wireless charging system is increased from 75.2 % and 58.4 % to 93.54 % when the wireless charging system is in a 100 k Hz magnetic field environment in different directions.(4)The magnetic shielding simulation experiment of wireless charging system of inspection robot is carried out to study the influence of different metal shielding structures and ferrites on the magnetic shielding characteristics and electrical parameters of wireless charging system.The experimental results show that the aluminum plate will seriously affect the electrical parameters of wireless charging system.Especially the bottom shielding plate has great influence.Increasing ferrite structure can effectively alleviate the influence of aluminum plate.The effectiveness of ferrite structure to alleviate the influence of metal shielding structure on the electrical parameters of wireless charging system is verified. |
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