Robust enhanced optical fiber current sensor and control method thereof

Abstract

According to the robust enhanced high-precision optical fiber current sensor and the control method thereof, the tube core of the light source is controlled to work at the set working temperature and under the driving current, the problems that the output light power of the light source is attenuated and the average wavelength is unstable can be solved, and constant power and constant wavelength control over the light source is ensured; the integrated wave plate device is controlled to work at the set target temperature, the temperature change of an existing lambda / 4 wave plate and errors caused by temperature-induced stress can be reduced, and therefore long-term stability of the phase delay angle of the wave plate and optimal adaptation of the phase delay angle of the wave plate and sensor system parameters are achieved. Aiming at the problem of light path average wavelength drift, a spectrum acquisition module is introduced, the light path average wavelength is monitored in real time, and secondary correction is carried out on wavelength related errors. Through the improvement of the three levels, the FOCS measurement precision long-term drift error can be suppressed.

Description

Technical Field

[0001] The present application relates to the technical field of optical fiber sensing measurement devices, and in particular to a robust enhanced high-precision optical fiber current sensor and a control method thereof. Background Art

[0002] Fiber Optical Current Sensor (FOCS) has the advantages of high measurement accuracy, wide frequency response range, large dynamic range, and good insulation performance. It has become a key equipment in the construction of smart substations.

[0003] FOCS can be divided into the optical path part and the detection circuit part. The optical path part consists of a light source, a fiber coupler / fiber circulator, a fiber polarizer, a phase modulator, a photodetector, a polarization-maintaining fiber delay ring, a polarization-maintaining transmission fiber, a λ / 4 wave plate, and a sensing fiber. The detection circuit part consists of a light source control circuit and a signal processing unit. Due to the use of a large number of semiconductor devices and optical fiber materials, the measurement accuracy of FOCS is affected by both internal and external factors during long-term use. The internal factors mainly include the attenuation of the light source output optical power, the drift of the optical path center wavelength, and the change of optical path loss. The external factors mainly include the change of the optical fiber refractive index distribution caused by external effects such as ambient temperature changes and vibration shocks, which in turn affects the performance of key components in the optical path. As a key optical component of FOCS, the λ / 4 wave plate will be affected by both the average wavelength drift and temperature changes during long-term operation. The long-term drift of the average wavelength will change the propagation constant of the wave plate fiber, causing its phase delay angle to change. This is the result of internal factors. The temperature change not only changes the propagation constant of the wave plate fiber, but also transfers part of the temperature-induced stress to the wave plate fiber through the wave plate packaging material, causing its phase delay angle to change. This is the result of the combined effects of internal and external factors.

[0004] In summary, the mechanism of the long-term drift of FOCS measurement accuracy is complex. The existing error compensation technology has not considered the measurement errors caused by the performance degradation of key optical components during long-term use, and it is difficult to meet the correction needs of additional errors caused by long-term use. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the existing FOCS measurement accuracy has long-term drift and low reliability, and thus provides a robust enhanced high-precision fiber optic current sensor and a control method thereof.

[0006] In a first aspect, the present invention provides a robust enhanced high-precision optical fiber current sensor, comprising:

[0007] An optical path module, comprising: a light source, a fiber coupler, a fiber polarizer, a spectrum collection module, a phase modulator, an integrated wave plate device and a photodetector connected in sequence; wherein the integrated wave plate device comprises a λ / 4 wave plate, a thermistor, a quartz substrate, a semiconductor refrigerator, a heat sink and a housing; light emitted by the light source enters the fiber coupler, one output end of the fiber coupler is connected to the fiber polarizer, the other output end of the fiber coupler is connected to the spectrum collection module, and the spectrum collection module collects spectrum information at the output end of the fiber coupler;

[0008] An optical fiber sensing ring, comprising an optical fiber sensing ring and a reflector, wherein one end of the optical fiber sensing ring is connected to the integrated wave plate device, and the reflector is arranged at the other end of the optical fiber sensing ring; the optical fiber sensing ring surrounds the outside of a current-carrying conductor, and the current-carrying conductor transmits a current to be measured;

[0009] The circuit module comprises a first control unit and a second control unit, wherein:

[0010] The first control unit is connected to the photodetector, receives the electrical signal output by the photodetector and analyzes it to obtain the current value of the current-carrying conductor and the optical power value received by the photodetector, wherein the optical power value is used to determine the modulation signal of the phase modulator;

[0011] The second control unit comprises:

[0012] A light source control circuit controls the core of the light source to operate at a set operating temperature and a driving current, so that the average wavelength of the light source is maintained at the set average wavelength, and the output optical power of the light source is constant at a preset power;

[0013] An integrated wave plate device control circuit determines the actual temperature of the integrated wave plate device according to the resistance value of the thermistor, and controls the operating temperature of the semiconductor refrigerator so that the integrated wave plate device operates at a target temperature;

[0014] A sensing optical fiber temperature acquisition circuit is used to obtain the temperature value of the sensing optical fiber;

[0015] The spectrum acquisition digital output signal conversion module receives the spectrum information acquired by the spectrum acquisition module and analyzes it to obtain spectrum data;

[0016] The second signal processing subunit obtains a corrected demodulated current value according to the current value of the current-carrying conductor, the temperature value of the sensing optical fiber, the spectral data and the optical power value, combined with a preset data correspondence list therein; the data correspondence is a correspondence between the current value of the current-carrying conductor, the temperature value of the sensing optical fiber, the optical power value and the demodulated current value obtained according to a calibration test.

[0017] The robust enhanced high-precision optical fiber current sensor described in some schemes further comprises a polarization-maintaining optical fiber delay ring:

[0018] The output fiber of the phase modulator is connected to the input fiber of the polarization-maintaining fiber delay ring at 0°, and the output fiber of the polarization-maintaining fiber delay ring is connected to the input fiber of the integrated wave plate device at 0°.

[0019] In some embodiments of the robust enhanced high-precision fiber optic current sensor, the output optical fiber of the fiber polarizer and the input optical fiber of the phase modulator are connected to each other by 45°.

[0020] In some embodiments of the robust enhanced high-precision fiber optic current sensor, the output optical fiber of the integrated wave plate device is connected to the sensing optical fiber using a 0° axis alignment.

[0021] The robust enhanced high-precision fiber optic current sensor described in some solutions also includes:

[0022] A temperature sensor is used to detect the temperature value of the sensing optical fiber and send it to the sensing optical fiber temperature acquisition circuit.

[0023] In some embodiments of the robust enhanced high-precision optical fiber current sensor, the first control unit further comprises:

[0024] A preamplifier circuit, whose input end receives the electrical signal output by the photodetector and amplifies it into a voltage signal;

[0025] A / D conversion circuit, converting the voltage signal into a digital signal;

[0026] A first signal processing subunit receives the digital signal and parses out the current value of the current-carrying conductor and the optical power value, and generates a digital value corresponding to the phase feedback signal; the first signal processing subunit outputs the current value of the current-carrying conductor;

[0027] The D / A conversion circuit receives the digital value corresponding to the phase feedback signal and converts it into an analog signal. The analog signal is applied to the phase modulator as a modulation signal.

[0028] In a second aspect, the technical solution of the present application provides a control method for a robust enhanced high-precision optical fiber current sensor as described in any technical solution of the first aspect, comprising:

[0029] Controlling the tube core temperature and driving current of the light source to ensure that the average wavelength of the light source is maintained at a set average wavelength and the output optical power of the light source is constant at a preset power;

[0030] Controlling the temperature of the integrated wave plate device to a target temperature, wherein the target temperature makes the measurement error of the integrated wave plate device at the temperature equal in magnitude and opposite in sign to the measurement error of the sensing optical fiber at the same temperature;

[0031] Error compensation correction is performed on the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber.

[0032] The control method of the robust enhanced high-precision fiber optic current sensor described in some schemes, wherein the core temperature and driving current of the light source are controlled to ensure that the average wavelength of the light source is maintained at a set average wavelength and the output optical power of the light source is constant at a preset power, comprises:

[0033] Establishing a light source control model, wherein the light source control model includes the corresponding relationship between the output optical power, average wavelength, and core temperature of the light source and the driving current;

[0034] According to the light source control model, by controlling the core temperature and driving current of the light source, the average wavelength output by the light source is kept constant at the set average wavelength, and the output optical power of the light source is kept constant at the preset power.

[0035] The control method of the robust enhanced high-precision optical fiber current sensor described in some schemes, wherein the core temperature and driving current of the light source are controlled to ensure that the average wavelength of the light source is maintained at a set average wavelength, and the output optical power of the light source is constant at a preset power, further comprising:

[0036] According to the spectrum data collected by the spectrum acquisition module, the measured wavelength of the light source is obtained;

[0037] Obtaining a difference between the measured wavelength and the set average wavelength;

[0038] In combination with the preset multidimensional parameter model and the difference, the core temperature and the driving current of the light source are adjusted so that the average wavelength output by the light source is constant at the set average wavelength, and the output optical power of the light source is constant at the preset power output optical power; wherein the multidimensional parameter model is used to record the output optical power of the light source, the average wavelength of the light source, and the corresponding relationship between the core temperature and the driving current.

[0039] The control method of the robust enhanced high-precision fiber optic current sensor described in some schemes, wherein the temperature of the integrated wave plate device is controlled at a target temperature, wherein the target temperature makes the measurement error of the integrated wave plate device equal in magnitude and opposite in sign to the measurement error of the sensing optical fiber, comprises:

[0040] Model the measurement error of the integrated wave plate device at different temperatures to obtain the measurement error model of the integrated wave plate device;

[0041] Modeling the measurement error of the sensing optical fiber at different temperatures to obtain the measurement error model of the sensing optical fiber at different temperatures;

[0042] According to the measured temperature of the sensing optical fiber, a corresponding sensing optical fiber error value is obtained based on the sensing optical fiber measurement error model;

[0043] Taking the inverse of the sensor optical fiber error value as the target error value of the integrated wave plate device;

[0044] The target temperature of the integrated wave plate device is obtained based on the target error value of the integrated wave plate device and the integrated wave plate measurement error model, and the operating temperature of the semiconductor refrigerator is controlled so that the operating temperature of the integrated wave plate device is the target temperature.

[0045] In some embodiments, the control method of the robust enhanced high-precision optical fiber current sensor, wherein the error compensation correction of the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber comprises:

[0046] Modeling the wavelength drift of the integrated wave plate device includes: changing the average wavelength of the light source input into the integrated wave plate device at different constant temperatures, and testing the measurement error caused by the different average wavelengths of the light sources; or changing the average wavelength of the light source input into the integrated wave plate device at different constant temperatures, and testing the phase delay angle change of the integrated wave plate device caused by the different average wavelengths of the light sources, and determining the measurement error according to the phase delay angle change; modeling according to the measurement results to obtain a wavelength drift error model of the integrated wave plate device at different constant temperatures;

[0047] According to the spectrum data collected by the spectrum collection module, the measured average wavelength of the light source is obtained;

[0048] Obtaining an error compensation coefficient of the integrated wave plate device according to a wavelength drift error model of the integrated wave plate device corresponding to the target temperature and in combination with the measured average wavelength of the light source;

[0049] The error compensation coefficient of the integrated wave plate device is sent to the second control unit for the second signal processing subunit to correct the demodulated current value.

[0050] In some embodiments, the control method of the robust enhanced high-precision fiber optic current sensor, wherein the error compensation correction of the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber further comprises:

[0051] Get the corresponding relationship between the average wavelength of the light source, the fiber Verdet constant and the measurement error: Where V is the fiber Verdet constant, λ c is the average wavelength of the light source, is the phase difference, ε is the measurement error;

[0052] Obtaining the wavelength drift of the sensing optical fiber according to the corresponding relationship and the measured wavelength of the light source;

[0053] An error compensation coefficient of the sensitivity of the sensing fiber is obtained according to the wavelength drift of the sensing fiber; the error compensation coefficient of the sensitivity of the sensing fiber is sent to the second control unit for the second signal processing subunit to correct the demodulated current value.

[0054] In a third aspect, the technical solution of the present application provides a packaging process for an integrated wave plate device in a robust enhanced high-precision optical fiber current sensor according to any technical solution of the first aspect, comprising:

[0055] Grooving a quartz substrate;

[0056] Placing the λ / 4 wave plate and the optical fibers at both ends thereof in the grooves opened on the quartz substrate and fixing them;

[0057] The quartz substrate is disposed on a heat sink, a thermistor is disposed on at least one side of the quartz substrate, and the size of the heat sink is larger than the size of the quartz substrate;

[0058] The heat sink is arranged on a semiconductor refrigerator, the size of the semiconductor refrigerator is greater than or equal to the size of the heat sink;

[0059] The semiconductor refrigerator is arranged in a shell, and the optical fibers at both ends are respectively led out from the fiber outlet holes at both ends of the shell and fixed;

[0060] Put the upper cover of the shell on and seal it with welding or sealant.

[0061] The packaging process of the integrated wave plate device in the robust enhanced high-precision fiber optic current sensor described in some schemes, wherein the λ / 4 wave plate and the optical fibers at both ends are placed in the grooves opened on the quartz and fixed: the λ / 4 wave plate and the optical fibers at both ends are fixed in a point-by-point manner using UV glue;

[0062] The semiconductor refrigerator is arranged in a shell, and the optical fibers at the two ends are respectively led out from the fiber outlet holes at the two ends of the shell and fixed: silicone rubber is used to fix the optical fibers at the fiber outlet holes at the two ends of the shell.

[0063] The above technical solution provided by the present invention has the following technical effects:

[0064] The robust enhanced high-precision fiber optic current sensor and its control method provided by the present invention can control the light source to work at a set working temperature and driving current, which can solve the problems of light output power attenuation and wavelength instability of the light source, and ensure constant power and constant wavelength control of the light source; the integrated wave plate device is controlled to work at a set target temperature, which can reduce the errors caused by temperature changes and temperature-induced stress of the existing λ / 4 wave plate, so as to achieve long-term stability of the wave plate phase delay angle and optimal adaptation of the wave plate phase delay angle to the sensor system parameters. In view of the problem of average wavelength drift of the optical path, a spectrum acquisition module is introduced to monitor the average wavelength of the optical path in real time, and a secondary correction is made to the wavelength-related errors. Through the above three levels of improvement, the present application scheme can suppress the output light power measurement error of the long-term drift error of the FOCS measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a schematic diagram of the structure of a robust enhanced high-precision optical fiber current sensor according to an embodiment of the present invention;

[0066] Figure 2 A schematic diagram of the circuit layout of the first control unit and the second control unit according to an embodiment of the present invention;

[0067] Figure 3 This is a flow chart of a control method of a robust enhanced high-precision optical fiber current sensor according to an embodiment of the present invention;

[0068] Figure 4 It is a schematic diagram of the processing steps of the integrated wave plate device according to the embodiment of the present invention;

[0069] Figure 5 It is a schematic diagram of the internal structure of the integrated wave plate device according to an embodiment of the present invention;

[0070] Figure 6 It is a perspective view of the packaging structure of the integrated wave plate device described in an embodiment of the present invention. DETAILED DESCRIPTION

[0071] The specific implementation of the present application is further described below with reference to the accompanying drawings.

[0072] It is easy to understand that according to the technical solution of the present application, without changing the essential spirit of the present application, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the entirety of the present application or as a limitation or restriction on the technical solution of the application.

[0073] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to different positions and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0074] This embodiment provides a robust enhanced high-precision fiber optic current sensor, such as Figure 1 and Figure 2 As shown, it includes an optical path module, an optical fiber sensor ring, and a circuit module, wherein:

[0075] The optical path module includes: a light source 1, a fiber coupler 2, a fiber polarizer 31, a spectrum acquisition module 13, a phase modulator 32, an integrated wave plate device 6, and a photodetector 9, which are connected in sequence; wherein the integrated wave plate device 6 includes a thermistor, a temperature maintenance component, and a λ / 4 wave plate, and the λ / 4 wave plate can be a fiber wave plate or a crystal wave plate; the temperature maintenance component includes a semiconductor refrigerator and a heat sink, the semiconductor refrigerator can work at a certain temperature, and the heat sink is a high thermal conductivity material. The light emitted by the light source 1 enters the fiber coupler 2, one output end of the fiber coupler 2 is connected to the fiber polarizer 31, and the other output end of the fiber coupler 2 is connected to the spectrum acquisition module 13, and the spectrum acquisition module 13 collects the spectrum information of the output end of the fiber coupler 2.

[0076] The optical fiber sensing ring includes a sensing optical fiber 7 and a reflector 8. One end of the sensing optical fiber is connected to the integrated wave plate device 6, and the reflector 8 is arranged at the other end of the sensing optical fiber 7. The sensing optical fiber 7 surrounds the outside of the current-carrying conductor 10, and the current-carrying conductor 10 transmits the current to be measured.

[0077] Combination Figure 2 As shown, the circuit module includes a first control unit 14 and a second control unit 12, wherein:

[0078] The first control unit 14 is connected to the photodetector 9 , receives the electrical signal output by the photodetector 9 and analyzes it to obtain the current value of the current-carrying conductor and the light power value received by the photodetector. The current value of the current-carrying conductor is used to determine the modulation signal of the phase modulator 32 .

[0079] The second control unit 12 includes:

[0080] The light source control circuit controls the core of the light source 1 to operate at a set operating temperature and driving current; keeps the average wavelength of the light source at the set average wavelength, and the output optical power of the light source is constant at a preset power.

[0081] The integrated wave plate device control circuit determines the actual temperature of the integrated wave plate device 6 according to the resistance value of the thermistor, and controls the working temperature of the semiconductor refrigerator to make the integrated wave plate device 6 work at the target temperature.

[0082] The sensing optical fiber temperature acquisition circuit obtains the temperature value of the sensing optical fiber 7.

[0083] The spectrum acquisition digital output signal conversion module receives the spectrum information acquired by the spectrum acquisition module 13 and analyzes it to obtain spectrum data.

[0084] The second signal processing subunit 12 obtains a corrected demodulated current value based on the current value of the current-carrying conductor, the temperature value of the sensing optical fiber, the spectral data and the optical power value, combined with a preset data correspondence list therein; the data correspondence is a correspondence between the current value of the current-carrying conductor, the temperature value of the sensing optical fiber, the optical power value and the demodulated current value obtained according to the calibration test.

[0085] In the scheme of the above embodiment, the optical fiber coupler 2 can select a 2×2 coupler. The integrated wave plate device 6 includes an input end pigtail and an output end pigtail, wherein the optical fiber type of the input end pigtail is a linear polarization maintaining optical fiber, and the optical fiber type of the output end pigtail is a circular polarization maintaining optical fiber, a single-mode optical fiber, a low birefringence optical fiber or a photonic crystal optical fiber. The types of the sensing optical fiber are: circular polarization maintaining optical fiber, single-mode optical fiber, low birefringence optical fiber, and photonic crystal optical fiber. The types of the reflector 8 can be: a coated optical fiber reflector, a metal patch optical fiber reflector, and a Faraday optical rotation reflector.

[0086] The robust enhanced high-precision fiber optic current sensor in the above scheme can solve the problems of output optical power attenuation and wavelength instability of the light source by controlling the core of the light source 1 to work at the set operating temperature and driving current, and ensure constant power and constant wavelength control of the light source 1; by controlling the integrated wave plate device 6 to work at the set target temperature, the error caused by temperature change and temperature-induced stress of the existing λ / 4 wave plate can be reduced to achieve long-term stability of the wave plate phase delay angle and optimal adaptation of the wave plate phase delay angle to the sensor system parameters. In view of the drift problem of the average wavelength in the optical path, the spectrum acquisition module 13 is introduced to monitor the average wavelength of the optical path in real time, and the wavelength-related error is corrected twice. The above scheme can suppress the error of long-term drift of FOCS measurement accuracy.

[0087] Further, as shown in the figure, the above-mentioned robust enhanced high-precision optical fiber current sensor also includes a polarization-maintaining optical fiber delay ring 4, which is connected to the phase modulator 32 and the integrated wave plate device 6 through a polarization-maintaining transmission optical fiber 5. Specifically, the output end optical fiber of the phase modulator 32 and the input end optical fiber of the polarization-maintaining optical fiber delay ring 4 are connected by 0° axis alignment, and the output end optical fiber of the polarization-maintaining optical fiber delay ring 4 and the input end optical fiber of the integrated wave plate device 6 are connected by 0° axis alignment. By setting the polarization-maintaining optical fiber delay ring 4, the polarization state of light can be effectively maintained.

[0088] Preferably, in a specific implementation, the output fiber of the fiber polarizer 31 is connected to the input fiber of the phase modulator 32 at 45°. The output fiber of the integrated wave plate device 6 is connected to the sensing fiber 7 at 0°.

[0089] In the above scheme, the temperature value of the sensing optical fiber 7 can be detected by the temperature sensor 11. Specifically, the temperature sensor 11 is used to detect the temperature value of the sensing optical fiber 7 and send it to the sensing optical fiber temperature acquisition circuit, thereby realizing real-time and accurate detection of the sensing optical fiber temperature value.

[0090] In the present application, the first control unit 14 further includes:

[0091] The preamplifier circuit receives the electrical signal output by the photodetector 9 at its input end and amplifies it into a voltage signal; the A / D conversion circuit converts the voltage signal into a digital signal; the first signal processing subunit receives the digital signal and parses out the current value of the current-carrying conductor and the optical power value, and generates a digital value corresponding to the phase feedback signal; the first signal processing subunit outputs the current value of the current-carrying conductor; the D / A conversion circuit receives the digital value corresponding to the phase feedback signal and converts it into an analog signal, and the analog signal is applied to the phase modulator 32 as a modulation signal. As shown in the figure, there is a connection relationship between the first control unit 14 and the second control unit 12, so the first control unit 14 can send the current value of the current-carrying conductor and the optical power value to the second control unit 12. The second control unit 12 uses the spectrum data transmitted by the spectrum acquisition digital output signal conversion module, the current value of the current-carrying conductor and the optical power value transmitted by the first signal processing subunit, and the temperature data transmitted by the temperature sensor 11 to calculate the corrected demodulated current value and output it through the output data line 15.

[0092] The above-mentioned scheme of the present application is based on the cooperation of the spectrum acquisition module, the spectrum acquisition digital output signal conversion module, the light source control circuit, the integrated wave plate device control circuit, and the sensor optical fiber temperature acquisition circuit, and corrects the wavelength drift error of the light source and the integrated wave plate device to suppress the error caused by the long-term drift of the FOCS measurement accuracy.

[0093] The embodiment of the present invention also provides a control method for the robust enhanced high-precision optical fiber current sensor described in any of the above solutions, such as Figure 3 As shown, the following steps are included:

[0094] S10: Controlling the tube core temperature and driving current of the light source to ensure that the average wavelength of the light source is maintained at a set average wavelength and the output optical power of the light source is constant at a preset power.

[0095] S20: Controlling the temperature of the integrated wave plate device to a target temperature, wherein the target temperature makes the measurement error of the integrated wave plate device at the temperature equal in magnitude and opposite in sign to the measurement error of the sensing optical fiber at the same temperature.

[0096] S30: performing error compensation correction on the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber.

[0097] The present invention proposes the above control method, which controls the light source at constant power and wavelength to address the problem of light source output optical power attenuation; controls the temperature of the integrated wave plate device to be constant to address the temperature change and temperature-induced stress error of the λ / 4 wave plate, so as to achieve long-term stability of the wave plate phase delay angle and optimal adaptation of the wave plate phase delay angle to the sensor system parameters. In response to the problem of average wavelength drift of the optical path, a spectrum acquisition module is introduced to monitor the average wavelength of the optical path in real time, and a secondary correction is made to the wavelength-related error, wherein the wavelength-related error also includes the additional error caused by the short-term measurement error with the wavelength drift.

[0098] Specifically, the control of the tube core temperature and the driving current of the light source in step S10 to ensure that the average wavelength of the light source is maintained at the set average wavelength and the output optical power of the light source is constant at the preset power can be achieved in the following two ways:

[0099] Method 1: Direct control of the light source output wavelength

[0100] S101: Establishing a light source control model, wherein the light source control model includes the output optical power, average wavelength, and the corresponding relationship between the tube core temperature and the driving current of the light source.

[0101] The main reason for the change of the average wavelength in the optical path is the change of the average wavelength of the light source. The average wavelength of the light source λ c Mainly affected by the core temperature T of the light source SLD and drive current ISLD Therefore, the average wavelength λ of the light source c It can be written as the core temperature T SLD and drive current I SLD The calculation model is:

[0102] λ c =f(T SLD ,I SLD )(1)

[0103] At the same time, the output optical power P of the light source SLD Also affected by the die temperature T SLD and drive current I SLD Therefore, the output optical power P of the light source SLD It can be written as the core temperature T SLD and drive current I SLD The calculation model is:

[0104] P SLD =g(T SLD ,I SLD )(2)

[0105] S102: According to the light source control model, by controlling the core temperature T of the light source SLD and drive current I SLD , so that the average wavelength λ of the light source output c At the set average wavelength, the output optical power P of the light source is constant. SLD The optical power is outputted at a constant preset power.

[0106] Based on the calculation model (1) of the wavelength of the light source and the calculation model (2) of the output optical power of the light source, the average wavelength λ of the light source is obtained through matching calculation. c Increase the light source output power P under the premise of unchanged SLD The required die temperature T SLD and drive current I SLD , and perform constant temperature and constant driving current control to achieve constant wavelength control under the premise of improving the output optical power of the light source.

[0107] As mentioned above, different light source chips have different light emission mechanisms, so the measured light source output optical power, light source average wavelength and corresponding light source die temperature T can be used to determine the light source output power. SLD and drive current I SLD , a mathematical model is established to achieve constant power and constant wavelength control. The specific modeling method is as follows:

[0108] When the driving current of the light source is constant, the core temperature T of the light source is adjusted SLD , the light source output power and the average wavelength of the light source and the core temperature T are measuredSLD The value of the die temperature T SLD and output optical power P SLD and the average wavelength λ of the light source c The array of "temperature-power-average wavelength" multi-dimensional parameter model of the light source is obtained. That is, when the driving current I SLD When constant, the test results in the following array:

[0109]

[0110] T SLD1n is the core temperature of the light source, n=1,2,3,4……n; P 1m is the light source output power, m = 1, 2, 3, 4 ... m, λ 1s is the average wavelength of the light source, s=1,2,3,4…s.

[0111] When the core temperature of the light source T SLD When constant, adjust the driving current I of the light source SLD , the measured light source output power P SLD and the average wavelength λ of the light source c With the driving current I SLD The value of the drive current I SLD The light source output power P SLD and the average wavelength λ of the light source c The array of "driving current-power-average wavelength" multi-dimensional parameter model of the light source is obtained. That is, when the core temperature T SLD When constant, the test results in the following array:

[0112]

[0113] I sld2j is the core temperature of the light source, j = 1, 2, 3, 4...j; P 2i is the light source output power, i=1,2,3,4...i,λ 2k is the average wavelength of the light source, k=1,2,3,4…k.

[0114] Fit the core temperature T of the light source SLD , the driving current of the light source I SLD The light source output power P SLD and the average wavelength λ of the light source c The relationship model is used as the light source control model. Based on the light source control model, the average wavelength of the light source can be kept horizontally at the set average wavelength.

[0115] Method 2: Feedback control of the average wavelength of the optical path based on the spectrum acquisition module

[0116] In this solution, a spectrum acquisition module is used to monitor and feedback the average wavelength of the light source in real time, and a photoelectric detector is used to monitor and feedback the output optical power of the optical path in real time. The method of controlling the average wavelength of the light source includes:

[0117] S111: Obtaining the actual measured wavelength of the light source according to the spectrum data collected by the spectrum collection module.

[0118] S112: Obtaining the difference between the measured wavelength and the preset wavelength.

[0119] S113: Adjust the core temperature T of the light source in combination with the preset multi-dimensional parameter model adjustment and the difference SLD and drive current I SLD , so that the average wavelength of the light source is c Constant at the set average wavelength, the output optical power P of the light source SLD Constant at a preset power; wherein the multidimensional parameter model is used to record the output optical power of the light source, the average wavelength of the light source, and the corresponding relationship between the core temperature and the driving current. The multidimensional parameter model can adopt the "temperature-power-wavelength" multidimensional parameter model obtained in method 1, based on the difference obtained in S112 and the above model, the average wavelength λ of the light source is c Perform feedback regulation to adjust the core temperature T of the light source SLD and the driving current I of the light source SLD , so that the measured average wavelength of the light source is consistent with the set average wavelength. At this time, a certain deviation in the output optical power of the light source is allowed.

[0120] Further preferably, in step S20, controlling the temperature of the integrated wave plate device to be at a target temperature, wherein the target temperature makes the measurement error of the integrated wave plate device at the temperature equal in magnitude and opposite in sign to the measurement error of the sensing optical fiber at the same temperature, comprises:

[0121] S201: Modeling the measurement error of the integrated wave plate device at different temperatures to obtain a measurement error model of the integrated wave plate device.

[0122] The measurement error (i.e., ratio error) of FOCS can be expressed as the ambient temperature T, the average wavelength of the light source λ c and the wave plate phase delay angle δ, which can be expressed as the ambient temperature T, the average wavelength of the light source λ c and stress σ, as shown in equations (5) and (6):

[0123] ε=f(T,λ c ,δ)(5)

[0124] δ=f 1 (T,λ c ,σ)(6)

[0125] Where T is the ambient temperature, λ c is the average wavelength of the light source, σ is the external stress on the wave plate, δ is the phase delay angle of the wave plate, and ε is the measurement error of FOCS. Therefore, changes in the internal physical parameters of the integrated wave plate device (such as temperature, wavelength, and stress) will directly lead to the measurement error of FOCS. In this application, the influence of external stress on the λ / 4 wave plate can be isolated through the internal packaging process of the integrated wave plate device, so the influence of stress on the λ / 4 wave plate in the above formula can be basically ignored. At the same time, the Verdet constant of the sensing fiber will also be affected by temperature changes, resulting in measurement errors of FOCS. The Verdet constant is related to the material of the sensing fiber and the frequency of light. In practical applications, since the material of the sensing fiber changes with temperature, the Verdet constant is also related to temperature. The typical temperature characteristics of the sensing fiber are expressed as:

[0126]

[0127] Among them, V 0 is the Verdet constant at room temperature, V is the Verdet constant, and T is the ambient temperature.

[0128] According to the above formula, V 0 The temperature characteristic of the measurement error of FOCS has a significant impact. Therefore, in this scheme, the measurement error of the integrated wave plate device is used to self-compensate the measurement error of the Verdet constant of the sensing fiber in FOCS.

[0129] S202: Modeling the measurement errors of the sensing optical fiber at different temperatures to obtain a measurement error model of the sensing optical fiber at different temperatures.

[0130] In specific implementation, the error measurement of the sensing optical fiber at different temperatures can be carried out in advance by means of calibration test, and a model is built after a series of values ​​are obtained. The model is used to record the corresponding relationship between the measurement error and the temperature of the sensing optical fiber.

[0131] S203: According to the actually measured temperature of the sensing optical fiber, a corresponding sensing optical fiber error value is obtained based on the sensing optical fiber measurement error model.

[0132] Substituting the measured sensing fiber temperature into the sensing fiber measurement error model, the FOCS measurement error caused by the measured sensing fiber temperature can be obtained.

[0133] S204: Taking the inverse of the error value of the sensing optical fiber as the target error value of the integrated wave plate device.

[0134] S205: Obtaining a target temperature of the integrated wave plate device based on the target error value of the integrated wave plate device and the integrated wave plate measurement error model, and controlling the operating temperature of the semiconductor refrigerator so that the operating temperature of the integrated wave plate device is the target temperature.

[0135] In this way, the target error value of the integrated wave plate device and the error value of the sensing optical fiber can cancel each other out, thereby performing point-to-point compensation for the sensing optical fiber measurement error and improving the measurement accuracy of the current sensor.

[0136] The above scheme of this embodiment models the measurement error of the integrated wave plate device and the measurement error of the sensing optical fiber respectively, obtains the sensing optical fiber error value at this time based on the measurement error model of the sensing optical fiber according to the measured sensing optical fiber temperature, takes the inverse of the sensing optical fiber error value to obtain the target error value of the integrated wave plate device, obtains the target temperature value based on the target error value of the integrated wave plate device and the measurement error model of the integrated wave plate device, and adjusts the control parameters of the semiconductor cooler in the integrated wave plate device so that the operating temperature of the integrated wave plate device is the target temperature value to compensate for the measurement error of the sensing optical fiber.

[0137] In actual applications, the requirements for measurement accuracy vary depending on the usage scenario of the fiber optic current sensor. When the fiber optic current sensor requires higher precision at room temperature, the phase delay angle of the integrated wave plate device can be made to be 90°. However, due to the measurement errors of the manufacturing process and the measuring tool, the phase delay angle of the integrated wave plate device actually manufactured has a certain deviation. This deviation is random and cannot be designed. At this time, the phase delay angle of the integrated wave plate device can be adjusted to 90° by adjusting the operating temperature of the integrated wave plate device. Therefore, if the initial phase delay angle of the integrated wave plate device is inaccurate due to the measurement errors of the manufacturing process and the measuring tool, the integrated wave plate device does not need to be remade, and the phase delay angle can be adjusted by adjusting the preset temperature.

[0138] The model of the phase delay angle of the integrated wave plate device is shown in the above formula (6). The sensitivity of the sensing fiber has a functional relationship with the ambient temperature and the average wavelength of the light source as shown in formula (8):

[0139] S=(T,λ c )(8)

[0140] Among them, S is the sensitivity of the sensing fiber, T is the ambient temperature, and λ c is the average wavelength of the optical path.

[0141] With the long-term operation of FOCS, the average wavelength of its light source cannot be kept constant. Therefore, after achieving constant wavelength control of the light source and constant temperature control of the integrated wave plate device, it is still necessary to perform secondary compensation for the wavelength drift error. The compensation methods include:

[0142] S301: Modeling the wavelength drift of the integrated wave plate device, including: changing the average wavelength of the light source input into the integrated wave plate device at different constant temperatures, and testing the measurement error caused by the different average wavelengths of the light source; or, changing the average wavelength of the light source input into the integrated wave plate device at different constant temperatures, and testing the change in the phase delay angle of the integrated wave plate device caused by the different average wavelengths of the light source, and determining the measurement error according to the change in the phase delay angle; and modeling the wavelength drift error model of the integrated wave plate device at different constant temperatures according to the measurement results.

[0143] S302: Obtaining the measured average wavelength of the light source according to the spectrum data collected by the spectrum collection module;

[0144] S303: Obtaining an error compensation coefficient of the integrated wave plate device according to a wavelength drift error model of the integrated wave plate device corresponding to the target temperature and in combination with the measured average wavelength of the light source;

[0145] S304: The error compensation coefficient of the integrated wave plate device is sent to the second control unit for the second signal processing subunit to correct the demodulated current value.

[0146] The integrated wave plate measurement error calculation model shown in the above formula (6) is used to model the measured data to obtain the wavelength drift error model of the integrated wave plate device. The wavelength drift is calculated based on the average wavelength of the measured light source collected by the spectrum acquisition module. According to the wavelength drift error model of the integrated wave plate device, the error compensation coefficient of FOCS is calculated, and the measured output value of FOCS is corrected twice.

[0147] S305: The corresponding relationship between the average wavelength of the light source, the fiber Verdet constant and the measurement error is: Where V is the fiber Verdet constant, λ c is the average wavelength of the light source, is the phase difference, ε is the FOCS measurement error;

[0148] S306: Obtaining a wavelength drift of the sensing optical fiber according to the corresponding relationship and the measured wavelength of the light source;

[0149] S307: Obtaining an error compensation coefficient of the sensitivity of the sensing optical fiber according to the wavelength drift of the sensing optical fiber

[0150] S308: The error compensation coefficient of the sensing optical fiber sensitivity is sent to the second control unit for the second signal processing subunit to correct the demodulated current value.

[0151] The error compensation coefficient of the integrated wave plate device and the error compensation coefficient of the sensing fiber sensitivity are combined to perform secondary compensation on the FOCS measurement error, thereby further improving the measurement accuracy of FOCS.

[0152] In some embodiments of the present application, a packaging process for the integrated wave plate device in the above-mentioned robust enhanced high-precision optical fiber current sensor is also provided, combined with Figure 4 and Figure 5 As shown, including:

[0153] S100: Grooving on a quartz substrate.

[0154] In specific implementation, the λ / 4 wave plate in the integrated wave plate device can be a fiber wave plate or a crystal wave plate, and the size of the quartz substrate 601 and the size of the slot can be selected according to the type of the λ / 4 wave plate and other actual needs. For example, when the λ / 4 wave plate is a fiber wave plate, the width of the quartz substrate 601 is 5 mm, the length is 50 mm, the thickness is 1 mm, and the diameter of the slot is 300 μm. When the λ / 4 wave plate is a crystal wave plate, the size of the quartz substrate 601 and the size of the slot can be determined according to the size of the crystal wave plate and the input and output collimators.

[0155] S200: Place the λ / 4 wave plate 602 and the optical fibers at both ends in the grooves opened on the quartz substrate 601 and fix them. The optical fibers at both ends include an input optical fiber 607 and an output optical fiber 608. The input optical fiber 607 is a linear polarization-maintaining optical fiber, and the output optical fiber 608 is a circular polarization-maintaining optical fiber. The λ / 4 wave plate 602 can be made in advance using a high-precision fusion splicing machine and a high-precision length measurement tool.

[0156] Preferably, the λ / 4 wave plate 602 and the optical fibers at both ends are fixed with low-stress UV glue, and the UV glue is fixed at points to reduce the influence of tension, torsional force or temperature stress on the λ / 4 wave plate 602 during use of the pigtail.

[0157] S300: placing the quartz substrate 601 on the heat sink 604, and placing a thermistor 605 on at least one side of the quartz substrate 601, wherein the size of the heat sink is larger than the size of the substrate.

[0158] The thermistor 605 is connected to the resistor pin 6052 via the resistor lead 6051. The heat sink 604 is welded or bonded to the substrate 601 and the thermistor 605 using a high thermal conductivity material.

[0159] S400: The heat sink 604 is placed on the semiconductor refrigerator 603, and the size of the semiconductor refrigerator is greater than or equal to the size of the heat sink. The semiconductor refrigerator 603 is connected via a refrigerator lead 6031 and a refrigerator pin 6032, and the lead and pin include a positive electrode and a negative electrode.

[0160] The semiconductor cooler 603 and the heat sink 604 are fixed by welding or bonding using a high thermal conductivity material.

[0161] S500: The semiconductor cooler 603 is disposed in the housing 606, and the optical fibers at both ends are led out from the fiber outlet holes at both ends of the housing and fixed.

[0162] The semiconductor refrigerator 603 is fixed to the housing 606 using a high thermal conductivity material. The optical fiber is fixed to the fiber outlet holes at both ends of the housing using low-stress silicone rubber.

[0163] S600: Cover the upper cover of the shell and seal it with welding or sealant.

[0164] The integrated wave plate device obtained by the above process in this application is as follows Figure 5 and 6 As shown, the integrated wave plate device includes an input end collimator 6071, an output end collimator 6081, a λ / 4 wave plate 602, a semiconductor refrigerator 603, a refrigerator lead 6031, a refrigerator pin 6032, a heat sink 604, a thermistor 605, a resistor lead 6051, a resistor pin 6052, a housing 606, and a fixing bracket 609. The input end collimator 6071 is composed of a collimator and an input optical fiber 607 therein; the output end collimator 6081 is composed of a collimator and an output optical fiber 608 therein. The input end collimator 6071, the output end collimator 6081, and the λ / 4 wave plate 602 are fixed on the heat sink 604 using a fixing bracket 609. The fixing bracket 609 and the heat sink 604 are designed as an integrated structure. The thermistor 605 is fixed on the heat sink 604 using a high thermal conductivity glue. The heat sink 604 is fixed on the semiconductor refrigerator 603. The semiconductor refrigerator 603 is fixed in the metal shell 606. Holes are opened at both ends of the shell 606, and the input optical fiber and the output optical fiber are led out from the openings on both sides. The input optical fiber and the output optical fiber are fixed and sealed with low-stress silicone. The top of the shell is sealed with a metal cover. The integrated wave plate device provided by this solution can be used to manufacture, package, test and use the "λ / 4 wave plate" separately, making it an independent optical device, realizing mass production of wave plates, and solving the problem of customization of optical fiber sensing rings. Combined with the solutions in the aforementioned embodiments, the integrated wave plate device provided by this solution can realize the prefabrication and adjustment of the phase delay angle. In addition, the pigtail in the integrated wave plate device provided by this solution can be made into a fiber optic jumper to facilitate connection with an external optical fiber.

[0165] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0166] The above are only the principles and preferred embodiments of the present application. It should be noted that, for ordinary technicians in this field, on the basis of the principles of the present application, several other modifications can be made, which should also be considered as the protection scope of the present application.

Claims

1. A robust enhanced high-precision optical fiber current sensor, characterized in that: include: An optical path module, comprising: a light source, a fiber coupler, a fiber polarizer, a spectrum collection module, a phase modulator, an integrated wave plate device and a photodetector connected in sequence; wherein the integrated wave plate device comprises a λ / 4 wave plate, a thermistor, a quartz substrate, a semiconductor refrigerator, a heat sink and a housing; light emitted by the light source enters the fiber coupler, one output end of the fiber coupler is connected to the fiber polarizer, the other output end of the fiber coupler is connected to the spectrum collection module, and the spectrum collection module collects spectrum information at the output end of the fiber coupler; An optical fiber sensing ring, comprising an optical fiber sensing ring and a reflector, wherein one end of the optical fiber sensing ring is connected to the integrated wave plate device, and the reflector is arranged at the other end of the optical fiber sensing ring; the optical fiber sensing ring surrounds the outside of a current-carrying conductor, and the current-carrying conductor transmits a current to be measured; The circuit module comprises a first control unit and a second control unit, wherein: The first control unit is connected to the photodetector, receives the electrical signal output by the photodetector and analyzes it to obtain the current value of the current-carrying conductor and the optical power value received by the photodetector, wherein the optical power value is used to determine the modulation signal of the phase modulator; The second control unit comprises: A light source control circuit controls the core of the light source to operate at a set operating temperature and a driving current, so that the average wavelength of the light source is maintained at the set average wavelength, and the output optical power of the light source is constant at a preset power; An integrated wave plate device control circuit determines the actual temperature of the integrated wave plate device according to the resistance value of the thermistor, and controls the operating temperature of the semiconductor refrigerator so that the integrated wave plate device operates at a target temperature; A sensing optical fiber temperature acquisition circuit is used to obtain the temperature value of the sensing optical fiber; The spectrum acquisition digital output signal conversion module receives the spectrum information acquired by the spectrum acquisition module and analyzes it to obtain spectrum data; The second signal processing subunit obtains a corrected demodulated current value according to the current value of the current-carrying conductor, the temperature value of the sensing optical fiber, the spectral data and the optical power value, combined with a preset data correspondence list therein; the data correspondence is a correspondence between the current value of the current-carrying conductor, the temperature value of the sensing optical fiber, the optical power value and the demodulated current value obtained according to a calibration test.

2. The robust enhanced high-precision optical fiber current sensor according to claim 1, characterized in that: Also includes polarization-maintaining fiber delay loops: The output fiber of the phase modulator is connected to the input fiber of the polarization-maintaining fiber delay ring at 0°, and the output fiber of the polarization-maintaining fiber delay ring is connected to the input fiber of the integrated wave plate device at 0°.

3. The robust enhanced high-precision optical fiber current sensor according to claim 1, characterized in that: The output end optical fiber of the optical fiber polarizer and the input end optical fiber of the phase modulator are connected with each other by 45 degrees.

4. The robust enhanced high-precision optical fiber current sensor according to claim 1, characterized in that: The output end optical fiber of the integrated wave plate device is connected to the sensing optical fiber by using 0° axis alignment.

5. The robust enhanced high-precision optical fiber current sensor according to claim 1, characterized in that: Also includes: A temperature sensor is used to detect the temperature value of the sensing optical fiber and send it to the sensing optical fiber temperature acquisition circuit.

6. The robust enhanced high-precision optical fiber current sensor according to any one of claims 1 to 5, characterized in that: The first control unit also includes: A preamplifier circuit, whose input end receives the electrical signal output by the photodetector and amplifies it into a voltage signal; A / D conversion circuit, converting the voltage signal into a digital signal; A first signal processing subunit receives the digital signal and parses out the current value of the current-carrying conductor and the optical power value, and generates a digital value corresponding to the phase feedback signal; the first signal processing subunit outputs the current value of the current-carrying conductor; The D / A conversion circuit receives the digital value corresponding to the phase feedback signal and converts it into an analog signal. The analog signal is applied to the phase modulator as a modulation signal.

7. A control method for the robust enhanced high-precision fiber optic current sensor according to any one of claims 1 to 6, characterized in that: include: Controlling the tube core temperature and driving current of the light source to ensure that the average wavelength of the light source is maintained at a set average wavelength and the output optical power of the light source is constant at a preset power; Controlling the temperature of the integrated wave plate device to a target temperature, wherein the target temperature makes the measurement error of the integrated wave plate device at the temperature equal in magnitude and opposite in sign to the measurement error of the sensing optical fiber at the same temperature; Error compensation correction is performed on the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber.

8. The control method of the robust enhanced high-precision optical fiber current sensor according to claim 7, characterized in that: The controlling of the tube core temperature and the driving current of the light source to ensure that the average wavelength of the light source is maintained at a set average wavelength and the output optical power of the light source is constant at a preset power includes: Establishing a light source control model, wherein the light source control model includes the corresponding relationship between the output optical power, average wavelength, and core temperature of the light source and the driving current; According to the light source control model, by controlling the core temperature and driving current of the light source, the average wavelength output by the light source is kept constant at the set average wavelength, and the output optical power of the light source is kept constant at the preset power.

9. The control method of the robust enhanced high-precision optical fiber current sensor according to claim 7, characterized in that: The method of controlling the tube core temperature and driving current of the light source to ensure that the average wavelength of the light source is maintained at a set average wavelength and the output optical power of the light source is constant at a preset power also includes: According to the spectrum data collected by the spectrum acquisition module, the measured wavelength of the light source is obtained; Obtaining a difference between the measured wavelength and the set average wavelength; In combination with the preset multidimensional parameter model and the difference, the core temperature and the driving current of the light source are adjusted so that the average wavelength output by the light source is constant at the set average wavelength, and the output optical power of the light source is constant at the preset power output optical power; wherein the multidimensional parameter model is used to record the output optical power of the light source, the average wavelength of the light source, and the corresponding relationship between the core temperature and the driving current.

10. The control method of the robust enhanced high-precision optical fiber current sensor according to claim 7, characterized in that: The controlling the temperature of the integrated wave plate device to be at a target temperature, wherein the target temperature makes the measurement error of the integrated wave plate device equal in magnitude and opposite in sign to the measurement error of the sensing optical fiber, comprises: Model the measurement error of the integrated wave plate device at different temperatures to obtain the measurement error model of the integrated wave plate device; Modeling the measurement error of the sensing optical fiber at different temperatures to obtain the measurement error model of the sensing optical fiber at different temperatures; According to the measured temperature of the sensing optical fiber, a corresponding sensing optical fiber error value is obtained based on the sensing optical fiber measurement error model; Taking the inverse of the sensor optical fiber error value as the target error value of the integrated wave plate device; The target temperature of the integrated wave plate device is obtained based on the target error value of the integrated wave plate device and the integrated wave plate measurement error model, and the operating temperature of the semiconductor refrigerator is controlled so that the operating temperature of the integrated wave plate device is the target temperature.

11. The control method of the robust enhanced high-precision optical fiber current sensor according to claim 7, characterized in that: The error compensation correction of the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber includes: Modeling the wavelength drift of the integrated wave plate device includes: changing the average wavelength of the light source input into the integrated wave plate device at different constant temperatures, and testing the measurement error caused by the different average wavelengths of the light sources; or changing the average wavelength of the light source input into the integrated wave plate device at different constant temperatures, and testing the phase delay angle change of the integrated wave plate device caused by the different average wavelengths of the light sources, and determining the measurement error according to the phase delay angle change; modeling according to the measurement results to obtain a wavelength drift error model of the integrated wave plate device at different constant temperatures; According to the spectrum data collected by the spectrum collection module, the measured average wavelength of the light source is obtained; According to the wavelength drift error model of the integrated wave plate device corresponding to the target temperature and combined with the measured average wavelength of the light source, an error compensation coefficient of the integrated wave plate device is obtained; the error compensation coefficient of the integrated wave plate device is sent to the second control unit for the second signal processing subunit to correct the demodulated current value.

12. The control method of the robust enhanced high-precision optical fiber current sensor according to claim 11, characterized in that: The error compensation correction of the wavelength drift of the integrated wave plate device and the wavelength drift of the sensing optical fiber also includes: Get the corresponding relationship between the average wavelength of the light source, the fiber Verdet constant and the measurement error: Where V is the fiber Verdet constant, λ c is the average wavelength of the light source, is the phase difference, ε is the measurement error; Obtaining the wavelength drift of the sensing optical fiber according to the corresponding relationship and the measured wavelength of the light source; An error compensation coefficient of the sensitivity of the sensing fiber is obtained according to the wavelength drift of the sensing fiber; the error compensation coefficient of the sensitivity of the sensing fiber is sent to the second control unit for the second signal processing subunit to correct the demodulated current value.

13. A packaging process for an integrated wave plate device in a robust enhanced high-precision fiber optic current sensor according to any one of claims 1 to 6, characterized in that: include: Grooving a quartz substrate; Placing the λ / 4 wave plate and the optical fibers at both ends thereof in the grooves opened on the quartz substrate and fixing them; The quartz substrate is disposed on a heat sink, a thermistor is disposed on at least one side of the quartz substrate, and the size of the heat sink is larger than the size of the quartz substrate; The heat sink is arranged on a semiconductor refrigerator, the size of the semiconductor refrigerator is greater than or equal to the size of the heat sink; The semiconductor refrigerator is arranged in a shell, and the optical fibers at both ends are respectively led out from the fiber outlet holes at both ends of the shell and fixed; Put the upper cover of the shell on and seal it with welding or sealant.

14. The packaging process of the integrated wave plate device in the robust enhanced high-precision fiber optic current sensor according to claim 13, characterized in that: The λ / 4 wave plate and the optical fibers at both ends are placed in the grooves opened on the quartz and fixed: the λ / 4 wave plate and the optical fibers at both ends are fixed by UV glue in a point-by-point fixing manner; The semiconductor refrigerator is arranged in a shell, and the optical fibers at the two ends are respectively led out from the fiber outlet holes at the two ends of the shell and fixed: silicone rubber is used to fix the optical fibers at the fiber outlet holes at the two ends of the shell.

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