CN203587784U - FBG (Fiber Bragg Grating) magnetic field sensor based on current heat effect - Google Patents

FBG (Fiber Bragg Grating) magnetic field sensor based on current heat effect Download PDF

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CN203587784U
CN203587784U CN201320748569.7U CN201320748569U CN203587784U CN 203587784 U CN203587784 U CN 203587784U CN 201320748569 U CN201320748569 U CN 201320748569U CN 203587784 U CN203587784 U CN 203587784U
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optical fiber
magnetic field
fiber bragg
fbg
commutator
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李川
赵成均
陈富云
王敏吉
庄君刚
赵振刚
谢涛
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Kunming University of Science and Technology
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Kunming University of Science and Technology
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Abstract

The utility model relates to an FBG magnetic field sensor based on the current heat effect, belonging to the technical field of photoelectron measurement. The FBG magnetic field sensor comprises a dc asynchronous motor, a motor shaft, a commutator, a brush, a rectangular coil, bridge type rectifier diodes, a filtering capacitor, a variable resistor, an FBG, a constantan piece, teflon and external leading-out fibers, wherein the dc asynchronous motor, the motor rotor, the commutator and the rectangular coil are fixed, the brush makes contact with the commutator, a contact of the brush is connected with the bridge type rectifier diodes, the leading-out end of each bridge type rectifier diodes is connected to both the filtering capacitor and the variable resistor, and the FBG is adhered to the constantan piece via the teflon, and connected to the external leading-out fibers. According to the utility model, the measuring range for the magnetic field and the measuring flexibility of the sensor can be adjusted, the resistance does not change with temperature, and the FBG magnetic field sensor is strong in the anti-interference capability, simple in structure and convenient to use.

Description

A kind of optical fiber Bragg raster magnetic field sensor based on heating effect of current
Technical field
The utility model relates to a kind of optical fiber Bragg raster magnetic field sensor based on heating effect of current, belongs to photoelectron field of measuring technique.
Background technology
Many fields in commercial production and scientific research all will relate to magnetic-field measurement problem, as magnetic mine locating, geologic prospecting, magnetic material research, magnetic navigation, isotopic number separation, controlled thermonuclear reaction and artificial earth satellite etc.Along with the development of high voltage direct current power transmission and transformation, the monitoring of the surrounding magnetic fields such as transformer station, high voltage transmission line has great significance for the safe operation of electrical network.For this reason, the optical fiber Bragg raster magnetic field sensor of electrical isolation, anti-electromagnetic interference (EMI), all optical communication becomes one, magnetic field detection field important research direction.
With the approaching detection technique of the utility model patent be that optical fiber grating temperature current-sensing and measurement mechanism thereof are (referring to patent, patent publication No.: CN 101033990A), this patent of invention is to consist of fiber grating and solenoid, fiber grating surface is provided with metallic conductor, due to exchange current eddy-current heating on metallic conductor, by the detection of transformation temperature, can only realize the measurement to alternating current.Because faraday's electromagnetic induction phenomenon is that the magnetic field changing produces electric field, therefore adopt solenoid structure, can only be the measurement realizing variation magnetic field, the utility model design adopts coil cutting, can realize the measurement to uniform magnetic field.
Also need to consider the formation of optical fiber Bragg raster magnetic field sensor simultaneously, and how to install to realize the protection problem to optical fiber while measuring.
Summary of the invention
The utility model provides a kind of optical fiber Bragg raster magnetic field sensor based on heating effect of current, for solving structure, the installation question of optical fiber Bragg raster magnetic field sensor.
The technical solution of the utility model is: a kind of optical fiber Bragg raster magnetic field sensor based on heating effect of current, comprises DC asynchronous motor 1, machine shaft 2, commutator 3, brush 4, square coil 5, bridge rectifier diode 6, filter capacitor 7, variable resistor 8, optical fiber Bragg raster 9, constantan sheet 10, teflon 11, the external optical fiber 12 of drawing; Wherein DC asynchronous motor 1, machine shaft 2, commutator 3 and square coil 5 are fixed together, brush 4 contacts with commutator 3 and the contact of brush 4 is connected with bridge rectifier diode 6 by wire, the exit of bridge rectifier diode 6 is connected with filter capacitor 7, variable resistor 8, optical fiber Bragg raster 9 is bonded on constantan sheet 10 by teflon 11, and is connected with the external optical fiber 12 of drawing.
On described constantan sheet 10, cut out rectangle square groove, wherein in rectangle square groove, place optical fiber Bragg raster 9.
Principle of work of the present utility model is:
Machine shaft 2 by DC asynchronous motor 1 drives square coil 5 cutting magnetic fields, there is electromagnetic induction phenomenon, by commutator 3 and brush 4, according to DC asynchronous motor 1 internal electromagnetic principle of induction, convert magnetic field energy to electric energy, the voltage producing passes through wire, rectification through bridge rectifier diode 6, the filtering of filter capacitor 7, by variable resistor 8, the voltage end of wire output is connected on constantan sheet 10, according to the thermal effect principle of electric current, realized the conversion between electric energy and heat energy, when the temperature on constantan sheet 10 changes, can make the centre wavelength of the optical fiber Bragg raster 9 on bonding constantan sheet 10 be shifted, by carrying out Real-Time Monitoring to the electric current by constantan sheet 9 to the measurement of optical fiber Bragg raster 9 wavelength-shifts, and then can obtain filtered magnitude of voltage, according to the mathematical model of Dyn. internal electromagnetic principle of induction and bridge rectifier circuit, by the conversion of voltage and magnetic field intensity relation, can carry out Real-Time Monitoring to magnetic field.
Mathematics model analysis of the present utility model is as follows:
Due in pure resistor element circuit, the equilibrium relation of current work is:
Figure 2013207485697100002DEST_PATH_IMAGE002
(1)
In formula, ifor the size of current to the energising of constantan sheet, rfor the resistance of constantan sheet, tfor constantan sheet is led to the electrically heated time, ufor the institute's making alive size on constantan sheet.
According to Dyn. internal electromagnetic principle of induction, can obtain unidirectional magnetic field with induced voltage
Figure DEST_PATH_IMAGE006
relation:
U= NBSW (2)
In formula, nfor the number of turn of square coil, sfor the cross-sectional area of square coil, wangular velocity for square coil rotation.
Through bridge rectifier circuit rectification, after capacitor filtering, can obtain the size in magnetic field bwith induced voltage urelation:
(3)
Wushu (3) substitution formula (1), according to the heat transmission of electric current, just can obtain the size of electric current iwith magnetic field size bbetween relation:
Figure DEST_PATH_IMAGE010
(4)
According to the thermal effect of electric current, the heat energy of current work and generation closes and is:
I 2 Rt= CmΔ T (5)
In formula, ifor the size of current to the energising of constantan sheet, rfor the resistance of constantan sheet, tfor constantan sheet is led to the electrically heated time, cfor the specific heat capacity of constantan sheet, mfor the quality of constantan sheet, Δ tvariable quantity for constantan sheet surface temperature.
Wushu (4) substitution formula (5), can obtain the variation delta of temperature tsize with institute's measuring magnetic field bbetween relation:
Figure DEST_PATH_IMAGE012
(6)
The peak wavelength reflecting due to optical fiber Bragg raster meets:
(7)
In formula,
Figure DEST_PATH_IMAGE016
for the centre wavelength of optical fiber Bragg raster, n eff effective refractive index, it is the grating cycle.
(7) formula is carried out to temperature tdifferentiate can obtain:
Figure DEST_PATH_IMAGE020
(8)
In formula,
Figure DEST_PATH_IMAGE022
it is the originally elastic deformation under effect of stress of optical fiber; Δ n eff it is the elasto-optical effect of optical fiber.
(8) formula both sides, divided by (7) formula, can obtain:
(9)
In formula, s t for the temperature coefficient of sensor,
Figure DEST_PATH_IMAGE026
for the variation of wavelength, αfor the thermal expansivity of optical fiber, ξthermo-optical coeffecient for optical fiber.
Wushu (6) substitution formula (9), can obtain the wavelength-shift amount of fiber grating
Figure DEST_PATH_IMAGE028
size with magnetic field
Figure 169231DEST_PATH_IMAGE004
between relation:
(10)
Formula (10) has shown the magnetic field size of magnetic field sensor actual measurement and the mathematical model between the Bragg wavelength-shift of optical fiber Bragg raster, can calculate the size in actual measurement magnetic field by the Bragg wavelength-shift amount of measuring optical fiber Bragg grating.
The beneficial effects of the utility model are:
1, by variable-resistance resistance adjustment, can regulate the measurement range size in magnetic field and the measurement sensitivity of sensor.
2, the constantan sheet of selecting, has lower temperature-coefficient of electrical resistance, wider temperature usable range, and its resistance can variation with temperature and is changed.
3, through bridge rectifier circuit, make the voltage of output more level and smooth, according to the charge-discharge characteristic of filter capacitor, reduce pulsation composition.
4, for the thermal effect of electric current, consider temperature variation and the sensitivity level to temperature on constantan sheet, the measurement of the DC current after overcommutation is more prone to realize than AC measurment, more can directly reflect real-time size of current, and then more can reflect in real time the size in magnetic field.
5, antijamming capability is strong: adopt electrically insulating material optical fiber Bragg raster, signal transmission is light signal, can resist electromagnetic interference (EMI), meanwhile, reduces in addition the ignite effect of inflammable gas gas to be measured of electric spark, has reduced potential safety hazard.Optical fiber Bragg grating sensor is applicable to exist under the special operation condition in electromagnetic interference (EMI) situation and measures in real time.
6, simple in structure, easy to use.
Accompanying drawing explanation
Fig. 1 is structural representation of the present utility model;
Each label in figure: 1 is that DC asynchronous motor, 2 is that machine shaft, 3 is that commutator, 4 is that brush, 5 is that square coil, 6 is that bridge rectifier diode, 7 is that filter capacitor, 8 is that variable resistor, 9 is that optical fiber Bragg raster, 10 is that constantan sheet, 11 is that teflon, 12 is the external optical fiber of drawing.
Embodiment
Embodiment 1: as shown in Figure 1, an optical fiber Bragg raster magnetic field sensor based on heating effect of current, comprises DC asynchronous motor 1, machine shaft 2, commutator 3, brush 4, square coil 5, bridge rectifier diode 6, filter capacitor 7, variable resistor 8, optical fiber Bragg raster 9, constantan sheet 10, teflon 11, the external optical fiber 12 of drawing; Wherein DC asynchronous motor 1, machine shaft 2, commutator 3 and square coil 5 are fixed together, brush 4 contacts with commutator 3 and the contact of brush 4 is connected with bridge rectifier diode 6 by wire, the exit of bridge rectifier diode 6 is connected with filter capacitor 7, variable resistor 8, optical fiber Bragg raster 9 is bonded on constantan sheet 10 by teflon 11, and is connected with the external optical fiber 12 of drawing.
On described constantan sheet 10, cut out rectangle square groove, wherein in rectangle square groove, place optical fiber Bragg raster 9.
Embodiment 2: as shown in Figure 1, an optical fiber Bragg raster magnetic field sensor based on heating effect of current, comprises DC asynchronous motor 1, machine shaft 2, commutator 3, brush 4, square coil 5, bridge rectifier diode 6, filter capacitor 7, variable resistor 8, optical fiber Bragg raster 9, constantan sheet 10, teflon 11, the external optical fiber 12 of drawing; Wherein DC asynchronous motor 1, machine shaft 2, commutator 3 and square coil 5 are fixed together, brush 4 contacts with commutator 3 and the contact of brush 4 is connected with bridge rectifier diode 6 by wire, the exit of bridge rectifier diode 6 is connected with filter capacitor 7, variable resistor 8, optical fiber Bragg raster 9 is bonded on constantan sheet 10 by teflon 11, and is connected with the external optical fiber 12 of drawing.
On described constantan sheet 10, cut out rectangle square groove, wherein in rectangle square groove, place optical fiber Bragg raster 9.
Concrete implementation step is:
The driving voltage of the DC asynchronous motor of 1, selecting u=12V, rotating speed n=3000r/min, frequency is 50Hz, revolves the time used of turning around desirable t=0.02s;
2, square coil is selected: square coil is selected copper cash saw lumber, resistivity
Figure DEST_PATH_IMAGE032
, long a=20cm, wide b=10cm, the number of turn n=10, the cross-sectional area of square coil s=20 * 10cm 2, the angular velocity of coil rotation w=2 π/ t=2 π n, will n=3000r/min substitution, w=100 π rad/s;
3, choosing of commutation diode: select 1N5402 silicon rectifier diode, repetitive peak reverse voltage is
Figure DEST_PATH_IMAGE034
, the average commutated current of forward is i=3.0A;
4, the reactive power loss of considering circuit, filter capacitor is chosen
Figure DEST_PATH_IMAGE036
;
5, the maximum of considering square coil copper cash and commutation diode is born electric current and voltage, chooses the resistance of access protective resistance
Figure DEST_PATH_IMAGE038
;
6, constantan sheet is selected: length is 10cm, wide 2cm, and high 5mm, resistivity is ρ=0.0175 Ω .mm2/m, the resistance of constantan sheet r=1.75 * 10 -5, because the density of copper is 8.9g/cm 3, the quality of constantan sheet is m=89g, specific heat capacity is c=0.39J/g. ℃;
7, optical fiber Bragg raster technical parameter: centre wavelength
Figure DEST_PATH_IMAGE040
nm, valid round backscatter extinction logarithmic ratio p e =0.22, the thermal expansivity of optical fiber α=0.8 * 10 -6-1, the thermo-optical coeffecient of optical fiber ξ=6.0 * 10 -6-1;
8, measuring sensor fibre effective length gets l=100mm;
9, press accompanying drawing 1 configuration experiment;
10, with optical fiber Bragg raster (FBG) demodulator, obtain the wavelength value of optical fiber Bragg raster;
11, according to formula
Figure 460885DEST_PATH_IMAGE030
can obtain the size in magnetic field of magnetic field sensor actual measurement and the relation between the Bragg wavelength-shift of optical fiber Bragg raster;
12, by the centre wavelength of optical fiber Bragg raster, valid round backscatter extinction logarithmic ratio, the number of turn of square coil, area, the angular velocity of rotating shaft, sensor fibre effective length, formula in the design parameter substitution steps 11 such as the specific heat capacity of constantan sheet, resistance and quality, the pressure bearing due to fiber grating is 3000 , so the maximum magnitude that grating wavelength can change is
Figure DEST_PATH_IMAGE044
, theory is calculated and is shown, and at 0.02s, in the time, when the wavelength resolution of optical fiber Bragg raster (FBG) demodulator is 1pm, the resolving power of this sensor is 0.4mT, can realize magnetic-field measurement maximum magnitude at 0.4mT ~ 1.096T;
13, through bridge rectifier circuit, make the voltage of output more level and smooth, according to the charge-discharge characteristic of filter capacitor, reduce pulsation composition.
By reference to the accompanying drawings embodiment of the present utility model is explained in detail above, but the utility model is not limited to above-mentioned embodiment, in the ken possessing those of ordinary skills, can also under the prerequisite that does not depart from the utility model aim, make various variations.

Claims (2)

1. the optical fiber Bragg raster magnetic field sensor based on heating effect of current, is characterized in that: comprise DC asynchronous motor (1), machine shaft (2), commutator (3), brush (4), square coil (5), bridge rectifier diode (6), filter capacitor (7), variable resistor (8), optical fiber Bragg raster (9), constantan sheet (10), teflon (11), the external optical fiber (12) of drawing; Wherein DC asynchronous motor (1), machine shaft (2), commutator (3) and square coil (5) are fixed together, brush (4) contacts with commutator (3) and the contact of brush (4) is connected with bridge rectifier diode (6) by wire, the exit of bridge rectifier diode (6) is connected with filter capacitor (7), variable resistor (8), it is upper that optical fiber Bragg raster (9) is bonded in constantan sheet (10) by teflon (11), and be connected with the external optical fiber (12) of drawing.
2. the optical fiber Bragg raster magnetic field sensor based on heating effect of current according to claim 1, is characterized in that: on described constantan sheet (10), cut out rectangle square groove, wherein in rectangle square groove, place optical fiber Bragg raster (9).
CN201320748569.7U 2013-11-25 2013-11-25 FBG (Fiber Bragg Grating) magnetic field sensor based on current heat effect Expired - Fee Related CN203587784U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103645446A (en) * 2013-11-25 2014-03-19 昆明理工大学 A fiber Bragg raster magnetic field sensor based on a current heat effect and an application method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103645446A (en) * 2013-11-25 2014-03-19 昆明理工大学 A fiber Bragg raster magnetic field sensor based on a current heat effect and an application method thereof
CN103645446B (en) * 2013-11-25 2017-04-12 昆明理工大学 A fiber Bragg raster magnetic field sensor based on a current heat effect and an application method thereof

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