Research On Characteristics Of Magnetic Resonance Coupling Wireless Power Transfer Systems

In2007, magnetic resonance coupling wireless power transfer technology was put forward by the Massachusetts institute of technology’s scientist, the technology overcome the inherent shortcomings of the microwave energy transfer and inductively coupled power transfer technology, and has become a research focus. Magnetically-coupled resonant wireless power transfer technology can efficiently deliver energy in meters level, and is not affected by non-magnetic materials around. After years of research, magnetically-coupled resonant wireless power transfer technology has made considerable progress, the theoretical analysis and experimental research methods are continually improving, but there are still gaps from practical application. This paper made a detailed analysis of the coupling coil and high frequency power supply in system, the details are as follows:(1) Introduces the basic structure and working principle and circuit model of the resonant wireless power transfer system in detail. Coil magnetic field can be divided into near-field and far-field region by the near-field theory, and pointed out that the system transmission in near-field range; expounds the wireless power transmission process follows principles and equations; Finally obtained system efficient working conditions are the two coupling coil with the same intrinsic frequency by coupled-mode theory. When two coupling coil has a larger coupling coefficient, the operation of the system frequency and the coil eigen frequency difference. Through the circuit model of the two-coils and four-coils model, obtain the expression of the system parameters and transmission power and transmission efficiency.(2) The optimize design of the coupling coil in resonant wireless power transfer system. Based on the equivalent circuit model to design and production of a wireless power transmission device, the accuracy of the formula is derived through experiments; the research indicates that the mutual inductance of the four-coil structure has a significant effect on the system transmission performance, by adjusting the mutual inductance between the power coil and transmitter coil, load coil and receiving coil, can make the system’s load adaptability and transmission distance get obvious optimization; This paper points out that there is frequency splitting phenomenon when transmission distance is close, at this point the frequency tracking technology can make the system transmission performance is optimized; finally by adding repeating coil effectively increase the transmission distance of the system.(3) Design and analysis of high frequency power supply. Firstly expounds the working principle and parameter’s design steps of class E amplifier circuit, and introduced the requirements of switch tube, the design of the driving circuit and components selection, then the simulation was performed by Capture CIS, at last, through experiments to test and verify, by adding a magnetic ring transformer, can effectively solve the problem that parameters are difficult to match between power supply module and wireless power transfer modules, the experimental results show that the design of class E amplifier circuit in this paper can output the power of17.69W, and transfer efficiency up to88.45%.