Pipeline triaxial stress internal detection circuit and device based on tunnel magnetic resistance

Abstract

The utility model relates to a pipeline triaxial stress internal detection circuit and device based on tunnel magnetoresistance, and the circuit comprises a square wave generation circuit, a first high-pass filter circuit, a first low-pass filter circuit, an excitation signal generation circuit, a reference signal generation circuit, and a tunnel magnetoresistance sensor detection circuit. Square waves generated by the square wave generation circuit are converted into sine waves through the first high-pass filter circuit and the first low-pass filter circuit in sequence, the sine waves are input into the excitation signal generation circuit, and the excitation signal generation circuit is connected with the reference signal generation circuit and the tunnel magnetoresistive sensor detection circuit. The tunnel magnetoresistive sensor detection circuit comprises phase-sensitive detection circuits, the output of the reference signal generation circuit is connected to the phase-sensitive detection circuits respectively, and the tunnel magnetoresistive sensor detection circuit is arranged in three directions to form a pipeline triaxial stress internal detection circuit. Compared with the prior art, the device has the advantages of high detection precision, strong practicability and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to oil and gas pipeline internal detection technical field especially pipeline triaxial stress internal detection circuit and device based on tunnel magnetoresistance. BACKGROUND

[0002] Oil and gas pipeline is buried in the ground for a long time, and stress concentration area is formed under the action of soil, medium pressure and self gravity. In the stress concentration area, stress corrosion cracking and yield failure are prone to occur due to defects such as mechanical damage, corrosion and crack of the pipeline body, which brings great risk to the pipeline safety. Therefore, internal stress detection of buried pipeline is an important step of pipeline operation and maintenance.

[0003] The medium commonly used in oil and gas pipeline is ferromagnetic material. When the material is processed through melting, forging and heat treatment, the magnetic domain organization in the pipeline will be disintegrated, and the magnetism will disappear. When the pipeline is buried in the ground, the internal magnetic domain organization of the pipeline will be oriented and irreversibly reoriented under the action of stress load in the geomagnetic environment, and the weak geomagnetic field will form the change of leakage magnetic field in the stress concentration area. By measuring the axial, radial and normal components of the leakage magnetic field on the surface of the ferromagnetic pipeline, the stress concentration area of the oil and gas pipeline can be determined.

[0004] Therefore, how to measure the axial, radial and normal components of the leakage magnetic field on the surface of the ferromagnetic pipeline is of great significance to improve the measurement accuracy of the stress concentration area of the oil and gas pipeline. UTILITY MODEL CONTENT

[0005] The utility model discloses a kind of pipeline triaxial stress internal detection circuit and device based on tunnel magnetoresistance for overcoming the defects of the above prior art, for measuring the leakage magnetic field component of ferromagnetic pipeline surface.

[0006] The purpose of the utility model can be realized by the following technical solutions:

[0007] The application discloses a tunnel magnetoresistance-based pipeline triaxial stress internal detection circuit, which comprises a square wave generating circuit, a first high-pass filter circuit, a first low-pass filter circuit, an excitation signal generating circuit, a reference signal generating circuit, an X-axis tunnel magnetoresistance sensor detection circuit, a Y-axis tunnel magnetoresistance sensor detection circuit and a Z-axis tunnel magnetoresistance sensor detection circuit, a square wave generated by the square wave generating circuit is converted into a sine wave through the first high-pass filter circuit and the first low-pass filter circuit in sequence, the sine wave is input into the excitation signal generating circuit, the excitation signal generating circuit is connected with the reference signal generating circuit, the X-axis tunnel magnetoresistance sensor detection circuit, the Y-axis tunnel magnetoresistance sensor detection circuit and the Z-axis tunnel magnetoresistance sensor detection circuit respectively, the X-axis tunnel magnetoresistance sensor detection circuit, the Y-axis tunnel magnetoresistance sensor detection circuit and the Z-axis tunnel magnetoresistance sensor detection circuit all comprise a phase-sensitive detection circuit, and the output of the reference signal generating circuit is connected to each phase-sensitive detection circuit.

[0008] Further, the output of the excitation signal generating circuit is a sine wave excitation signal, the reference signal generating circuit converts the sine wave excitation signal into a reverse signal of the same frequency as the sine wave excitation signal and outputs the reverse signal.

[0009] Further, the phase-sensitive detection circuit comprises a multiplier and a second low-pass filter circuit connected in sequence, one input end of the multiplier is connected to the reference signal generating circuit, the other input end is connected to the excitation signal generating circuit through a pre-circuit, and the output end of the second low-pass filter circuit is connected to a post-circuit.

[0010] Further, the pre-circuit comprises a tunnel magnetoresistance sensor, an instrument operational amplifier circuit and a second high-pass filter circuit connected in sequence, the input end of the tunnel magnetoresistance sensor is connected to the excitation signal generating circuit, and the output end of the second high-pass filter circuit is connected to the multiplier.

[0011] Further, the multiplier is a four-quadrant analog multiplier, the second low-pass filter circuit is composed of two first-order RC cascades, the input of the multiplier is the output signal of the second high-pass filter circuit and the reference signal of the reference signal generating circuit, the output is a sum frequency signal and a difference frequency signal, and the second low-pass filter circuit filters out the sum frequency signal and retains the difference frequency signal as the output signal of the phase-sensitive detection circuit.

[0012] Further, the tunnel magnetoresistance sensor comprises a first tunnel magnetoresistance element, a second tunnel magnetoresistance element, a third tunnel magnetoresistance element and a fourth tunnel magnetoresistance element, the first tunnel magnetoresistance element and the second tunnel magnetoresistance element are connected in series as a first circuit, the third tunnel magnetoresistance element and the fourth tunnel magnetoresistance element are connected in series as a second circuit, the first circuit and the second circuit are connected in parallel to obtain two parallel connection points, the tunnel magnetoresistance sensor comprises an input end and two output ends, the input end is connected to the excitation signal generating circuit, and the two output ends are connected to the two parallel connection points respectively.

[0013] Further, the instrumentation amplifier amplification circuit comprises a first pin, a second pin, a third pin, a fourth pin and an output end, an output end signal of the tunneling magnetoresistance sensor is input to the first pin, another output end signal of the tunneling magnetoresistance sensor is input to the fourth pin, the second pin and the third pin are connected through a gain resistor, and the output end of the instrumentation amplifier amplification circuit is connected to the second high-pass filter circuit.

[0014] Further, the post-circuit comprises an in-phase amplification circuit.

[0015] Further, the in-phase amplification circuit comprises an amplification circuit and a third low-pass filter circuit, an input signal of the in-phase amplification circuit is amplified through the amplification circuit, and then an output voltage signal is obtained through the third low-pass filter circuit.

[0016] The second aspect of the utility model relates to a pipeline triaxial stress internal detection device based on tunneling magnetoresistance, which comprises a first magnetoresistance sensor, a second magnetoresistance sensor, a third magnetoresistance sensor, a first plane, a second plane and a pipeline triaxial stress internal detection circuit based on tunneling magnetoresistance, the first plane and the second plane are perpendicular to each other, the first magnetoresistance sensor is arranged on the first plane and perpendicular to the intersection line of the first plane and the second plane, the second magnetoresistance sensor is arranged on the second plane and perpendicular to the intersection line of the first plane and the second plane, and the third magnetoresistance sensor is arranged on the first plane and perpendicular to the first magnetoresistance sensor, wherein the X-axis tunneling magnetoresistance sensor detection circuit, the Y-axis tunneling magnetoresistance sensor detection circuit and the Z-axis tunneling magnetoresistance sensor detection circuit are connected with the first magnetoresistance sensor, the second magnetoresistance sensor and the third magnetoresistance sensor respectively.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] 1) the utility model discloses a tunneling magnetoresistance sensor through excitation signal generating circuit as the excitation signal, obtains the output signal of tunneling magnetoresistance sensor, as the input signal of phase sensitive detection circuit, through reference signal generating circuit, the reference signal based on excitation signal is as another input signal of phase sensitive detection circuit, and the direct current detectable signal of tunneling magnetoresistance sensor is obtained through phase sensitive detection circuit, and is used for subsequent instrument detection process, improves the output precision of tunneling magnetoresistance sensor, and improves the determination accuracy of the component of ferromagnetic pipeline surface leakage field.

[0019] 2) the utility model discloses a kind of measurement device based on the circuit of the utility model, and the measurement device structure capable of 3-dimensional space magnetic field detection is formed by two two perpendicular magnetoresistance sensors. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the circuit structure schematic diagram.

[0021] Figure 2 Circuit diagram of the square wave generation circuit for Embodiment 1;

[0022] Figure 3 Circuit diagram of the first high-pass filter circuit for Embodiment 1;

[0023] Figure 4 Circuit diagram of the first low-pass filter circuit for Embodiment 1;

[0024] Figure 5 Circuit diagram of the excitation signal generation circuit for Embodiment 1;

[0025] Figure 6 Circuit diagram of the reference signal generation circuit for Embodiment 1;

[0026] Figure 7 Circuit diagram of the tunnel magnetoresistive sensor for Embodiment 1;

[0027] Figure 8 Circuit diagram of the instrumentation amplifier amplification circuit for Embodiment 1;

[0028] Figure 9 Circuit diagram of the second high-pass filter circuit for Embodiment 1;

[0029] Figure 10 Circuit diagram of the multiplier for Embodiment 1;

[0030] Figure 11 Circuit diagram of the second low-pass filter circuit for Embodiment 1;

[0031] Figure 12 Circuit diagram of the in-phase amplification circuit for Embodiment 1;

[0032] Figure 13 Layout diagram of a single tri-axial stress internal detection probe in Embodiment 2;

[0033] Figure 14 Detector distribution diagram of a plurality of tri-axial stress internal detection probes in Embodiment 3.

[0034] Marked in the figure: 1, square wave generating circuit, 2, first high pass filter circuit, 3, first low pass filter circuit, 4, excitation signal generating circuit, 5, reference signal generating circuit, 6, tunneling magnetic resistance sensor, 7, instrument amplifier amplification circuit, 8, second high pass filter circuit, 9, multiplier, 10, second low pass filter circuit, 11, phase sensitive detection circuit, 12, in-phase amplification circuit, 13, X-axis tunneling magnetic resistance sensor detection circuit, 14, Y-axis tunneling magnetic resistance sensor detection circuit, 15, Z-axis tunneling magnetic resistance sensor detection circuit, 20, first magnetic resistance sensor, 21, second magnetic resistance sensor, 22, third magnetic resistance sensor, 23, first plane, 24, second plane, 30, probe, 31, detector, U1, oscillator, U2A, first operational amplifier, U2B, second operational amplifier, U3, instrument amplifier, U4, multiplier, U5, third operational amplifier, R1, first resistance, R2, second resistance, R3, third resistance, R4, fourth resistance, R5, fifth resistance, R6, sixth resistance, R7, seventh resistance, R8, eighth resistance, R9, ninth resistance, R10, tenth resistance, R11, eleventh resistance, R12, twelfth resistance, R13, thirteenth resistance, R15, fifteenth resistance, R16, sixteenth resistance, R17, seventeenth resistance, R18, eighteenth resistance, C1, first capacitor, C2, second capacitor, C3, third capacitor, C4, fourth capacitor, C5, fifth capacitor, C6, sixth capacitor, C7, seventh capacitor, S1, Wheatstone bridge, CLK, square wave signal, CLK1, first high pass filter circuit output signal, CLK2, sine wave signal, EXC, sine wave excitation signal, OUT1, tunneling magnetic resistance sensor first output signal, OUT2, tunneling magnetic resistance sensor first output signal, AMP, instrument amplifier output signal, SIG, second high pass filter circuit output signal, REF, reference signal, MUL, multiplier output signal, FIL, phase sensitive detection output signal, VOUT, voltage signal. DETAILED DESCRIPTION

[0035] The utility model will be explained in detail below in combination with the drawings and specific embodiments. The embodiment is implemented on the premise of the technical scheme of the utility model, and detailed implementation mode and specific operation process are given, but the protection scope of the utility model is not limited to the following examples.

[0036] Embodiment 1

[0037] As Figure 1As shown, the utility model is a kind of pipeline triaxial stress internal detection circuit based on tunnel magnetoresistance, including square wave generating circuit 1, first high pass filter circuit 2, first low pass filter circuit 3, excitation signal generating circuit 4, reference signal generating circuit 5, X-axis tunnel magnetoresistance sensor detection circuit 13, Y-axis tunnel magnetoresistance sensor detection circuit 14 and Z-axis tunnel magnetoresistance sensor detection circuit 15, square wave generating circuit 1 is converted into sine wave in turn by first high pass filter circuit 2 and first low pass filter circuit 3, and sine wave is input excitation signal generating circuit 4, excitation signal generating circuit 4 is connected with reference signal generating circuit 5, X-axis tunnel magnetoresistance sensor detection circuit 13, Y-axis tunnel magnetoresistance sensor detection circuit 14 and Z-axis tunnel magnetoresistance sensor detection circuit 15 respectively, and X-axis tunnel magnetoresistance sensor detection circuit 13, Y-axis tunnel magnetoresistance sensor detection circuit 14 and Z-axis tunnel magnetoresistance sensor detection circuit 15 all include phase-sensitive detection circuit 11, and the output of reference signal generating circuit 5 is connected to each phase-sensitive detection circuit 11.

[0038] Phase-sensitive detection circuit 11 includes multiplier 9 and second low pass filter circuit 10 connected in sequence, one input of the multiplier 9 is connected to reference signal generating circuit 5, the other input is connected to excitation signal generating circuit 4 through preamplifier circuit, and the output end of the second low pass filter circuit 10 is connected to postamplifier circuit.

[0039] Preamplifier circuit includes tunnel magnetoresistance sensor 6, instrument operational amplifier circuit 7 and second high pass filter circuit 8 connected in sequence, the input end of tunnel magnetoresistance sensor 6 is connected to excitation signal generating circuit 4, and the output end of second high pass filter circuit 8 is connected to multiplier 9.

[0040] Postamplifier circuit includes in-phase amplification circuit 12.

[0041] In the embodiment, each circuit is specifically:

[0042] Square wave generating circuit 1: for generating square wave signal CLK, after being modulated into sine wave, it is loaded into excitation signal generating circuit 4.Square wave frequency needs to avoid low-frequency and power-frequency interference.

[0043] As shown in the drawing, Figure 2 The oscillator U1 of square wave generating circuit 1 is preferably LTC6906, and LTC6906 is a mature technology, which is not limited here.LTC6906 is a SOT-23 package programmable silicon oscillator with micro power and 10kHz to 1MHz resistor setting frequency range, and a single resistor is responsible for setting the oscillator frequency in a 10:1 range, with an initial accuracy better than 0.5%.The output frequency can be divided by 1, 3 or 10 to span a total frequency range of 100:1 (10kHz to 1MHz), and the first resistor R1 is a 160Ω resistor, generating square wave signal CLK.

[0044] The first high-pass filter circuit 2 is used to filter out power frequency and low frequency noise interference signals to obtain a first high-pass filter circuit output signal CLK1.

[0045] The first high-pass filter circuit is composed of C2 and R2, and the output signal of the high-pass filter circuit is CLK1, as shown in the figure. Figure 3 C2 is a 220nf capacitor, R2 is a 3.3kΩ resistor, and the high-pass filter cutoff frequency is 219Hz, which can filter out power frequency 50Hz interference and low frequency interference signals.

[0046] The first low-pass filter circuit 3 filters out high frequency harmonic components of 3 times the fundamental frequency and above in the square wave to obtain a sine wave signal CLK2 with the same frequency as the square wave.

[0047] The first low-pass filter circuit is composed of R3 and C3, as shown in the figure. Figure 4 R3 is a 24kΩ resistor, and C3 is a 22pf capacitor, so the low-pass filter frequency is 301kHz. Since the square wave fundamental frequency is 208kHz, the 3 times the fundamental frequency is 624kHz. Signals above 3 times the fundamental frequency of 624kHz are filtered out. Therefore, the CLK1 signal can obtain a 208kHz sine wave signal CLK2 with the same frequency as the square wave after passing through the circuit.

[0048] The excitation signal generating circuit 4 is used to generate a sine wave excitation signal EXC to drive the tunneling magnetoresistance sensor. As shown in the figure, Figure 5 The sine wave signal CLK2 passes through the second operational amplifier U2B follower circuit to improve the driving ability of the sine wave signal, and the fourth resistor R4 is a 3.3kΩ resistor. The output sine wave excitation signal EXC is used as the excitation signal of the tunneling magnetoresistance sensor.

[0049] The reference signal generating circuit 5 is shown in the figure. Figure 6 The input of the reference signal is the sine wave excitation signal output by the excitation signal generating circuit 4, which passes through the inverting proportional amplification circuit to obtain an inverted signal with the same frequency but different amplitude as the sine wave excitation signal as the reference signal REF input to the phase sensitive detection circuit 11.

[0050] The sine wave excitation signal EXC is applied to the inverting input terminal of the first operational amplifier U2A, and U2A works as an inverting amplifier, whose amplification factor is determined by the resistance values of the fifth resistor R5 and the sixth resistor R6. The reference signal REF is obtained by inverting amplification.

[0051] The tunneling magnetoresistance sensor 6 is shown in the figure. Figure 7As shown, the tunnel magnetoresistance sensor comprises four high-sensitivity tunnel magnetoresistance (TMR) elements, the four TMR elements are divided into two groups, each group comprises two TMR elements connected in series, the two groups are connected in parallel, forming a push-pull Wheatstone full-bridge structure resistance bridge. The output of the Wheatstone bridge is measured between the two parallel connection points, and changes linearly with the leakage magnetic field, obtaining the first output signal OUT1 and the second output signal OUT2 of the tunnel magnetoresistance sensor, which is the working zone of the tunnel magnetoresistance sensor. The tunnel magnetoresistance sensor is preferably a TMR2901 linear sensor, and TMR2901 is a mature technology, which is not limited here.

[0052] The instrumentation amplifier amplification circuit 7 is used to amplify the differential signal of the output of the tunnel magnetoresistance sensor 6, and only follows the common-mode input signal, so that the common-mode rejection ratio of the tunnel magnetoresistance sensor 6 is improved, and the output signal AMP is obtained.

[0053] As shown in Figure 8 , the instrumentation amplifier U3 is AD8421, the built-in resistance is 9.9kΩ, the 4th pin of AD8421 is connected to the parallel connection of OUT1 and the eighth resistance R8, and the 1st pin is connected to the parallel connection of OUT2 and the ninth resistance R9. The eighth resistance R8 and the ninth resistance R9 are both 100kΩ connected to ground, and the tenth resistance R10 is 1.1kΩ, obtaining the instrumentation amplifier output signal AMP.

[0054] The second high-pass filter circuit 8 is used to isolate direct current and power frequency noise, and amplify the effective alternating current signal to obtain the output signal SIG of the second high-pass filter circuit.

[0055] The second high-pass filter circuit is composed of R11 and C4, as shown in Figure 9 . R11 is a 2.5kΩ resistor, and C4 is a 220nf capacitor. The filter frequency of the second high-pass filter circuit is 289Hz.

[0056] The multiplier 9 is used to multiply the output signal SIG of the tunnel magnetoresistance sensor and the reference signal REF.

[0057] As shown in Figure 10 , the multiplier U4 is AD835, which is a four-quadrant analog multiplier. The output is the sum frequency signal component of the output signal of the tunnel magnetoresistance sensor and the reference signal, and the difference frequency signal component of the output signal of the tunnel magnetoresistance sensor and the reference signal. The sum frequency signal component is filtered out by the second low-pass filter circuit 10, so that the difference frequency signal component can be obtained for direct current detection. The multiplier is grounded through R12 and R13.

[0058] The second low-pass filter circuit 10 consists of two cascaded first-order RC circuits. Since this circuit does not use an active filter, the probe size can be reduced.

[0059] The first RC cascade consists of R14 and C5, and the second RC cascade consists of R15 and C6, as follows. Figure 11 As shown. R14 is 1kΩ, C5 is 220nF, R15 is 1kΩ, and C6 is 220nF. Therefore, the low-pass filter cutoff frequency is 732Hz. The difference frequency signal component between the output signal and the reference signal of the tunnel magnetoresistive sensor can be preserved so that it can be detected by DC.

[0060] Phase-sensitive detection circuit 11 consists of multiplier 9 and second low-pass filter circuit 10. Multiplier 9 obtains the sum and difference frequency signals MUL of the tunnel magnetoresistive sensor's output signal SIG and the reference signal REF. By using the low-pass filter to filter out the sum frequency component of the tunnel magnetoresistive sensor's output signal and the reference signal, the difference frequency component FIL of the tunnel magnetoresistive sensor's output signal and the reference signal can be obtained. This signal can be detected by DC. Simultaneously, the low-pass filter circuit can also filter out environmental noise.

[0061] In-phase amplifier circuit 12: Amplifies the output signal FIL of the phase-sensitive detector so that the amplified effective tunnel magnetoresistive signal VOUT is output. VOUT is a voltage signal, and subsequent instruments can acquire the voltage signal VOUT output by the triaxial stress detection probe through the analog output signal.

[0062] like Figure 12 As shown, the non-inverting amplifier circuit consists of a third operational amplifier U5 and resistors R16, R17, R18, and capacitor C7. The amplifier circuit formed by resistors R16 and R17 has a magnification ratio of 6, and resistors R18 and C7 form a third low-pass filter circuit to further filter out power frequency interference and circuit noise.

[0063] With the above circuit setup, the circuit of this utility model can extract the effective part of the output signal of the tunnel magnetoresistive sensor 6, which facilitates the subsequent use of instruments to confirm the output result of the tunnel magnetoresistive sensor and realizes the accurate calculation of the components of pipeline stress in the X, Y and Z directions.

[0064] Example 2

[0065] Based on Embodiment 1 of this utility model, such as Figure 13 As shown, three single-axis tunnel magnetoresistive sensors are arranged along two planes to form a three-dimensional spatial magnetic field detection system. Figure 13The device includes a first magnetoresistive sensor 20, a second magnetoresistive sensor 21, a third magnetoresistive sensor 22, a first plane 23, and a second plane 24. The first plane 23 and the second plane 24 are perpendicular to each other. The first magnetoresistive sensor 20 is disposed on the first plane 23 and perpendicular to the intersection line of the first plane 23 and the second plane 24. The second magnetoresistive sensor 21 is disposed on the second plane 24 and perpendicular to the intersection line of the first plane 23 and the second plane 24. The third magnetoresistive sensor 22 is disposed on the first plane 23 and perpendicular to the first magnetoresistive sensor 20. The first plane 23 and the second plane 24 are typically circuit board structures, connected by soldering or connectors, and arranged with a circuit designed based on Embodiment 1. The X-axis tunnel magnetoresistive sensor detection circuit 13, the Y-axis tunnel magnetoresistive sensor detection circuit 14, and the Z-axis tunnel magnetoresistive sensor detection circuit 15 are respectively connected to the first magnetoresistive sensor 20, the second magnetoresistive sensor 21, and the third magnetoresistive sensor 22. This constitutes a triaxial stress detection device for pipelines based on tunnel magnetoresistive technology according to this utility model.

[0066] Example 3

[0067] Based on Example 2, such as Figure 14 As shown, by deploying multiple detection probes 30 based on the pipeline triaxial stress detection device of Embodiment 2, and circumferentially arranging them around the sidewall of the pipeline stress detector 31, all-round detection of pipeline internal stress can be achieved.

[0068] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit, characterized in that, The tunneling magnetoresistance sensor detection circuit (13), the tunneling magnetoresistance sensor detection circuit (14) and the tunneling magnetoresistance sensor detection circuit (15) all comprise a phase-sensitive detection circuit (11), and the output of the reference signal generation circuit (5) is connected to each phase-sensitive detection circuit (11) respectively.

2. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 1, wherein, The output of the excitation signal generation circuit (4) is a sinusoidal excitation signal, and the reference signal generation circuit (5) converts the sinusoidal excitation signal into a reverse signal of the same frequency as the sinusoidal excitation signal and outputs it.

3. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 1, wherein, The phase-sensitive detection circuit (11) comprises a multiplier (9) and a second low-pass filter circuit (10) connected in sequence, one input end of the multiplier (9) is connected to the reference signal generation circuit (5), the other input end is connected to the excitation signal generation circuit (4) through a pre-circuit, and the output end of the second low-pass filter circuit (10) is connected to a post-circuit.

4. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 3, wherein, The pre-circuit comprises a tunneling magnetoresistance sensor (6), an instrument amplifier amplification circuit (7) and a second high-pass filter circuit (8) connected in sequence, the input end of the tunneling magnetoresistance sensor (6) is connected to the excitation signal generation circuit (4), and the output end of the second high-pass filter circuit (8) is connected to the multiplier (9).

5. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 4, wherein, The multiplier (9) is a four-quadrant analog multiplier, the second low-pass filter circuit (10) is composed of two first-order RC cascades, the input of the multiplier (9) is the output signal of the second high-pass filter circuit (8) and the reference signal of the reference signal generation circuit (5), and the output is sum frequency signal and difference frequency signal, and the second low-pass filter circuit (10) filters out the sum frequency signal and retains the difference frequency signal as the output signal of the phase-sensitive detection circuit (11).

6. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 4, wherein, The tunneling magnetoresistance sensor (6) comprises a first tunneling magnetoresistance element, a second tunneling magnetoresistance element, a third tunneling magnetoresistance element and a fourth tunneling magnetoresistance element, the first tunneling magnetoresistance element and the second tunneling magnetoresistance element are connected in series as a first circuit, the third tunneling magnetoresistance element and the fourth tunneling magnetoresistance element are connected in series as a second circuit, the first circuit and the second circuit are connected in parallel to obtain two parallel connection points, the tunneling magnetoresistance sensor (6) comprises an input end and two output ends, the input end is connected to the excitation signal generation circuit (4), and the two output ends are connected to the two parallel connection points respectively.

7. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 6, wherein, The instrument amplifier amplification circuit (7) comprises a first pin, a second pin, a third pin, a fourth pin and an output end, an output end signal of the tunnel magnetoresistance sensor (6) is input to the first pin, another output end signal of the tunnel magnetoresistance sensor (6) is input to the fourth pin, the second pin and the third pin are connected through a gain resistor, and the output end of the instrument amplifier amplification circuit (7) is connected to the second high-pass filter circuit (8).

8. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 3, wherein, The post-circuit comprises an in-phase amplification circuit (12).

9. A tunneling magnetoresistive based pipe triaxial stress internal detection circuit according to claim 8, wherein, The in-phase amplification circuit (12) comprises an amplification circuit and a third low-pass filter circuit, and an input signal of the in-phase amplification circuit (12) is amplified through the amplification circuit and then output through the third low-pass filter circuit.

10. A tunneling magnetoresistive based pipe triaxial stress internal inspection device, characterized by, The X-axis tunnel magnetoresistance sensor detection circuit (13), the Y-axis tunnel magnetoresistance sensor detection circuit (14) and the Z-axis tunnel magnetoresistance sensor detection circuit (15) are connected to the first magnetoresistance sensor (20), the second magnetoresistance sensor (21) and the third magnetoresistance sensor (22) respectively.

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