Research On Key Technology Of Magnetic Components Of Controlled Source Electromagnetic Transmission

With the development of our social economy， the demand for ore resources inall walks of life is increasing day by day. Along with the increase of mining strength，shallow ore is exhausted and becomes the crisis mines. As a consequence of this，exploration of deep concealed ore should be valued gradually. With the strong signaland the capacity of resisting disturbance， the Controlled Source Audio-frequencyMagnetotelluric(CSAMT) has been widely used. This method needs high-powerelectrical source transmitter as emission source. Traditional liner regulated powersupply has large power consumption when it is used in large current and high poweroutput condition. So its efficiency is low and heat dissipation is poor. As the industrialfrequency transformer has big volume and weight， high efficiency switching powersupply solves this problem. At present， geophysical instruments has made greatprogress in our country. But for the deep prospecting， the requirement for transmitterpower is higher. As a result of this， design and product the electrical sourcetransmitter meets the requirements is particularly important.Switching power supply has much smaller volume and weight， while itsefficiency has improved a lot. In switching power supply， power magnetics，including transformer，inductor and EMI filter，are core components. They have thefunction of magnetic energy transmission， storage， filter and suppresselectromagnetic interference. Power magnetics are different from other electroniccomponents. As it is difficult to buy the magnetics meet the requirements in themarket， most of them need to be designed by ourselves. Therefore， the design andmanufacture of magnetic components plays an important role to the success of switch power supply design.This paper based on national potential oil and gas resources (development andutilization of oil shale exploration) study in collaborative innovation project Oil shaleresources geophysical detection of key technology and equipment. According totechnical indexes of high-power electrical source emission system requirements，designing power transformer， inductor and three-phase EMI filter.In view of the high power electrical source transmitter technical indexrequirements， design flow of high-power and high-frequency transformer based onarea multiply is proposed. According to the deduction and analysis of waveformfactor， magnetic core shape， magnetic core material and core losses， powertransformer meets the requirements is designed. Magnetic core skeleton is designedbased on the structure parameter and the number of parallel magnetic cores.According to high power electrical source transmitter technical indexrequirements， design flow of air-gap inductor is proposed. The reason that inductorneeds air gap is explained. Several common strategy of air gap is compared. Optimalmethod of air gap is chosen. In view of the length of air gap the inductor is redesigned.Optimal solution is got by it.In order to suppress the three-phase electromagnetic interference (EMI) ofswitching power supply to inject into the power grid， the design method ofthree-phase EMI filter is proposed. By modeling and analyzing the three-phasecommon-mode inductance， the ideal equivalent circuits of common-mode anddifferential-mode filters are built. The effects of high frequency on ideal equivalentcircuits are analyzed. The insertion loss expression based on parameter matrix isdetermined. Parameter matrixes of common-mode and differential-mode filters arederived in ideal and high frequency condition. According to the character of loadimpedance in power grid side and source impedance in switching power supply side，the relationship between insertion loss and frequency is analyzed. Because highconductivity of soft magnetic ferrite has gyromagnetic frequency limit and nonlinearhysteresis loop， the inhibitory effect on common-mode inductance and influence oncommon-mode insertion loss by them are analyzed. The filter’s parameters are determined based on the related suppress standards and requirements.This article finally tests on the transformer， inductor and EMI filter.Experimental result is analyzed. According to the deficiency of existing magneticcomponents， recommendations for improvement are proposed.