CN203606428U - Optical fiber current sensor - Google Patents
Optical fiber current sensor Download PDFInfo
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- CN203606428U CN203606428U CN201320825800.8U CN201320825800U CN203606428U CN 203606428 U CN203606428 U CN 203606428U CN 201320825800 U CN201320825800 U CN 201320825800U CN 203606428 U CN203606428 U CN 203606428U
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Abstract
The utility model discloses an optical fiber current sensor, and the current sensor comprises an optical path unit, which is connected through a polarization-maintaining optical fiber, and also comprises an FP cavity. A quarter-wave plate is disposed between the polarization-maintaining optical fiber and the FP cavity. The optical path unit comprises a broadband light source, an optical fiber coupler, an optical fiber polarizer, and an optical phase modulator, wherein the broadband light source, the optical fiber coupler, the optical fiber polarizer and the optical phase modulator are sequentially connected. The optical fiber coupler is connected with a modulating signal generator through a photoelectric detector. The FP cavity comprises a polarization-maintaining coupler, a first Faraday rotating mirror, a second Faraday rotating mirror, and a sensing fiber which is used for connecting a to-be-detected current wire. One end of the sensing fiber is connected with the first Faraday rotating mirror, and the other end of the sensing fiber is connected with one port at one side of the polarization-maintaining coupler. Two ports at the other side of the polarization-maintaining coupler are respectively connected with the second Faraday rotating mirror and the quarter-wave plate. The current sensor provided by the utility model can improve the precision of current measurement, especially the measurement of a small current, thereby providing a feasible method for the engineering of current measurement of the optical fiber current sensor.
Description
Technical field
The utility model belongs to fibre optic current sensor field, is specifically related to a kind of reflective Sagnac type fibre optic current sensor based on polarization interference and faraday's rotating mirror FP chamber.
Background technology
Electric current is the basic parameter of electric system, and current sensor is the important devices of measuring electric current.The aspects such as the electric current metering of induction current sensor in electric system all the time,, distributing electric power, relay protection, control enclosure supervision play a part very crucial.Along with the raising of relay protection, electrical equipment automaticity and power system insulation grade; there is the problems such as insulation, magnetic saturation and electromagnetic interference (EMI), little, the difficult transportation of dynamic range and installation in traditional current sensor based on electromagnetic induction, can not meet the needs of growing electric system due to it.For these problems, people have done many-sided effort, wherein the most competitive and application prospect give full play to the advantage of optical fiber sensing technology when number, to realize the detection of electric current and the effective fibre optic current sensor of protection whole system.Fibre optic current sensor (Fiber-optical Current Sensor) is because adopt optical fiber as sensor information, so have very large advantage at aspects such as insulativity, anti-electromagnetic interference (EMI), reliabilities than traditional electromagnetic type current sensor.And it is containing AC coil, do not exist open circuit dangerous, volume is little, lightweight, cost is low, easy for installation, therefore, as the regeneration product of traditional electrical magnetic-type current sensor, enjoys in recent years domestic and international researchist's attention.
In Configuration of Optical Fiber Current, reflective Sagnac type fibre optic current sensor, owing to having good reciprocal structure and stronger anti-external interference ability, is an all-fiber current sensor scheme with practical value.But because fibre optic current sensor is based on Faraday magnetooptical effect, in the time that little electric current is measured, because faraday's phase shift that electric current produces is less, affect the accuracy of current sensor, also limited its measurement range.For this kind of situation, if improve faraday's phase shift of its generation from light path, conventionally there are two kinds of methods.One is to increase the sensor fibre number of turn, so really, can increase faraday's phase shift, but when the sensor fibre number of turn increases, the linear birefrigence that sensor fibre is introduced and circular birefringence also increase thereupon, and the linear birefrigence of these introducings and circular birefringence meeting increase the error of whole sensor-based system.Although successively proposed " high circular birefringence optical fiber ", " spun optical fiber ", " twisted fiber ", " annealing optical fiber ", " low birefringent fiber " etc. in recent years, linear birefrigence is still a very important factor that affects the polarization error of fibre optic current sensor.The method of the another kind of faraday of raising phase shift is to adopt the larger sensor fibre of Verdet constant, and as CdSe doped fiber etc., this type optical fiber often cost is higher, also has certain distance from commercialization.Therefore, seeking a kind of method can increase faraday's phase shift that weak current produces, and the widespread use of fibre optic current sensor is had to very important meaning.
Publication number is that the Chinese utility model patent application of CN103197119A discloses a kind of interference-type optical fiber current sensor based on magneto-optic modulation, it comprises wideband light source, fiber coupler, optical fiber " circle " polarizer, " circle " polarization-maintaining fiber coupler, fiber magnetic optical modulator, " circle " protects inclined to one side transmission cable, sensing fiber ring, photodetector and signal processing unit, wherein wideband light source is by after fiber coupler, be connected with the input end of optical fiber " circle " polarizer, the output terminal of " circle " polarizer is connected with an input end of " circle " polarization-maintaining fiber coupler, one end that one output terminal of " circle " polarization-maintaining fiber coupler is protected inclined to one side transmission cable with " circle " is connected, and the other end that " circle " protects inclined to one side transmission cable is connected with sensing fiber ring, another output terminal of " circle " polarization-maintaining fiber coupler is connected with the input end of magneto-optic modulator, the output terminal of magneto-optic modulator is connected with sensing fiber ring, a modulation signal generator in signal processing unit is connected with magneto-optic modulator, detector is connected with a photoelectric conversion unit in signal processing unit, and light signal is become to electric signal output or is further processed.Although this fibre optic current sensor has and reduces modulating speed, need to not carry out the aligning of polarization principal axis and can greatly reduce the advantage such as technical difficulty of the active modulation scheme of interference-type optical fiber current sensor in when welding, but because its measuring accuracy is accurate not enough, anti-environmental interference ability is difficult to meet the demands, complex process, high in cost of production factor, be therefore unfavorable for carrying out the current measurement through engineering approaches of fibre optic current sensor.
Utility model content
In order to overcome the above-mentioned defect of prior art, the purpose of this utility model is to propose a kind of reflective Sagnac type fibre optic current sensor.
The utility model is achieved by the following technical solution:
A kind of fibre optic current sensor, comprise the optical path unit and the FP chamber that connect by polarization maintaining optical fibre, between described polarization maintaining optical fibre and FP chamber, be connected with quarter-wave plate, described optical path unit comprises the wideband light source connecting successively, fiber coupler, the optical fiber polarizer and optical phase modulator, described fiber coupler is also connected with modulation signal generator by photodetector, wherein: described FP chamber comprises polarization-maintaining coupler, the first faraday rotation mirror, the second faraday rotation mirror and for connecting the sensor fibre of current lead to be measured, one end of described sensor fibre is connected with the first faraday rotation mirror, the other end is connected with a port in polarization-maintaining coupler one side, two ports on described polarization-maintaining coupler opposite side are connected with the second faraday rotation mirror and quarter-wave plate respectively.
Further, the tail optical fiber main shaft of the described optical fiber polarizer and optical phase modulator enter the welding at 45 ° of fine main shaft, the tail optical fiber main shaft of described polarization maintaining optical fibre and quarter-wave plate enter the welding at 45 ° of fine main shaft.
Further, the type of described polarization-maintaining coupler is 1 × 2 polarization-maintaining coupler or 2 × 2 polarization-maintaining couplers.
Further, the type of described sensor fibre is low birefringent fiber or protects circular fiber.
Compared with prior art, the beneficial effects of the utility model are:
The utility model is by increasing by one by polarization-maintaining coupler, sensor fibre and two FP chambeies that faraday's rotating mirror forms, making to input light enters behind faraday's rotating mirror FP chamber, between two faraday's rotating mirrors, carry out multiple reflections, with faraday's phase shift that in increase system output light, electric current is introduced, under identical fiber lengths, can obtain the measuring accuracy that is several times as much as conventional interference type fibre optic current sensor, can realize better the measurement of the especially little electric current of electric current, thereby provide a kind of feasible method for the current measurement through engineering approaches of fibre optic current sensor.
In addition,, if obtain accuracy of detection same as the prior art, the utility model can shorten the length of sensor fibre greatly.The utility model is for providing accurately electrical signal data in earlier stage to the measurement of direct current or alternating current.
Accompanying drawing explanation
Fig. 1 is the structural representation of the utility model fibre optic current sensor embodiment;
Fig. 2 is the structural representation in faraday rotation mirror FP chamber in the utility model;
Fig. 3 is optical circulator operation schematic diagram;
Wherein, 1-wideband light source, 2-optical circulator, the 3-optical fiber polarizer, 4-optical phase modulator, 5-polarization maintaining optical fibre, 6-quarter-wave plate, 7-polarization-maintaining coupler, 8-sensor fibre, 9-the first faraday rotation mirror, 10-the second faraday rotation mirror, 11-photodetector, 12-modulation signal generator, 13-current lead to be measured.
Embodiment
Below in conjunction with accompanying drawing, reflective Sagnac type fibre optic current sensor of the present utility model is described in further detail.
As shown in Figure 1, this routine fibre optic current sensor comprises that the splitting ratio of selecting in wideband light source 1, optical circulator 2, the optical fiber polarizer 3, optical phase modulator 4, polarization maintaining optical fibre 5, quarter-wave plate 6, this example of polarization-maintaining coupler 7(is 10:90), sensor fibre 8, current lead to be measured 13, the first faraday rotation mirror 9, the second faraday rotation mirror 10, photodetector 11 and modulation signal generator 12.
Principle of work is: the light that wideband light source SLD1 sends becomes linearly polarized light after optical circulator 2 is transferred to the optical fiber polarizer 3, the tail optical fiber of the other end of the optical fiber polarizer 3 and optical phase modulator 4 carries out 45 degree weldings, and the linearly polarized light of input is divided into the orthogonal linearly polarized light of two bundles.Two bundle polarized lights spreads into respectively optical phase modulator 4, the modulation signal that optical phase modulator provides according to modulation signal generator carries out synchronous modulation to the orthogonal linearly polarized light of two bundles, after transmit through polarization maintaining optical fibre 5.Two bundles are carrying out, after the quarter-wave plate 6 of 45 degree weldings, becoming respectively left circularly polarized light and right-circularly polarized light through polarization maintaining optical fibre and with polarization maintaining optical fibre through the mutually orthogonal linearly polarized light of ovennodulation.This two bundles circularly polarized light goes out to inject sensor fibre 8 from port c and transmits after polarization-maintaining fiber coupler port b, carrying after the faraday phase shift that electric current causes, reflect through the first faraday rotation mirror 9, left circularly polarized light before becomes right-circularly polarized light, right-circularly polarized light before becomes left circularly polarized light, again enter polarization-maintaining fiber coupler port c through sensor fibre, after polarization-maintaining fiber coupler, 10% light is from polarization-maintaining fiber coupler port b outgoing, enter optical fiber quarter-wave plate, by polarization maintaining optical fibre, optical phase modulator, at the polarizer, place interferes, enter photodetector through optical circulator again, by photodetector, light signal is converted to electric signal output, remaining 90% light is from polarization-maintaining fiber coupler port a outgoing, reflect through the second faraday rotation mirror 10, the polarization state of two-beam changes again, left circularly polarized light becomes right-circularly polarized light, right-circularly polarized light becomes left circularly polarized light, after polarization-maintaining fiber coupler port a, again enter sensor fibre transmission, the light that enters sensor fibre from polarization-maintaining fiber coupler port b is again reflected back polarization-maintaining coupler 7 through the second faraday rotation mirror 10 at the light that always has 90% after the first faraday rotation mirror 9 reflections and enters sensor fibre 8.So the first faraday rotation mirror 9, the second faraday rotation mirror 10, polarization-maintaining fiber coupler 7 and sensor fibre 8 have formed faraday's rotating mirror FP chamber.The electric signal detecting at photodetector 11 places is all interference signal compositions that reflect the bundle of two after different cycles coherent light in faraday's rotating mirror FP chamber.Because the circularly polarized light in this example can carry out multiple reflections in FP chamber, therefore can realize the extraction of the electric signal to circulation specific times, thereby obtain current value to be measured more accurately.
To sum up, the utility model utilizes two faraday rotation mirrors and polarization-maintaining coupler and sensor fibre, forms faraday's rotating mirror FP chamber, as the fiber-optic current sensor unit of system.By adjusting when kind and the number of turn of sensor fibre of light splitting of polarization-maintaining coupler, can better realize the measurement of the especially little electric current of electric current.The utility model can, for the measurement to DC current, also can be applied to the measurement to alternating current.Therefore the utlity model has good actual application value.
The above-described example only polarization-maintaining coupler take splitting ratio as 10:90 describes as example, and there is no kind and the number of turn of specific sensor fibre.In fact, should, by improving the splitting ratio (as 1:99) of polarization-maintaining fiber coupler, select sensor fibre and the number of turn thereof of suitable type simultaneously, and can the especially little electric current of electric current be realized more accurately and being measured.Should be understood that; for those skilled in the art; in the disclosed content of the utility model; can also make some equivalent variations and replacement; such as adding one section of new sensor fibre or replace optical circulator etc. with fiber coupler between polarization-maintaining coupler and first faraday's rotating mirror, these equivalent variations and replace and also should be considered as protection domain of the present utility model.
Finally should be noted that: above embodiment is only in order to illustrate that the technical solution of the utility model is not intended to limit, although the utility model is had been described in detail with reference to above-described embodiment, those of ordinary skill in the field are to be understood that: still can modify or be equal to replacement embodiment of the present utility model, and do not depart from any modification of the utility model spirit and scope or be equal to replacement, it all should be encompassed in the middle of claim scope of the present utility model.
Claims (4)
1. a fibre optic current sensor, comprise the optical path unit and the FP chamber that connect by polarization maintaining optical fibre, between described polarization maintaining optical fibre and FP chamber, be connected with quarter-wave plate, described optical path unit comprises the wideband light source, fiber coupler, the optical fiber polarizer and the optical phase modulator that connect successively, described fiber coupler is also connected with modulation signal generator by photodetector, it is characterized in that:
Described FP chamber comprises polarization-maintaining coupler, the first faraday rotation mirror, the second faraday rotation mirror and for connecting the sensor fibre of current lead to be measured, one end of described sensor fibre is connected with the first faraday rotation mirror, the other end is connected with a port in polarization-maintaining coupler one side, and two ports on described polarization-maintaining coupler opposite side are connected with the second faraday rotation mirror and quarter-wave plate respectively.
2. fibre optic current sensor according to claim 1, it is characterized in that: the tail optical fiber main shaft of the described optical fiber polarizer and optical phase modulator enter the welding at 45 ° of fine main shaft, the tail optical fiber main shaft of described polarization maintaining optical fibre and quarter-wave plate enter the welding at 45 ° of fine main shaft.
3. fibre optic current sensor according to claim 1, is characterized in that: described polarization-maintaining coupler is selected 1 × 2 polarization-maintaining coupler or 2 × 2 polarization-maintaining couplers.
4. fibre optic current sensor according to claim 1, is characterized in that: described sensor fibre is selected low birefringent fiber or protected circular fiber.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320825800.8U CN203606428U (en) | 2013-12-13 | 2013-12-13 | Optical fiber current sensor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201320825800.8U CN203606428U (en) | 2013-12-13 | 2013-12-13 | Optical fiber current sensor |
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| CN203606428U true CN203606428U (en) | 2014-05-21 |
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| CN201320825800.8U Expired - Lifetime CN203606428U (en) | 2013-12-13 | 2013-12-13 | Optical fiber current sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104459267A (en) * | 2014-11-27 | 2015-03-25 | 哈尔滨理工大学 | Thin film type all-fiber current transformer with temperature compensation |
| CN110988435A (en) * | 2019-11-29 | 2020-04-10 | 中国人民解放军92942部队 | Optical path system for improving signal-to-noise ratio of optical fiber current sensor |
| CN111458553A (en) * | 2020-04-29 | 2020-07-28 | 中国矿业大学 | High-sensitivity all-fiber current measuring device and method with double-circulation structure |
-
2013
- 2013-12-13 CN CN201320825800.8U patent/CN203606428U/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104459267A (en) * | 2014-11-27 | 2015-03-25 | 哈尔滨理工大学 | Thin film type all-fiber current transformer with temperature compensation |
| CN104459267B (en) * | 2014-11-27 | 2017-05-24 | 哈尔滨理工大学 | Thin film type all-fiber current transformer with temperature compensation |
| CN110988435A (en) * | 2019-11-29 | 2020-04-10 | 中国人民解放军92942部队 | Optical path system for improving signal-to-noise ratio of optical fiber current sensor |
| CN111458553A (en) * | 2020-04-29 | 2020-07-28 | 中国矿业大学 | High-sensitivity all-fiber current measuring device and method with double-circulation structure |
| CN111458553B (en) * | 2020-04-29 | 2021-03-23 | 中国矿业大学 | High-sensitivity all-fiber current measuring device and method with double-circulation structure |
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Granted publication date: 20140521 |