A temperature error control device and method for a fiber-optic direct current large current sensor

Abstract

The application discloses a kind of optical fiber DC large current sensor temperature error control device and method, and 1 / 4 wave plate and mirror are installed in temperature control box, and temperature control box can be set to target temperature in the temperature range of-40-85 ℃.Since the phase angle of 1 / 4 wave plate is related to temperature, its phase angle will deviate from 90 degrees, and with the change of ambient temperature, the deviation also changes. After the completion of 1 / 4 wave plate in the scheme, by setting the appropriate control temperature of temperature control box, the non-linear error of optical fiber DC large current sensor under large current is less than 0.1%, and the phase angle of 1 / 4 wave plate is closest to 90 degrees at this time. Therefore, the non-linear error of optical fiber DC large current sensor can be significantly reduced.

Description

A device and method for controlling the temperature error of a fiber optic DC high-current sensor Technical Field

[0001] This application relates to the field of DC high current measurement, and in particular to a temperature error control device and method for an optical fiber DC high current sensor. Background Technology

[0002] The basic structure of the fiber optic current sensor is shown in Figure 1. It consists of two parts: a data acquisition unit and a sensing fiber optic loop. The data acquisition unit includes optical components such as a light source 11, a detector 12, a coupler 13, a polarizer 14, a phase modulator 15, and a fiber optic delay loop 16, as well as a signal processing circuit 17. The sensing fiber optic loop includes optical components such as a quarter-wave plate 21, a sensing fiber, and a fiber optic reflector 22.

[0003] When fiber optic current sensors are used to measure high DC currents, nonlinear errors can occur. The main factor affecting these nonlinear errors is the delay angle of the quarter-wave plate, which is temperature-dependent. Currently, the common practice is to install a temperature sensor near the sensing fiber and perform error compensation based on the fiber temperature. However, in high DC current measurement applications, the large structural size and significant heat generation on the busbar can cause uneven heating of the sensing fiber, making it difficult to achieve high-precision compensation. For these reasons, excessively high temperatures or poor stability can lead to errors in fiber optic current sensors. Summary of the Invention

[0004] The technical problem to be solved by this application is the impact of temperature changes on the nonlinear error of existing fiber optic DC high-current sensors. To this end, this application proposes a temperature error control device and method for fiber optic DC high-current sensors.

[0005] To address the aforementioned technical problems, this application provides the following technical solution:

[0006] This application provides a temperature error control device for a fiber optic DC high-current sensor, comprising:

[0007] A temperature control box, suitable for housing a quarter-wave plate and a reflector, wherein the temperature inside the temperature control box is a target temperature, which is within the temperature range of -40 to 85°C; the temperature control box is equipped with an optical fiber through-hole for the sensing optical fiber to pass through.

[0008] In some solutions, the temperature error control device for fiber optic DC high-current sensors includes a temperature control box comprising:

[0009] A thermoelectric cooler is disposed inside a temperature control box. When a current in a first direction passes through the thermoelectric cooler, the thermoelectric cooler performs a cooling function; when a current in a second direction passes through the thermoelectric cooler, the thermoelectric cooler performs a heating function.

[0010] A temperature sensor, located inside the temperature control box, is used to detect the actual temperature value inside the temperature control box;

[0011] The PID controller receives the actual temperature value sent by the temperature sensor and controls the PWM drive circuit based on the difference between the actual temperature value and the target temperature.

[0012] The PWM drive circuit, under the control of the PID controller, adjusts the direction and magnitude of the current flowing through the semiconductor cooling chip.

[0013] The temperature error control device for fiber optic DC high-current sensors described in some solutions also includes:

[0014] An optical fiber sheath covers the outside of the sensing optical fiber of the optical fiber current sensor.

[0015] A spiral coil is wound around the outside of the optical fiber sheath;

[0016] An alternating current source is connected to the spiral coil to input alternating current into the spiral coil.

[0017] In some solutions, the temperature error control device for fiber optic DC high current sensors has the spiral coil uniformly wound around the outside of the fiber optic sleeve.

[0018] In some solutions, the temperature error control device for fiber optic DC high current sensors has a spiral coil wound around the outside of the fiber optic sleeve with a number of turns within a set range.

[0019] In some solutions, the fiber optic DC high-current sensor temperature error control device includes a fiber optic sleeve comprising a main sleeve and an auxiliary sleeve, the main sleeve and the auxiliary sleeve having the same structure; the sensing fiber is placed inside the main sleeve; and the helical coil is wound crosswise around the outside of the main sleeve and the auxiliary sleeve.

[0020] Some technical solutions in this application also provide an optical fiber current sensor, including the optical fiber DC high current sensor temperature error control device described in any of the above solutions, and further including a data acquisition unit, a quarter-wave plate, a reflector and a sensing optical fiber, wherein the quarter-wave plate and the reflector are placed in the temperature control box of the temperature error control device.

[0021] In some solutions, the optical fiber current sensor uses a precision current source in the temperature error control device, and the amplitude / frequency of the output current of the precision current source is set as a known quantity.

[0022] This application also provides a temperature control method for an optical fiber current sensor, implemented using the temperature error control device described in any of the above solutions, including:

[0023] The sensing fiber loop of the fiber optic current sensor is placed outside the test conductor.

[0024] A test current, which is a direct current, is supplied to the test conductor.

[0025] Adjust the temperature of the temperature control box and obtain the scaling factor of the fiber optic current sensor in real time;

[0026] If the difference between the scaling factor and the standard value is greater than the set error, the temperature of the temperature control box is adjusted until the difference between the scaling factor and the standard value is less than or equal to the set error, and the current temperature of the temperature control box is obtained.

[0027] The current temperature is used as the target temperature of the temperature control box.

[0028] Some of the fiber optic DC high-current sensor temperature error control methods described in the solutions also include:

[0029] When the target temperature is constant, the nonlinear error of the detection result of the fiber optic current sensor is obtained and the nonlinear error is compensated.

[0030] Some of the fiber optic DC high-current sensor temperature error control methods described in the solutions also include:

[0031] Apply an alternating current I to the helical coil ac .sin(2πft), where I ac Let f be the amplitude of the alternating current, f be the frequency of the alternating current, and t be the time.

[0032] Based on the detection current I of the fiber optic current sensor ct =K.[I dc +I ac [sin(2πft)] yields the calculated value of the scaling factor K; where K is the scaling factor, I dc To test the direct current in the conductor;

[0033] The DC current I is determined based on the calculated value of the scaling factor K. dc The compensation value is used to compensate for the DC current I. dc The output of .

[0034] Some solutions describe temperature error control methods for fiber optic DC high-current sensors:

[0035] The frequency of the output current of the AC current source is not equal to the harmonic frequency or a multiple of the harmonic frequency, where the harmonic frequency is the frequency of the harmonic signal carried in the test current.

[0036] In some solutions, the temperature error control method for fiber optic DC high-current sensors involves determining the DC current I based on the calculated value of the scaling factor K. dc The compensation value is used to compensate for the DC current I. dc The output includes:

[0037] The detection result obtained from the fiber optic current sensor is: I ct =K.[I dc +I ac sin(2πf)];

[0038] Detection results I from the fiber optic current sensor ct Performing a Fourier transform yields: F(ω)=KI ac Where ω = 2πf;

[0039] The detection results from the fiber optic current sensor are obtained by integrating over an entire period:

[0040] ∑I ct =KI dc ;

[0041] The DC current I dc The result after compensation is:

[0042]

[0043] The technical solution of this application has the following technical advantages over the prior art:

[0044] The fiber optic DC high-current sensor temperature error control device and method provided in this application installs a quarter-wave plate and a reflector in a temperature control box. The temperature control box can be set to control the temperature to the target temperature within a temperature range of -40-85℃. Since the phase angle of the quarter-wave plate is temperature-dependent, it will deviate from 90 degrees, and this deviation changes with the ambient temperature. In this application, after the quarter-wave plate is fabricated, by setting a suitable control temperature in the temperature control box, the nonlinear error of the fiber optic DC high-current sensor under high current is made less than 0.1%, at which point the phase angle of the quarter-wave plate is closest to 90 degrees. Therefore, the nonlinear error of the fiber optic DC high-current sensor can be significantly reduced. Attached Figure Description

[0045] The preferred embodiments of this application will be described in detail below with reference to the accompanying drawings, which will help to understand the purpose and advantages of this application, wherein:

[0046] Figure 1 is a schematic diagram of the fiber optic current sensor.

[0047] Figure 2 is a schematic diagram of the scaling factor curve involved in the embodiment of this application;

[0048] Figure 3 is a schematic diagram of the structure of the temperature control device for the fiber optic current sensor provided in the embodiment of this application;

[0049] Figure 4 is a schematic diagram of the structure of the fiber optic current sensor, which includes a temperature control device with a fiber optic current sensor, provided in the embodiment of this application.

[0050] Figure 5 is a schematic diagram of the structure of the main sleeve and auxiliary sleeve with an externally wound spiral coil provided in an embodiment of this application;

[0051] Figure 6 is a flowchart of a temperature control method for an optical fiber current sensor according to an embodiment of this application. Detailed Implementation

[0052] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0055] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0056] Fiber optic current sensors are current sensors based on the Faraday magneto-optical effect. The sensing part is made of fiber optic structure and has the advantages of strong resistance to electromagnetic interference, simple insulation, large dynamic range and small size. They have broad application prospects in the field of current measurement in complex electromagnetic environments such as ultra-high voltage power grids, metallurgy and nuclear physics.

[0057] Figure 2 shows the simulation curves of the effect of the waveplate delay angle on the scaling factor K. A deviation of the waveplate delay angle from 90 degrees introduces nonlinear errors. The greater the deviation of the waveplate phase delay angle from 90 degrees, the more pronounced the nonlinear characteristics of the introduced scaling factor become. A waveplate delay angle of 99 degrees introduces a nonlinear error exceeding 1%. Quarter-waveplates are typically fabricated by cutting a section of birefringent fiber, and it is difficult to guarantee a 90-degree cutting angle after fusion splicing. Furthermore, the waveplate delay angle is temperature-dependent. The calculation model is as follows:

[0058] δ=Δβ0L0[1+C1(T-T0)];

[0059] In the formula, Δβ0 is the difference between the propagation constants of the fast and slow axes of the waveplate fiber at room temperature, L0 is the length of the waveplate fiber at room temperature, T is the ambient temperature, T0 is the room temperature, and C1 is the temperature coefficient of the phase delay angle of the waveplate fiber. Therefore, ensuring the stability of the temperature difference between the ambient temperature and room temperature can keep the waveplate delay angle δ within the required range.

[0060] This application provides a temperature error control device for a fiber optic DC high current sensor. Referring to Figures 1, 3, and 4, it includes a temperature control box, which is suitable for placing a quarter-wave plate and a reflector. The temperature inside the temperature control box is at a target temperature, which is within the temperature range of -40 to 85°C. The temperature control box is equipped with a fiber optic through-hole for the sensing fiber to pass through.

[0061] In the above scheme, the quarter-wave plate and reflector are installed in a temperature control box, which can be set to control the temperature to the target temperature within a range of -40-85℃. Since the phase angle of the quarter-wave plate is temperature-dependent, it will deviate from 90 degrees, and this deviation changes with the ambient temperature. In this application's scheme, after the quarter-wave plate is fabricated, by setting a suitable control temperature for the temperature control box, the nonlinear error of the fiber optic DC high-current sensor under high current is made less than 0.1%, at which point the phase angle of the quarter-wave plate is closest to 90 degrees. Therefore, the nonlinear error of the fiber optic DC high-current sensor can be significantly reduced.

[0062] As shown in Figure 3, in a specific implementation, the fiber optic DC high-current sensor temperature error control device includes a temperature control box comprising a thermoelectric cooler 101 disposed inside the temperature control box. When a current flows through the thermoelectric cooler 101 in a first direction, the thermoelectric cooler 101 performs a cooling function; when a current flows through the thermoelectric cooler 101 in a second direction, the thermoelectric cooler 101 performs a heating function. A temperature sensor 102 is disposed inside the temperature control box to detect the actual temperature value inside the temperature control box. A PID controller receives the actual temperature value sent by the temperature sensor and controls a PWM drive circuit based on the difference between the actual temperature value and the target temperature. The PWM drive circuit, under the control of the PID controller, adjusts the direction and magnitude of the current flowing through the thermoelectric cooler 101. A data acquisition circuit can be configured between the temperature sensor 102 and the PID controller support; this data acquisition circuit can be a bridge circuit. To ensure a constant temperature for the waveplate, a thermoelectric cooler 101 can be used to control its temperature. The temperature sensor 102 can be implemented using a thermistor, which monitors the waveplate temperature. Together with the thermoelectric cooler 101 and an external controller, they form a constant temperature control system. The system structure based on the PWM control scheme is shown in the figure. The output stage employs PWM modulation technology, achieving an output efficiency of over 80%. This scheme only requires controlling the direction and magnitude of the current to the thermoelectric cooler using a PWM drive circuit, thereby controlling the temperature within the temperature control box. The structure is simple.

[0063] Further, as shown in Figure 4, the fiber optic DC high-current sensor temperature error control device also includes a fiber optic sleeve 201, covering the sensing fiber of the fiber optic current sensor; a spiral coil 202, wound around the outside of the fiber optic sleeve; and an AC current source connected to the spiral coil 202, inputting AC current into the spiral coil 202. The fiber optic sleeve 201 is used to protect the sensing fiber and is a protective tube with a diameter of 1-2 mm. The spiral coil 202 is uniformly wound around the outside of the fiber optic sleeve 201, with N turns, which is selected within a set range of 1000-10000 turns. In this scheme, the error of the fiber optic current sensor is calibrated and corrected online by applying AC current through the spiral coil 202. The uniform winding of the spiral coil 202 makes the magnetic field sensed by the fiber more uniform, overcoming the error caused by uneven fiber temperature. The above-mentioned solution in this application can overcome the nonlinear error caused by temperature changes on the quarter-wave plate of the fiber optic DC high-current sensor and reduce the Wilder constant drift error caused by the influence of temperature changes on the sensing fiber. It reduces the impact of temperature changes on the fiber optic DC high-current sensor in two ways, thereby achieving a measurement accuracy better than 0.1% in field applications.

[0064] Referring to Figures 5 and 4, the fiber optic sleeve 201 in this scheme includes a main sleeve 2011 and an auxiliary sleeve 2012, with the main sleeve 2011 and the auxiliary sleeve 2012 having the same structure. The sensing fiber G is placed inside the main sleeve 2011, and the spiral coil 202 is wound crosswise around the outside of the main sleeve 2011 and the auxiliary sleeve 2012. As shown in Figure 5, when the spiral coil 202 is wound uniformly and crosswise around the main sleeve and the auxiliary sleeve, the magnetic flux generated by the main sleeve and the magnetic flux generated by the auxiliary sleeve have opposite directions and can cancel each other out. After the main sleeve and the auxiliary sleeve surround the test conductor, when a DC current passes through the test conductor, it will not be affected by the magnetic flux of the AC current in the spiral coil and thus will not generate an induced current, thereby ensuring the accuracy of the detection results of the fiber optic current sensor.

[0065] In some embodiments, an optical fiber current sensor is also provided, including the optical fiber DC high current sensor temperature error control device described in any of the above schemes, and further including a data acquisition unit, a quarter-wave plate, a reflector, and a sensing optical fiber, wherein the quarter-wave plate and the reflector are placed in the temperature control box of the temperature error control device. Further, the AC current source in the temperature error control device is a precision current source, and the amplitude / frequency of the output current of the precision current source is set as a known quantity. Alternatively, its amplitude and frequency are measured by a precision instrument, and the result of the precision instrument measurement is used as a known quantity. The optical fiber current sensor in this application controls the temperature of the quarter-wave plate to a specific temperature, reducing the nonlinear error of the optical fiber current sensor to within 0.1%, performing nonlinear compensation to further reduce the nonlinear error of the optical fiber current sensor to within 0.1%, and applying AC current through a spiral coil to perform online calibration and correction of the error of the optical fiber current sensor. Therefore, the above method of this application can overcome the influence of temperature changes on the nonlinear error and Wilder constant drift error of the optical fiber DC high current sensor, thereby obtaining a measurement accuracy better than 0.1% in field applications.

[0066] In some solutions, as shown in Figure 6, a temperature control method for an optical fiber current sensor is provided, which is implemented using the optical fiber DC high current sensor temperature error control device described in any of the above solutions, including:

[0067] Step 1: Place the sensing fiber ring of the fiber optic current sensor around the outside of the test conductor.

[0068] Step 2: Control the flow of test current through the test conductor, wherein the test current is a direct current.

[0069] Step 3: Adjust the temperature of the temperature control box and obtain the scaling factor of the fiber optic current sensor in real time.

[0070] Step 4: If the difference between the scaling factor and the standard value is greater than the set error, continue to adjust the temperature of the temperature control box until the difference between the scaling factor and the standard value is less than or equal to the set error, and obtain the current temperature of the temperature control box.

[0071] Step 5: Use the current temperature as the target temperature of the temperature control box.

[0072] After the quarter-wave plate is fabricated, this scheme sets a suitable control temperature for the temperature control box, so that the nonlinear error of the fiber optic DC high-current sensor under high current is less than 0.1%. At this time, the phase angle of the quarter-wave plate is closest to 90 degrees.

[0073] Preferably, when the target temperature is a constant temperature, the nonlinear error of the detection result of the fiber optic current sensor is acquired and compensated. That is, compensation can also be used to address the nonlinear error of the fiber optic current sensor. In this case, the temperature control temperature can be set to a constant value, typically close to the ambient temperature, to keep the temperature control box in a favorable thermal environment, such as 25°C. After setting the temperature control temperature, the temperature control box is put into normal temperature control operation. Current points at 100%, 50%, 20%, 10%, and 1% of the maximum current are selected, and the scaling factor of the fiber optic current sensor is measured. Based on the detection points, a fitted curve can be obtained using an existing curve fitting method, which is then used for nonlinear software compensation.

[0074] More preferably, the temperature control method for the fiber optic current sensor further includes:

[0075] Step 5: Apply alternating current I to the spiral coil ac .sin(2πft), where I ac Here, f is the amplitude of the alternating current, f is the frequency of the alternating current, and t is time.

[0076] Step Six: Based on the detected current I of the fiber optic current sensor ct =K.[I dc +I ac [sin(2πft)] yields the calculated value of the scaling factor K; where K is the scaling factor, I dc To test the direct current in the conductor;

[0077] Step 7: Determine the DC current I based on the calculated value of the scaling factor K. dc The compensation value is used to compensate for the DC current I. dc The output current of the AC current source is further preferably not equal to the harmonic frequency or a multiple of the harmonic frequency, wherein the harmonic frequency is the frequency of the harmonic signal carried in the test current.

[0078] Even after controlling the nonlinear error to within 0.1% using a temperature-controlled waveplate, the Wilder constant of the fiber optic sensor will still drift with temperature. Since the measured current is DC, online compensation can be achieved by applying an AC current NI to the uniform helical coil using an AC current source, where N is the number of turns of the helical coil and I is the output current of the AC current source. After applying the AC current, the output of the fiber optic current sensor is the measured DC current I. dc The superimposed excitation AC current I ac The magnitude of the alternating current can be separated using Fourier transform. By comparing this with the applied alternating current, the error can be calculated and compensated online. Considering that the DC current output by the rectifier may contain 50Hz and higher harmonics, the frequency of the applied current should avoid 50Hz and its harmonics. Specifically, let the applied current from the alternating current source be I. ac sin(2πft), where I ac The amplitude of the applied alternating current is f, where f is the current frequency, such as 70Hz.

[0079] The output of the fiber optic current sensor is: I ct =K.[I dc +I ac sin(2πf)];

[0080] Where I dc K is the DC current being measured, and K is the scaling factor of the fiber optic current sensor. When there is no error, K = 1, and when there is an error, the value of K will deviate from 1.

[0081] First, calculate the value of K, since I ac And f are known quantities, for I ct Performing a Fourier transform yields F(ω) = KI ac Where ω = 2πf;

[0082] but

[0083] Since the output of the fiber optic current sensor contains an AC signal, integrating it over an entire cycle can eliminate the AC current.

[0084] ∑I ct =KI dc ;

[0085] By correcting the integral current with a K value, the true measured current I can be calculated. dc .

[0086]

[0087] Using the above method, the quarter-wave plate is temperature-controlled to a specific temperature, reducing the nonlinear error of the fiber optic current sensor to within 0.1%; the quarter-wave plate is temperature-controlled to a constant temperature and nonlinear compensation is performed, further reducing the nonlinear error of the fiber optic current sensor to within 0.1%; AC current is applied through a helical coil to perform online calibration and correction of the fiber optic current sensor error; uniform winding of the helical coil can make the magnetic field sensed by the fiber more uniform, overcoming the error caused by uneven fiber temperature.

[0088] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for controlling the temperature error of a fiber optic DC high-current sensor, implemented using a temperature error control device, characterized in that: The temperature error control device includes a temperature control box, which is suitable for placing a quarter-wave plate and a reflector. The temperature inside the temperature control box is at a target temperature, which is within the temperature range of -40 to 85°C. The temperature control box is equipped with an optical fiber through-hole for the sensing optical fiber to pass through; the method includes: placing the sensing optical fiber ring of the optical fiber current sensor around the test conductor; controlling the test conductor to pass a test current, the test current being a direct current; adjusting the temperature of the temperature control box and acquiring the scaling factor of the optical fiber current sensor in real time; if the difference between the scaling factor and the standard value is greater than a set error, then continuing to adjust the temperature of the temperature control box until the difference between the scaling factor and the standard value is less than or equal to the set error, and acquiring the current temperature of the temperature control box; and using the current temperature as the target temperature of the temperature control box.

2. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 1, characterized in that, Also includes: When the target temperature is constant, the nonlinear error of the detection result of the fiber optic current sensor is obtained and the nonlinear error is compensated.

3. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 2, characterized in that, Also includes: Apply alternating current to the spiral coil , among which, I ac Let f be the amplitude of the alternating current, f be the frequency of the alternating current, and t be the time; based on the current detected by the fiber optic current sensor... Obtain the calculated value of the scaling factor K; where K is the scaling factor, I dc To test the direct current in the conductor; the direct current I is determined based on the calculated value of the scaling factor K. dc The compensation value is used to compensate for the DC current I. dc The output of .

4. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 3, characterized in that: The frequency of the output current of the AC current source is not equal to the harmonic frequency or a multiple of the harmonic frequency, where the harmonic frequency is the frequency of the harmonic signal carried in the test current.

5. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 3 or 4, characterized in that, The DC current I is determined based on the calculated value of the scaling factor K. dc The compensation value is used to compensate for the DC current I. dc The output includes: obtaining the detection results from the fiber optic current sensor. ; Detection results of the fiber optic current sensor I ct Performing a Fourier transform yields: ;in, ； The detection results from the fiber optic current sensor are obtained by integrating over an entire period: The DC current I dc The result after compensation is: 。 6. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 1, characterized in that, The temperature control box includes: a thermoelectric cooler, disposed inside the temperature control box, wherein the thermoelectric cooler performs a cooling function when a current in a first direction flows through it, and performs a heating function when a current in a second direction flows through it; a temperature sensor, disposed inside the temperature control box, for detecting the actual temperature value inside the temperature control box; a PID controller, which receives the actual temperature value sent by the temperature sensor and controls a PWM drive circuit based on the difference between the actual temperature value and the target temperature; the PWM drive circuit, under the control of the PID controller, adjusts the direction and magnitude of the current flowing through the thermoelectric cooler.

7. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 6, characterized in that, Also includes: An optical fiber sheath covers the outside of the sensing optical fiber of the optical fiber current sensor. A spiral coil is wound around the outside of the optical fiber sheath; An alternating current source is connected to the spiral coil to input alternating current into the spiral coil.

8. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 7, characterized in that: The spiral coil is evenly wound around the outside of the optical fiber sheath.

9. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 8, characterized in that: The number of turns of the spiral coil wound around the outside of the optical fiber sheath is within a set number of turns.

10. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 9, characterized in that: The optical fiber sheath includes a main sheath and an auxiliary sheath, the main sheath and the auxiliary sheath having the same structure; the sensing optical fiber is placed inside the main sheath; the helical coil is wound crosswise around the outside of the main sheath and the auxiliary sheath.

11. The method for controlling the temperature error of a fiber optic DC high-current sensor according to claim 10, characterized in that: The AC current source is a precision current source, and the amplitude / frequency of the output current of the precision current source is set as a known quantity.

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