| Wireless chaiging technology is one of the most active research directions in the field of electrical engineering,providing new ideas for power usage patterns.The magnetic resonant coupling wireless power transmission technology can increase the transmission distance and the transmission power at the resonant frequency,and has shown great application prospects in many fields.This thesis takes the inspection robot as the application scene and focuses on the research of shielding technology.The high-frequency electromagnetic field of the wireless charging system exists in the adjacent space around the robot.The distribution of the magnetic field has obvious directionality,and the intensity changes with the position.Therefore,it is necessary to find a new shielding method according to the distribution characteristics of the electromagnetic field of the system and evaluate the electromagnetic exposure value.Firstly,this thesis introduces the working principle of the wireless charging system.The expression of AC reflection impedance in the resonant state is derived by the theory of AC impedance.Using the equivalent circuit diagram of the mutual inductance model,the effect of quality factor and coupling coefficient on improving output power and efficiency is derived.By deriving the calculation formulas of skin effect,eddy current effect and magnetic saturation phenomenon,the special requirements for designing magnetic coupling mechanism at high frequency are obtained.Secondly,this thesis studies the working environment of the inspection robot,and analyzes the effects that the strong magnetic field generated by wireless charging may have on the surrounding environment.The ICNIRP-2010 guideline is selected as the evaluation basis after comparing different standards of electromagnetic safety.The magnetic coupling mechanism is designed according to the basic principle of the wireless charging system.The receiving coil and transmitting coil of the magnetic coupling mechanism are selected respectively according to the application scene of the inspection robot and the size requirements of the installation.The ANSYS 3D simulation model is built and the magnetic field distribution characteristics are investigated.The simulation designs of passive shielding and active shielding are carried out for the area beyond the magnetic field limit,and the optimal size and position of the shielding devices are determined.Finally,the magnetic field-testing platform of wireless charging system is built.The shielding effects of the ferrite plate,the receiving side horizontal aluminum plate,the receiving side vertical aluminum plate and the two active coils are experimentally studied.The results show that these methods can basically meet the limits of the guidelines.Among them,adding a horizontal aluminum plate and a suppression coil on the receiving side can achieve a better effect. |
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