| After the second industrial revolution,the age of electricity had come.With the development of science and technology,a large number of electrical equipment is entering people's lives.Cable power transmission shows a lot of drawbacks.Magnetically-coupled Resonant Wireless Power Transfer(WPT)has instantly become a hot research topic at home and abroad since it was first proposed by MIT in 2007.A deep study of its principle,circuit topology and transmission performance has been made by the experts and scholars.As the medium of energy transmission,the distribution of magnetic field in space is of great significance to the further study of Magnetically-coupled Resonant WPT.Currently,there have been some magnetic field measurement instruments on the market.Most of them are relatively large size and narrow frequency range.The measuring instrument is suitable for measuring the space magnetic field of the Magnetically-coupled Resonant WPT system,which is very few and expensive.Therefore,it is of great practical significance to realize the measurement of the magnetic field in the WPT.In this paper,a set of magnetic field measurement system is developed,including the design and manufacture of 3D magnetic field probe,the research of data acquisition system and the design of the measuring scheme.Magnetic induction intensity in fixed frequency points are measured.The measured results are drawn into a three-dimensional map,and the results are compared with the simulation results.It is concluded that the measurement system can provide powerful help for the study of Wireless Power Transfer.Firsyly,we introduce the Maxwell equations of the electromagnetic field,the law of electromagnetic induction is analyzed in detail.By analyzing the electromagnetic field properties of the unit dipole antenna,the division of the near field and far field of the unit dipole antenna and the electromagnetic field properties of them are analyzed.The characteristics of the near field measurement are summarized and the basic characteristics of the WPT transmission theory are analyzed.Secondly,the principle of one dimensional magnetic field probe is analyzed in detail.The transfer function and the size of the coil are deduced.The validity of the theoretical derivation is verified by simulation and a one-dimensional magnetic field probe is made.On the basis of onedimension magnetic field probe,the model of 3D magnetic field probe is designed and three dimensional magnetic field probe is made.Then,the hardware and software parts of the three-channel data acquisition system are researched.The hardware circuit describes the high-frequency amplifier circuit module,the FPGA peripheral circuit(including the power supply circuit,the clock circuit,the USB serial port,the expansion port,etc.),the A/D Conversion module,the software part of the data acquisition,data communication and PC data storage were analyzed.Finally,the basic unit of the magnetic resonance radio transmission(ie,only the case of the excitation coil)and the two coil systems with both the transmitting coil and the receiving coil are measured respectively.The measured results are plotted as a three-dimensional map of the magnetic induction intensity distribution.The corresponding simulation model is built in Maxwell 3D,and the corresponding comparative analysis is carried out.The measurement results are in good agreement with the simulation results in the trend and the error is small in the magnetic field strength of the local. |
PDF Full Text Request