Resonant Wireless Power Transmission Technology For Different Transmission Distances

With the development of science and technology,research on wireless power transmission technology has received extensive attention from scholars at home and abroad in recent years.Compared with the traditional power transmission system,the wireless power transmission system has the technical advantages of high security and reliability,and is flexible and convenient to use,and is also suitable for some special use scenarios.With the rapid development of electronic information technology,the wide application of mobile electronic communication equipment and wearable devices,the continuous popularization of new energy vehicles and rail transit,wireless power transmission technology has broad application prospects.Compared with other types of wireless power transmission technology,magnetic resonance wireless power transmission technology has the characteristics of high transmission efficiency and long transmission distance,making it the most popular research direction in the current wireless power transmission technology.In this paper,three kinds of resonant wireless power transmission technologies with different transmission distances are studied,focusing on the improvement of system efficiency.On the basis of introducing the basic concepts and related theories,the main contents are the analysis and design of transmission coil loop,front-end power amplifier and adaptive impedance matching circuit.The specific work is as follows:?1?The resonant coil loop is composed of a planar microstrip coil structure and a capacitance matching network,which is equivalent to a two-port network.The transmission efficiency is effectively evaluated by usingS₂₁ parameters.CST software is used to model and simulate the coil circuit with the size of 20 cm*20 cm.Under the condition of 6.78 MHz resonance frequency,the matched capacitance values of 8 cm,10 cm and 12 cm transmission distances are obtained respectively,which make the S₂₁ parameter optimal.The coil circuit is tested experimentally.With 1V as the reference standard,the S₂₁ peaks between the two ports of the transmission coil circuit at 8cm,10cm and 12cm are 937mV,923mV and 885mV.?2?On the basis of introducing the basic classification and comparison of front-end power amplifiers,the class E power amplifier is selected as the high frequency power supply of magnetic resonance wireless power transmission system and the correlation analysis is made.According to the classical calculation formula,the related parameters of class E power amplifier circuit are obtained.The ADS software is used to simulate and design.The additional power efficiency is 81.2%at 6.78MHz through further circuit debugging and optimization.The efficiency of cascaded class E power amplifier,transmission coil and rectifier module is tested at three distances.The system efficiency of 8cm,10cm and 12cm is 61.3%,57.1%and 50.8%,respectively.?3?According to the characteristics of the transmission coil circuit in this paper,the design and verification of the adaptive impedance matching circuit under three transmission distances are carried out.A scheme of correlative adaptive impedance matching circuit is proposed,and the design of coil circuit with matched capacitor array is introduced.By comparing the module selection schemes of the adaptive circuit,the function of the selected unit circuit module is introduced.Proteus software is used to simulate and verify the adaptive impedance matching circuit,and relevant circuits are built for testing.The function of accurately switching capacitor array circuit when the distance changes is realized,and the correctness of theoretical analysis is verified.