| With the increasing demand for power in the world,power transmission modes are gradually diversified,and wireless transmission has emerged,includes inductive wireless power transmission,resonant wireless power transmission,microwave resonant wireless power transmission and so on.Among these,magnetically-coupled resonant wireless power transmission has been applied in many fields because of its good transmission performance.However,for some electronic devices used in the special environment such as in vivo and underwater,it is necessary to transmit electric energy as well as signals.In order to meet this demand,a new technology has emerged in recent years,called synchronous transmission of wireless information and power(Synchronous transmission of information and power).Based on this background,the technology of magnetically-coupled resonant wireless synchronous transmission of information,and power has been studied in his thesis and the electromagnetic radiation characteristics of the coupling coil in the system has been analysed.The main research contents and results are as follows:For wireless transmission system,the circuit characteristics of the magnetically coupled resonant wireless power transmission system are studied by equivalent circuit method,and the calculation methods of transmission power and transmission efficiency are given.The influence trend diagram of transmission distance,working frequency,load and other factors on transmission power and transmission efficiency is drawn by using MATLAB.Compare and analyze four typical wireless synchronous transmission modes.Aiming at the shortcomings of AM and FM synchronous transmission technologies,such as discontinuous load supply and offset from resonance frequency,phase modulation synchronous transmission mode is designed and simulated.The results show that phase modulation mode can realize the synchronous transmission of signal and power,and has the advantages of stable load supply and low system loss.In the aspect of coupling coil design,plane helical coil and cylindrical helical coil are designed with HFSS.Then analyze the effects of transmission distance,axial offset and relay coil on transmission characteristics.The electromagnetic radiation characteristics and SAR(specific absorptivity)value produced by coupling coil on human brain are studied.The simulation results show that increasing transmission distance and axial offset will reduce electromagnetic.Increasing the relay coil and magnetic core can increase the electromagnetic field intensity and transmission distance;SAR value and the distance between the coupling coil and human brain are inversely proportional.When the resonance frequency is 300 MHZ,the local SAR peak value of human brain in plane helical coil is 0.0312W/kg,and the average SAR peak value is 0.0158W/kg;the local SAR peak value of human brain in cylinder helical coil is 0.0781W/kg,and the average SAR peak value is 0.0158W/kg.0298W/kg,all within the allowable range of international standards.At the same time,according to the leakage phenomenon of the coupling coil,the method of connecting the cutting coil with capacitance is designed.Through simulation analysis,adding capacitance can improve the magnetic field strength on the coil,reduce the electric field strength,and reduce the SAR value of electromagnetic radiation. |
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