Study On The Structure Design And Performances Of Wide Range Current Sensor

There are currents that vary from zero Hertz to megahertz,from zero amperes to tens of thousands of amperes in mining and metallurgy,rail transit,smart grids,aerospace,and nuclear energy.Accurate measurement and calibration of such wide range current is a major issue concerning personnel safety,economic benefits,energy saving and emission reduction,and scientific and technological breakthroughs.The research of wide range current sensors has become an important indicator to reflect a country’s scientific and technological strength and comprehensive national strength.At present,the technology of wide range current sensors is mainly concentrated in the hands of western developed countries,so it is of great economic value and social benefit to devote to the research of wide range current sensors.Based on the research of magnetic effect of current and magnetic shunt structure,this paper studies the material selection,structure design and performance of wide range current sensors.Ferrites of Li Zn Ti（short for Li Zn Ti）were prepared by solid phase sintering at 1075℃for 3.5 hours.XRD analysis showed that Ti-substituted soft magnetic ferrite of lithium zinc spinel was successfully prepared.SEM analysis showed that the content of Ti significantly affected the morphology characteristics of the grains.The maximum saturation magnetization of Li Zn Ti ferrite is 321.2 k A/m,the Curie temperature Tc is 600℃,and the cutoff frequency reaches 20 MHz.Li Zn Ti Bi ferrite（short for Li Zn Ti Bi）was prepared by adding Bi₂O₃ and B₂O₃ in the ferrite material,using low temperature liquid phase sintering technology at 915℃for 4 hours.The saturation magnetization（Ms）of Li Zn Ti Bi ferrite is as high as 353.1 k A/m,the Curie temperature（Tc）is 300℃,the ferromagnetic resonance linewidth is as low as 181.6 Oe,and and the cutoff frequency reaches 30 MHz.The magnetic core of the current sensor made of Li Zn Ti Bi ferrite can improve the comprehensive performance of the current sensor,such as bandwidth,frequency response characteristics and stability.We have independently developed and packaged high-performance giant magnetoresistance spin sensing chip.After packaging and testing,it is proved that the chip has good linearity,high sensitivity,small hysteresis,wide detection frequency band and bipolar response.The linear range of the chip is-10～10 Oe,operating frequency is DC～15 MHz,the nonlinearity is 0.3～1.5%,electrical offset is-3～3 m V/V,hysteresis is 0.5～1%/FS,and sensitivity is3.2～3.6 m V/Oe.Based on the wide range（wide frequency,wide current）of the current sensor,silicon steel,amorphous and ferrite materials are used to design the magnetic cores for the current sensor,which can test the maximum current of10000A and the frequency covers the low,medium and high frequency.The silicon steel and amorphous magnetic cores have an inner diameter of 140 mm,an outer diameter of 340 mm,and a height of 100 mm.Four air gaps are symmetrically distributed,and each strip is 4 mm wide.The magnetic core of ferrite material has an inner diameter of 140 mm,an outer diameter of 200 mm,and a height of 100 mm.Four air gaps are symmetrically distributed,each with a width of 17 mm.The design scheme of"one system and three structures"for wide range current sensors is proposed.Three kinds of wide range current sensors were designed and manufactured by using three kinds of magnetic cores made of silicon steel,amorphous materials and lithium-zinc ferrite materials and the same set of circuit system.Through the design of a novel multi-sensor fusion unit module,the stability,accuracy and anti-interference ability of sensor testing are greatly improved.performance test of the current sensor was completed.The current test range of the developed wide range current sensor was 0-10000A.he working frequency of the silicon steel core current sensor is DC or power frequency.The ideal working frequency of the amorphous core current sensor is 0-400 k Hz（DC to medium frequency band）,and the ideal working frequency of the ferrite core current sensor is 0-30 MHz（DC to high frequency band）.The sensitivity of the three current sensors is about 61 m V/V/A,the linearity is about 0.6%,and the zero drift is about 0.5V.