A kind of all-fiber current transformator
Technical field
The utility model relates to a kind of optical fiber type current mutual inductor, specifically a kind of all-fiber current transformator.
Background technology
Current measurement is one of basic demand of the normal operation of electric system.At present, the current measuring device that generally adopts of electric system is traditional electromagnetic current transducer.Along with the raising of electric system current class, the defective of traditional electromagnetic current transducer for example is subject to electromagnetic interference (EMI), insulation system complexity, cost height, exists magnetic saturation and ferroresonance phenomenon etc. to become increasingly conspicuous.And the fiber-optic current measuring device has advantages such as anti-electromagnetic interference (EMI), insulating capacity is strong, volume is little, cost is low, has the unrivaled advantage of traditional electromagnetic current transducer.The fiber-optic current measuring device has been launched development research widely both at home and abroad in recent decades.But this type optical fiber current measuring device generally all is based on the electrooptical effect principle of polarizing modulation, and more serious temperature effect is arranged, and the temperature stability of system is poor.
All-fiber current transformator is the current sensor of a kind of functional form, phase modulation (PM).With respect to tradition based on electromagnetic induction principle, it is based on magneto-optic faraday effect principle, adopt optical fiber as sensor information, do not exist ferromagnetic resonance and magnetic to saturated hidden danger, have bandwidth simultaneously, dynamic range is big, accuracy of detection is high, volume is little, in light weight, environmental adaptability good, and series of advantages such as manufacturing and maintenance cost be low.
Summary of the invention
In order to solve the deficiencies in the prior art, the utility model provides a kind of all-fiber current transformator.
The purpose of this utility model is achieved in that a kind of all-fiber current transformator, is made up of light source, Optical Receivers, analog to digital converter, digital demodulator, microprocessor, modulating driver, Y branch integrated optics phase-modulator, fiber coupler, guarantor's off-delay optical fiber, polarization-maintaining fiber coupler, λ/4 delayers, sensor fibre and catoptron.Its architectural feature is as follows: light source links to each other with the first input end of fiber coupler, second input end of Optical Receivers and fiber coupler links to each other, Optical Receivers, digital quantizer, digital demodulator, microprocessor link to each other successively, fiber coupler links to each other with Y branch integrated optics phase-modulator, and digital demodulator links to each other with Y branch integrated optics phase-modulator by modulating driver; Two input ends of Y branch integrated optics phase-modulator link to each other with two input ends of polarization-maintaining coupler with polarization maintaining optical fibre by protecting off-delay optical fiber respectively, one of them output terminal of polarization-maintaining coupler links to each other by polarization maintaining optical fibre with λ/4 delayers, from being wrapped on the tested current lead at the sensor fibre that λ/4 delayers pick out, the end of sensor fibre is installed a catoptron.
Y branch integrated optics phase-modulator is by a polarizer, a splitter and an optical phase modulator composition, the polarizer is divided into the linearly polarized light signal of two quadratures with light signal, and transmits along the x axle and the Y-axis of optical fiber respectively.The luminous power of described splitter is divided equally, and promptly its luminous power splitting ratio is 1: I.The birefringent characteristic that described optical phase modulator utilizes optical fiber carries out synchronous modulation to the linearly polarized light of two quadratures, and modulation signal is from modulating driver.Behind the input light input Y branch integrated optics phase-modulator, the polarizer of Y branch integrated optics phase-modulator inside is converted into input optical signal the linearly polarized light of x and two patterns of y, the Y splitter is divided into two-way output with linearly polarized light, two-way output light enters phase-modulator, one of its y branch waveguide is used for the offset signal modulation, another is used for the feedback signal phase modulation (PM), forms the closed loop monitoring so that the feedback phase shift to be provided.
The novel course of work of this use is: the light of light source enters Y branch integrated optics phase-modulator through fiber coupler, and Y branch integrated optics phase-modulator is exported the linearly polarized light that input optical signal carries out being divided into after the phase modulation (PM) x and two patterns of y simultaneously by the two-way output terminal; This light phase modulation signal carries out synchronous modulation according to the modulation signal from digital demodulator to the orthogonalized linearly polarized light of two-way, first output terminal of Y branch integrated optics phase-modulator is through protecting the first input end of off-delay optical fiber input polarization-maintaining fiber coupler then, second output terminal of Y branch integrated optics phase-modulator is through second input end of polarization maintaining optical fibre input polarization-maintaining fiber coupler, and the arbitrary output terminal output x of polarization-maintaining fiber coupler and the linearly polarized light of two patterns of y transfer to λ/4 delayers; At λ/4 delayer places, two bunch polarisations are converted into left-handed rotatory polarization and dextrorotation rotatory polarization respectively, advance people's sensor fibre; Two light beams run into catoptron propagating when reaching home in the sensor fibre of lead, light returns along same path.Electric current in the lead is because Faraday effect produces magnetic field, when the light in the optical fiber during around wire spread, because the effect in magnetic field makes that the transmission speed of dextrorotation rotatory polarization and left-handed rotatory polarization is different, differ thereby form, when two bundle rotatory polarizations are transferred to the sensor fibre end, direct reflection takes place, two bundle rotatory polarizations are in the left-handed change dextrorotation of modes swap, dextrorotation becomes left-handed back and returns along original optical path, effect doubles, and the linearly polarized light patterns that change two bundle orthogonal modes at λ/4 delayer places once more into have also been exchanged.
The path of walking according to above-mentioned described light is:
(1) Y branch integrated optics phase-modulator-Bao off-delay optical fiber-polarization-maintaining fiber coupler-λ/4 delayers-sensor fibre-catoptron-sensor fibre-λ/4 delayers-polarization-maintaining fiber coupler-polarization maintaining optical fibre-Y branch integrated optics phase-modulator.
(2) Y branch integrated optics phase-modulator-polarization maintaining optical fibre-polarization-maintaining fiber coupler-λ/4 delayers-sensor fibre-catoptron-sensor fibre-λ/4 delayers-polarization-maintaining fiber coupler-Bao off-delay optical fiber-Y branch integrated optics phase-modulator.
Owing to be connected with polarization maintaining optical fibre two-way optical fiber by protecting off-delay optical fiber between Y branch integrated optics phase-modulator and the polarization-maintaining fiber coupler, protect the length of the length of off-delay optical fiber much larger than polarization maintaining optical fibre, so guarantor's off-delay optical fiber has delayed-action to the transmission of light, and fix time delay.When light transmits according to above-mentioned two approach, owing to be the light that same light source sends, and the distance of process is identical, will inevitably interfere at the polarizer place of Y branch integrated optics phase-modulator by some light, by modulation, can obtain faraday's phase information at tested current lead place to this part interference light.
Result of interference enters Optical Receivers by fiber coupler and changes electrical information into, enter analog to digital converter then and realize the conversion of analog quantity to digital quantity, the output of analog to digital converter inserts digital demodulator, digital demodulator is respectively adopted a plurality of points to the front and back semiperiod of the interference ac signal that analog to digital converter obtains, add up respectively, subtract each other then, obtain demodulating information, the output Access Control modulators modulate Y branch integrated optics phase-modulator of digital demodulator, be used for the feedback signal phase modulation (PM), to provide the feedback phase shift to form the closed loop monitoring, the output demodulating information of digital demodulator carries out microprocessor and carries out follow-up signal processing, electric current transmitted value in the output lead simultaneously.As can be seen, the mutual inductor light path system has good reciprocity in the utility model, and result of interference has only been carried the phase information that Faraday magnetooptical effect produces.Finally, realize that through detector the signal expression after the opto-electronic conversion is
S
d=0.5K
P·L·I
O·(1+cosΦ
F)
K in the formula
PBe the photoelectric conversion factors of detector, L is an optical path loss, I
OBe the light source output intensity, Φ
F=4NVI is that (wherein, N is the sensor fibre number of turn, and V is sensor fibre Fil moral (Verdet) constant, and I is an electric current transmitted value in the lead in the Faraday effect phase shift.
λ/4 delayers will be converted to circularly polarized light from the linearly polarized light of polarization-maintaining fiber coupler, and promptly the linearly polarized light of the x axle linearly polarized light that is converted to right-circularly polarized light, Y-axis is converted to left circularly polarized light.Two circularly polarized light process sensor fibre coils arrive the catoptron of end face, and signal is by total reflection, and along the backpropagation of sensor fibre coil, left circularly polarized light becomes right-circularly polarized light, right-circularly polarized light becomes left circularly polarized light.λ/4 delayers are converted to linearly polarized light with the circularly polarized light of backpropagation, and promptly right-circularly polarized light is converted to x axis polarized light, left circularly polarized light is converted to y axis polarized light.Further, described sensor fibre end face adopts faraday's rotating mirror, make when light is reflected, the polarization surface half-twist, and then be coupled to and realized double modulation in the sensor fibre, sensitivity can be doubled, and offset the influence of circular birefringence effectively light path, especially can eliminate the birefringence of any reciprocity in the phase-modulator fully, system's antijamming capability is stronger.
The beneficial effects of the utility model are: the utility model has designed a kind of all-fiber current transformator, its outstanding advantage is can improve one times of phse sensitivity under the environment of identical outer signals excitation, and can effectively avoid the influence of phase-modulator polarization state random variation to interference system; Simultaneously, the simple optical fiber that can realize phase-modulated information extracts.When the light feedback method that adopts plated film etc. not change the reflected version of plane of polarization is connected fibre optic phase modulator when terminal, can effectively offset the influence of circular birefringence: when adopting faraday rotator mirror as the light feedback assembly to light path, can eliminate the birefringence of any reciprocity in the phase-modulator fully, system's antijamming capability is strong.Gou Zao all-fiber current transformator thus, under the situation that does not change fiber lengths, phse sensitivity can double, not only improved the extractability of weak physical signalling, and overcome temperature, vibration, the interference of various environmental factors such as electromagnetic interference (EMI), need not introduce power supply in the higher-pressure region, and the fiber end face of sensor fibre adopts catoptron to form the light feedback control loop as reflecting surface, sensitivity can be doubled, and offset the influence of circular birefringence effectively to light path, so system's antijamming capability is stronger, can be used for complexity, in the rugged environment.
Description of drawings
Fig. 1 is an all-fiber current transformator basic block diagram of the present utility model.
Fig. 2 is the inner structure synoptic diagram of Y branch integrated optics phase-modulator
1, light source
2, Optical Receivers
3, analog to digital converter
4, digital demodulator
5, microprocessor
6, modulating driver
7, Y branch integrated optics phase-modulator
8, fiber coupler
9, protect off-delay optical fiber
17, polarization maintaining optical fibre
10, polarization-maintaining fiber coupler
11, λ/4 delayers
12, sensor fibre
13, catoptron
14, the polarizer
15, phase-modulator
16 splitters
Embodiment
The utility model provides a kind of all-fiber current transformator, describes embodiment of the present utility model in detail below in conjunction with accompanying drawing.
A kind of all-fiber current transformator is made up of light source 1, Optical Receivers 2, analog to digital converter 3, digital demodulator 4, microprocessor 5, modulating driver 6, Y branch integrated optics phase-modulator 7, fiber coupler 8, guarantor's off-delay optical fiber 9, polarization maintaining optical fibre 17, polarization-maintaining fiber coupler 10, λ/4 delayers 11, sensor fibre 12 and catoptron 13.Its connected mode is: the first input end of the light output end input optical fibre coupling mechanism 8 of light source 1, second input end of Optical Receivers 2 and fiber coupler 8 links to each other, Optical Receivers 2, digital quantizer 3, digital demodulator 4, microprocessor 5 links to each other successively, digital demodulator 4 links to each other with Y branch integrated optics phase-modulator 7 by modulating driver 6, arbitrary output terminal of fiber coupler 8 links to each other with the input end of Y branch integrated optics phase-modulator 7, Y branch integrated optics phase-modulator 7 links to each other with polarization-maintaining fiber coupler 10 with polarization maintaining optical fibre 17 two-way optical fiber by protecting off-delay optical fiber 9, polarization-maintaining fiber coupler 10 links to each other with λ/4 delayers 11, the sensor fibre 12 that λ/4 delayers, 11 places pick out is wrapped on the tested current lead, and the end of sensor fibre 12 is installed a catoptron 13.
Y branch integrated optics phase-modulator is to be made up of 14, one splitters 16 of a polarizer and an optical phase modulator 15
The light of light source 1 enters Y branch integrated optics phase-modulator 7 through fiber coupler 8, the polarizer 14 in the Y branch integrated optics phase-modulator 7 carries out being divided into after the phase modulation (PM) linearly polarized light of x and two patterns of y with input optical signal, and by splitter two-way output in 16 fens; Phase-modulator 15 carries out synchronous modulation according to the modulation signal from digital demodulator 4 to the orthogonalized linearly polarized light of two-way, first output terminal of Y branch integrated optics phase-modulator 7 is through protecting the first input end of off-delay optical fiber 9 input polarization-maintaining fiber couplers 10 then, second output terminal of Y branch integrated optics phase-modulator 7 is through second input end of polarization maintaining optical fibre 17 input polarization-maintaining fiber couplers 10, and the arbitrary output terminal output x of polarization-maintaining fiber coupler 10 and the linearly polarized light of two patterns of y transfer to λ/4 delayers 11; At λ/4 delayers, 11 places, two bunch polarisations are converted into left-handed rotatory polarization and dextrorotation rotatory polarization respectively, advance people's sensor fibre 12; Two light beams run into catoptron 13 propagating when reaching home in the sensor fibre 12 of lead, light returns along same path.Electric current in the lead is because Faraday effect produces magnetic field, when the light in the optical fiber during around wire spread, because the effect in magnetic field makes that the transmission speed of dextrorotation rotatory polarization and left-handed rotatory polarization is different, differ thereby form, when two bundle rotatory polarizations are transferred to sensor fibre 12 ends, direct reflection takes place, two bundle rotatory polarizations are in the left-handed change dextrorotation of modes swap, dextrorotation becomes left-handed back and returns along original optical path, effect doubles, and the linearly polarized light patterns that change two bundle orthogonal modes at λ/4 delayers, 11 places once more into have also been exchanged.
In the course of the work, the distance of light in the described all-fiber current transformator of present embodiment is:
(1)7-9-10-11-12-13-12-11-10-17-7;
(2)7-17-10-11-12-13-12-11-10-9-7;
Owing to be connected with polarization maintaining optical fibre 17 two-way optical fiber by protecting off-delay optical fiber 9 between Y branch integrated optics phase-modulator 7 and the polarization-maintaining fiber coupler 10, protect the length of the length of off-delay optical fiber 9 much larger than polarization maintaining optical fibre 17, so protect the transmission of 9 pairs of light of off-delay optical fiber delayed-action is arranged, and fix time delay.When light transmits according to above-mentioned two approach, owing to be the light that same light source sends, and the distance of process is identical, will inevitably interfere at the polarizer 14 places of Y branch integrated optics phase-modulator 7 by some light, by modulation, can obtain faraday's phase information at tested current lead place to this part interference light.
Result of interference enters Optical Receivers 2 by fiber coupler 8 and changes electrical information into, enter analog to digital converter 3 then and realize the conversion of analog quantity to digital quantity, the output of analog to digital converter 3 inserts digital demodulator 4, digital demodulator 4 is respectively adopted a plurality of points to the front and back semiperiod of the interference ac signal that analog to digital converter 3 obtains, add up respectively, subtract each other then, obtain demodulating information, the output Access Control driver 6 modulation Y branch integrated optics phase-modulators 7 of digital demodulator 4, be used for the feedback signal phase modulation (PM), to provide the feedback phase shift to form the closed loop monitoring, the output demodulating information of digital demodulator 4 carries out microprocessor 5 and carries out follow-up signal processing, electric current transmitted value in the output lead simultaneously.As can be seen, the mutual inductor light path system has good reciprocity in the utility model, and result of interference has only been carried the phase information that Faraday magnetooptical effect produces.Finally, through the signal expression after the opto-electronic conversion be
S
d=0.5K
P·L·I
O·(1+cosΦ
F)
K in the formula
PThe photoelectric conversion factors that is, L are optical path loss, I
OBe the light source output intensity, Φ
F=4NVI is that (wherein, N is the sensor fibre number of turn, and V is sensor fibre Fil moral (Verdet) constant, and I is an electric current transmitted value in the lead in the Faraday effect phase shift.
Light source 1 can be any in following: operation wavelength is the semiconductor laser diode (LD) of 1310nm or 1550nm, semiconductor light-emitting-diode (LED) laser instrument, super-radiance light emitting diode (SLD) laser instruments etc., present embodiment selection work wavelength is the semiconductor laser diode of 1550nm.
In the utility model, fiber coupler 8 selects for use 2 * 2 fiber couplers, polarization-maintaining fiber coupler 10 to select 2 * 2 polarization-maintaining fiber couplers for use, they luminous power divide equally, promptly their luminous power splitting ratio is 1: I.
Fig. 2 is the structural representation of Y branch integrated optics phase-modulator 7, and this device comprises the polarizer 14, splitter 16 and phase-modulator 15.The described polarizer 14 is divided into the linearly polarized light signal of two quadratures with light signal, and transmits along the x axle and the Y-axis of optical fiber respectively.The luminous power of described splitter 16 is divided equally, and promptly its luminous power splitting ratio is 1: I.The birefringent characteristic that described optical phase modulator 15 utilizes optical fiber carries out synchronous modulation to the linearly polarized light of two quadratures, and modulation signal is from modulating driver 6.Behind the input light input Y branch integrated optics phase-modulator 7, the polarizer 14 of Y branch integrated optics phase-modulator 7 inside is converted into input optical signal the linearly polarized light of x and two patterns of y, the Y splitter is divided into two-way output with linearly polarized light, two-way output light enters optical phase modulator, one of its y branch waveguide is used for the offset signal modulation, another is used for the feedback signal phase modulation (PM), forms the closed loop monitoring so that the feedback phase shift to be provided.
Described Y branch integrated optics phase-modulator 7 comprises an input end and two output terminals, and the input end of described Y branch integrated optics phase-modulator receives input light; Two orthogonalized line polarisation mode light signals of output terminal beam split output two bundles of Y branch integrated optics phase-modulator.Y branch integrated optics phase-modulator 7 utilizes integrated optics technique, and several passive optical devices of constituting fibre optic interferometer minimum reciprocal structure are linked together with the form of integrated light guide, thereby has improved the reliability of system works.
Described light source 1, Optical Receivers 2,2 * 2 fiber couplers 8 adopt optical fiber to be connected with Y branch integrated optics phase-modulator 7.
Adopt polarization maintaining optical fibre to connect between described Y branch integrated optics phase-modulator 7,2 * 2 polarization-maintaining fiber couplers 10, λ/4 delayers 11, sensor fibre 12 and the catoptron 13, make single-mode optics keep single polarization state, thereby eliminate the influence of fiber birefringence variation properties of product.
The reciprocity structure that Fig. 1 represents is the ultimate principle structural drawing of all-fiber current transformator, can guarantee the equivalent optical path of all-fiber current transformator positive and negative two direction light waves under no magnetic field state fully.
Described sensor fibre coil 12 is ultra-low birefringence fiber or common low-birefringence single-mode fiber, twines some circles around the high-tension current bus.λ/4 delayers 11 will be converted to circularly polarized light from the linearly polarized light of 2 * 2 polarization-maintaining fiber couplers 10, and promptly the linearly polarized light of the x axle linearly polarized light that is converted to right-circularly polarized light, Y-axis is converted to left circularly polarized light.Two circularly polarized light process sensor fibre coils 12 arrive the catoptron 13 of end faces, and signal is by total reflection, and along 12 backpropagations of sensor fibre coil, left circularly polarized light becomes right-circularly polarized light, right-circularly polarized light becomes left circularly polarized light.λ/4 delayers 11 are converted to linearly polarized light with the circularly polarized light of backpropagation, and promptly right-circularly polarized light is converted to x axis polarized light, left circularly polarized light is converted to y axis polarized light.
Described sensor fibre end face adopts faraday's rotating mirror, make when light is reflected, the polarization surface half-twist, and then be coupled to and realized double modulation in the sensor fibre, sensitivity can be doubled, and offset the influence of circular birefringence effectively to light path, and especially can eliminate the birefringence of any reciprocity in the phase-modulator 15 fully, system's antijamming capability is stronger.
Here description of the present utility model and application are illustrative, are not to want with scope restriction of the present utility model in the above-described embodiments.Here the distortion of disclosed embodiment and change are possible, and the various parts of the replacement of embodiment and equivalence are known for those those of ordinary skill in the art.Those skilled in the art are noted that under the situation that does not break away from spirit of the present utility model or essential characteristic, and the utility model can be with other forms, structure, layout, ratio, and realize with other elements, material and parts.Under the situation that does not break away from the utility model scope and spirit, can carry out other distortion and change here to disclosed embodiment.