CN215005591U - Electromagnetic conversion type optical fiber sensitization current sensing probe - Google Patents
Electromagnetic conversion type optical fiber sensitization current sensing probe Download PDFInfo
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- CN215005591U CN215005591U CN202121099468.2U CN202121099468U CN215005591U CN 215005591 U CN215005591 U CN 215005591U CN 202121099468 U CN202121099468 U CN 202121099468U CN 215005591 U CN215005591 U CN 215005591U
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- magnetostrictive film
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Abstract
The utility model provides an electromagnetic conversion formula optic fibre sensitization current sensing probe, including broadband light source, optic fibre circulator, sensing probe, matching liquid, spectrum appearance and computer, wherein sensing probe includes optic fibre bragg grating, magnetostrictive film, non-ferromagnetic material sleeve pipe and metal solenoid, the utility model discloses a hydrofluoric acid does the corrosion treatment to FBG optic fibre partial envelope, and coat the last layer magnetostrictive film with the magnetron sputtering method, utilize the magnetic effect of electric current and the magnetostrictive characteristic of magnetostrictive film, let in different metal solenoid of the electric current that awaits measuring, produce different magnetic field intensity in non-ferromagnetic material sleeve pipe inside, different magnetic field intensity makes the magnetostrictive film take place the transverse expansion, and then changed the cycle of FBG, make the reflection wavelength peak value drift, realize measuring the electric current high sensitivity that awaits measuring, in addition, the optic fibre end inserts in glycerine matching liquid, partial reflection of the transmitted light wavelength is avoided, so that the measurement accuracy of the current to be measured is not reduced.
Description
Technical Field
The utility model belongs to the technical field of the optical fiber sensing, in particular to electromagnetism conversion formula optic fibre sensitization current sensing probe.
Background
With the acceleration of the marketization process of the power industry, the increasing scale of the power grid and the continuous development of the operation mechanism, the safety and the stability of the operation of the power grid face a severe challenge, and meanwhile, natural disasters and power grid accidents which frequently occur explain the development necessity of the smart power grid, so that the technical requirements on the current sensor which plays an important role in the metering link and the relay protection of the power system are higher and higher. In addition, implementation of 'west electric power transmission from east' is an objective requirement of resource distribution and productivity layout in China, and is an important measure for changing resource advantages of western regions into economic advantages and promoting common development of economy of the western and east regions. In the face of large-current measurement under an extra-high voltage, the traditional electromagnetic sensor faces the problems of high voltage, non-insulation, electromagnetic interference and the like, so that the measurement system is complex in structure and high in cost, and the high-voltage current sensor which is simple in structure, safe, reliable and low in cost becomes a research hotspot. The current sensor based on electromagnetic induction has the problems of magnetic saturation, ferromagnetic resonance, narrow frequency band, small dynamic range, flammability and explosiveness of oil and the like, which are more obvious along with the improvement of voltage level, and the manufacturing cost is more expensive. The optical fiber current sensor has the advantages of good insulativity, electromagnetic interference resistance, wide frequency band and the like, and in recent years, the research progress is very rapid, and the application field is continuously expanded.
The optical fiber sensing technology is used as a component of a smart grid, and can solve problems which cannot be faced by many traditional sensing technologies, so that greater attention should be paid. Compared with the traditional electromagnetic current sensor, the optical fiber current sensor has many characteristics, for example, the optical fiber current sensor can be generally applied to a high-voltage environment; the device can work in a strong electromagnetic interference environment; the device can be applied to a high-speed remote sensing and remote measuring system to achieve the aim of remote monitoring and measurement; also has the advantages of small volume, small mass, low manufacturing cost and the like. However, at present, the faraday magneto-optical effect current sensing scheme is still influenced by the linear birefringence problem of the optical fiber and the ambient temperature factor, and the power supply problem of the high-potential electronic circuit and the reliability problem of the electronic circuit of the photoelectric hybrid solution are not well solved. The advent of fiber bragg gratings may provide an effective solution.
Through research and development in recent years, the FBG sensing technology has become the sensing technology with the highest reliability and the strongest practicability in optical fiber sensing. The method has the advantages of wavelength coding, compatibility with optical fibers, capability of forming a quasi-distributed test system and the like, and is widely applied to strain and temperature measurement of engineering structures. The giant magnetostrictive material is a novel magnetic-mechanical conversion material, has the advantages of large expansion coefficient, high electromechanical coupling coefficient, high response speed and the like, and is widely applied to energy conversion and driving. The invention provides an alternating current sensing method combining a fiber Bragg grating and a magnetostrictive material, which adopts the magnetic effect of current to realize the detection of a variable current signal.
As a passive device having the advantages of high sensitivity, electromagnetic interference resistance, corrosion resistance, no influence of strong light fluctuation, good insulating property and the like, the Fiber Bragg Grating (FBG) is widely introduced in the fields of civil engineering, hydraulic engineering, composite materials, medicine, electric power, aerospace and the like, and remarkable research results are obtained. Because the main component of the optical fiber is SiO2The FBG is fine and fragile, and is easy to damage in practical application, and in order to improve the temperature sensitivity of the fiber grating on the premise of protecting the FBG from being damaged, the fiber grating is generally subjected to cladding treatment by methods such as hydrofluoric acid corrosion and femtosecond laser etching.
The utility model provides a pair of electromagnetism conversion formula optic fibre sensitization current sensing probe utilizes the magnetic effect of electric current, and the different electric current that awaits measuring lets in metal solenoid, and inside ceramic sleeving, produces different magnetic field intensity, different magnetic field intensity makes the magnetostrictive material produce different deformation, influences the grating cycle of FBG, and the drift takes place for the back wave peak value, through the change of peak wavelength, reachs the size of the electric current that awaits measuring. In addition, hydrofluoric acid is used for corroding the cladding of the middle part of the FBG, and a magnetostrictive film is coated on the FBG by a magnetron sputtering method, so that the measurement sensitivity of the current to be measured is improved.
Disclosure of Invention
To the problem mentioned above, the utility model provides an electromagnetic conversion formula optic fibre sensitization current sensing probe's design scheme can realize measuring the high sensitivity of the electric current that awaits measuring.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides an electromagnetism conversion formula optic fibre sensitization current sensing probe, the structure includes broadband light source (1), optic fibre circulator (2), sensing probe (3), matching fluid (4), spectrum appearance (5) and computer (6), its characterized in that: the total length of the sensing probe (3) is 10-15 mm, the sensing probe comprises a fiber Bragg grating (3-1), a magnetostrictive film (3-2), a ceramic sleeve (3-3) and a metal solenoid (3-4), the diameter of a fiber core of the fiber Bragg grating (3-1) is 9 micrometers, the diameter of a cladding is 125 micrometers, the cladding of the fiber Bragg grating (3-1) is subjected to corrosion treatment by using hydrofluoric acid, the diameter of the cladding is corroded to 50 micrometers, the corrosion length is 7mm, a layer of the magnetostrictive film (3-2) is coated on the treated cladding of the fiber Bragg grating (3-1) by a magnetron sputtering method, and the thickness of the magnetostrictive film (3-2) is 30-40 micrometers; the ceramic bushing (3-3) has an inner diameter of 1mm, an outer diameter of 5mm and a length of 10mm, the metal solenoid (3-4) adopts enameled wires wrapping metal copper wires, the enameled wires are tightly and uniformly wound on the ceramic sleeve (3-3), the metal solenoid (3-4) comprises 6 layers in total, the number of turns of each layer is 20 turns, the inner diameter of the metal solenoid (3-4) is 5mm, the outer diameter is 9mm, the fiber Bragg grating (3-1) and the ceramic sleeve (3-3) are respectively fixed on the high-precision optical platform, so that the fiber Bragg grating (3-1) penetrates into the ceramic sleeve (3-3), the magnetostrictive film (3-2) is ensured to be arranged in the central area inside the ceramic sleeve (3-3), and finally the whole sensing probe (3) is packaged.
The electromagnetic conversion type optical fiber sensitization current sensing probe of claim 1, wherein: the metal solenoid (3-4) adopts enameled wires wrapped with metal copper wires, and the diameter of the enameled wires is 0.5 mm.
The strength of the magnetic field generated by the metal solenoid which is closely wound and arranged at the center position of the metal solenoid according to the Biot-Savart law is as follows
In the formula, H is the intensity of the magnetic field intensity generated by the solenoid, namely the intensity of the external magnetic field intensity; n is the number of turns of the coil; l is solenoid length: r is0Is the coil radius.
Under the action of the magnetic field intensity H generated by the solenoid, the relation between the magnetostriction of the magnetostrictive material along the axial direction and the magnetic field intensity is
In the formula: l is the original length of the magnetostrictive film; c coefficient of expansion of magnetostrictive material.
Magnetostriction coefficient C the hysteresis coefficient, which represents the degree of change that occurs in the magnet per unit length along the magnetization direction during magnetization, is given by:
wherein l is the original length of the material; delta l is the change in length of the material after magnetization; generally the magnetostriction coefficient of a magnetostrictive material refers to the measurement along the direction of the magnetic field strength. C is a function of magnetic field intensity and temperature, under a certain temperature, | C | is increased along with the increase of the magnetic field intensity, and when saturated magnetization is achieved, a stable saturation value is achieved, namely a saturation magnetostriction coefficient, and C is usedsAnd (4) showing. For a certain material CsIs a constant.
Coefficient of dynamic magnetostriction d33The dynamic magnetostriction coefficient indicates the sensitivity of the magnetostriction value to the magnetic field strength.
Electromechanical coupling coefficient k33The electromechanical coupling coefficient represents the efficiency of interconversion between magnetic energy and mechanical energy.
In the formula of0Is a vacuum magnetic conductivity; mu.sCIs relative magnetic permeability; eHIs the Young's modulus.
In addition, when a broadband light source is transmitted in the FBG, the current to be measured is not introduced, mode coupling can be generated, and light meeting specific conditions can be reflected:
λB＝2neffΛ
in the formula neffIs the effective refractive index of the Bragg fiber grating, and lambda is the original period of the Bragg fiber gratingBThe center resonant wavelength.
Obtaining the period transformation of the FBG into lambda when the current I to be measured is introduced into the solenoidΔI.e. by
Wherein Δ L is the amount of change in the length of the magnetostrictive film.
When a current I to be measured is introduced into the solenoid, mode coupling is generated, and light meeting specific conditions is reflected:
λΔB＝2neffΛΔ
Δλ＝λΔB-λB
in the formula neffIs the effective refractive index of the Bragg fiber grating, ΛΔIs the original period, lambda, of the Bragg fiber gratingΔBIs the central resonance wavelength, and Δ λ is the central resonance wavelength drift amount.
The sensing probe structure provided by the invention utilizes the magnetic effect of current and the magnetostrictive characteristic of a magnetostrictive film, different metal solenoids of current to be detected are introduced, different magnetic field strengths are generated in a ceramic sleeve, the magnetostrictive film is stretched due to the different magnetic field strengths, the period of the FBG is further changed, and the peak value of the reflection wavelength is shifted, so that the current to be detected is measured, the sensitivity of the sensing probe is improved by removing a cladding and coating the magnetostrictive film, and the high-sensitivity current detection is realized; in addition, the end of the optical fiber is inserted into the glycerol matching fluid, so that the influence of partial reflection of the transmitted light wavelength on the measurement result is avoided.
The method comprises the steps of firstly opening a broadband light source, then introducing different currents to be detected into a metal solenoid, transmitting emitted light to a sensing probe through an optical fiber circulator, generating different magnetic field strengths inside a ceramic sleeve due to the magnetic effect of the current, causing the magnetostrictive film to stretch due to the magnetostrictive effect of the magnetostrictive film, further enabling the period of FBG to change, detecting a reflection wavelength peak value through a spectrometer, finally analyzing through a computer, obtaining the magnetic field strength generated by the current to be detected by detecting the drift amount of the reflection wavelength peak value, and further demodulating the size of the current to be detected.
Drawings
Fig. 1 is a schematic diagram of the detection of an electromagnetic conversion type optical fiber sensitization current sensing probe according to the present invention;
fig. 2 is a schematic structural diagram of an electromagnetic conversion type optical fiber sensitization current sensing probe according to the present invention;
fig. 3 is a transverse cross-sectional view of the electromagnetic conversion type optical fiber sensitization current sensing probe of the present invention.
Detailed Description
The following will further describe the embodiment of the present invention with reference to fig. 2.
The utility model discloses an electromagnetism conversion formula optic fibre sensitization current sensing probe that can survey the electric current, the concrete implementation step is as follows:
the method comprises the following steps: optical fiber grating inscription
Firstly, turning on an argon ion laser, adjusting the light output power to 100mw, and waiting for 5 minutes to stabilize the light output of the laser. And then selecting a single mode fiber with proper length and high germanium content, scraping the coating layer of the single mode fiber by using a wire stripper, cleaning and removing residual scraps in the coating layer area by using alcohol for multiple times, straightening the fiber by using a fiber clamp and ensuring that the fiber is parallel to the phase mask plate and is about 1mm below the mask area. After multiple reflections, the laser forms interference light through a phase mask plate, and finally the one-dimensional displacement platform is controlled by a computer to move at a constant speed, the interference light can enable the optical fiber to be continuously exposed, so that the optical fiber Bragg grating is prepared, and the etching length reaches about 7 mm.
Step two: corrosion treatment of fiber Bragg grating cladding
Taking a fiber Bragg grating with a proper length, fixing the fiber Bragg grating on an optical platform by using a clamp, and removing a cladding of the single-mode fiber by wet etching, wherein a hydrofluoric acid solution with the concentration of 40% is specifically selected. Before corrosion, a piece of polyethylene sheet is fixed on a three-dimensional adjusting frame in the center of an optical platform, a few drops of hydrofluoric acid solution are dropped on the polyethylene sheet, and the hydrofluoric acid solution drops are accurately placed under a single-mode optical fiber by adjusting the three-dimensional adjusting frame. And then lifting the three-dimensional adjusting frame to enable the hydrofluoric acid to immerse the single-mode optical fiber. The size of the specific corrosion area can be controlled by controlling the size of hydrofluoric acid liquid drops and the height of a three-dimensional adjusting frame, the corrosion length is 7mm, and the diameter of the cladding is corroded to 50 mu m.
Step three: coating magnetostrictive films by magnetron sputtering
And taking the fiber Bragg grating with the processed proper length, plating a magnetostrictive film on the corroded cladding of the optical fiber by a magnetron sputtering method, plating the film for four times, adjusting a sample frame after the film plating is finished each time to enable the sensing probe to rotate 90 degrees, and finally achieving the purpose of uniform film plating. The length of the plated film is 7mm, and the thickness of the silver film is 30-40 μm.
Step four: assembly of optical fiber and ferrule
Firstly, respectively placing the processed fiber Bragg grating and the processed ceramic sleeve on two clamps of a three-dimensional adjusting platform, and roughly adjusting the positions of the fiber Bragg grating and the ceramic sleeve to keep the fiber Bragg grating and the ceramic sleeve at the same horizontal height; moving the microscope to the end face of the ceramic sleeve, allowing the end faces of the ceramic sleeve and the processed fiber Bragg grating to be observed at the same time, staying at a distance close to the left end face of the ceramic sleeve, performing fine adjustment alignment, keeping the two dimensions in conformity with each other, such as horizontal dimension, and adjusting the alignment; and finally, slowly inserting the processed fiber Bragg grating structure into the ceramic sleeve until the ceramic sleeve just covers the optical fiber and the magnetostrictive film of the fiber Bragg grating is arranged in the central area inside the ceramic sleeve. The inner diameter of the used ceramic bushing is 1mm, the outer diameter is 5mm, and the length is 10 mm.
Step five: fabrication of solenoid and packaging of sensing probe
The sensing probe is characterized in that an enameled wire wrapping a metal copper wire is uniformly and tightly wound on a ceramic sleeve, the diameter of the enameled wire is 0.5mm, 6 layers of metal copper coils are wound together, the number of turns of each layer is 20, and finally the whole sensing probe is packaged.
Step six: and cleaning and airing the whole sensing probe.
The basic principle of the utility model is that: according to the sensing probe structure, different metal solenoids of current to be detected are introduced by utilizing the magnetic effect of the current and the magnetostrictive characteristic of a magnetostrictive film, different magnetic field strengths are generated inside a ceramic sleeve, the magnetostrictive film is stretched by the different magnetic field strengths, the period of an FBG is further changed, and the reflection wavelength peak value of the FBG is shifted, so that the current to be detected is measured, the sensitivity of the sensing probe is improved by removing a cladding layer and coating the magnetostrictive film, and high-sensitivity current detection is realized; in addition, the tail end of the optical fiber is inserted into the glycerol matching fluid, so that partial reflection of the wavelength of the transmitted light is avoided, and the measurement accuracy of the current to be measured is prevented from being reduced.
Claims (2)
1. The utility model provides an electromagnetism conversion formula optic fibre sensitization current sensing probe, the structure includes broadband light source (1), optic fibre circulator (2), sensing probe (3), matching fluid (4), spectrum appearance (5) and computer (6), its characterized in that: the total length of the sensing probe (3) is 10-15 mm, the sensing probe comprises a fiber Bragg grating (3-1), a magnetostrictive film (3-2), a ceramic sleeve (3-3) and a metal solenoid (3-4), the diameter of a fiber core of the fiber Bragg grating (3-1) is 9 micrometers, the diameter of a cladding is 125 micrometers, the cladding of the fiber Bragg grating (3-1) is subjected to corrosion treatment by using hydrofluoric acid, the diameter of the cladding is corroded to 50 micrometers, the corrosion length is 7mm, a layer of the magnetostrictive film (3-2) is coated on the treated cladding of the fiber Bragg grating (3-1) by a magnetron sputtering method, and the thickness of the magnetostrictive film (3-2) is 30-40 micrometers; the ceramic bushing (3-3) has an inner diameter of 1mm, an outer diameter of 5mm and a length of 10mm, the metal solenoid (3-4) adopts enameled wires wrapping metal copper wires, the enameled wires are tightly and uniformly wound on the ceramic sleeve (3-3), the metal solenoid (3-4) comprises 6 layers in total, the number of turns of each layer is 20 turns, the inner diameter of the metal solenoid (3-4) is 5mm, the outer diameter is 9mm, the fiber Bragg grating (3-1) and the ceramic sleeve (3-3) are respectively fixed on the high-precision optical platform, so that the fiber Bragg grating (3-1) penetrates into the ceramic sleeve (3-3), the magnetostrictive film (3-2) is ensured to be arranged in the central area inside the ceramic sleeve (3-3), and finally the whole sensing probe (3) is packaged.
2. The electromagnetic conversion type optical fiber sensitization current sensing probe of claim 1, wherein: the metal solenoid (3-4) adopts enameled wires wrapped with metal copper wires, and the diameter of the enameled wires is 0.5 mm.
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| CN202121099468.2U CN215005591U (en) | 2021-05-21 | 2021-05-21 | Electromagnetic conversion type optical fiber sensitization current sensing probe |
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Granted publication date: 20211203 |