Magnetoelectric vibration sensor in-situ self-calibration system and method based on improved impedance

Abstract

The invention discloses a magnetoelectric vibration sensor in-situ self-calibration system and method based on improved impedance. The system comprises a magnetoelectric vibration sensor composed of an inertia mass block, a permanent magnet, a spring, a damper, a sensing coil and a shell. The device is characterized in that the sensing coil is mechanically connected with a calibration coil, the calibration coil is connected with an impedance circuit, the impedance circuit is connected with a driving circuit, and the driving circuit is sequentially connected with a signal generator, a voltage collector and a computer. According to the invention, the calibration coil is additionally arranged in the magnetoelectric vibration sensor, and the calibration of the response characteristics of the sensor can be realized at the original installation position without an additional standard sensor. The impedance circuit is additionally arranged in the magnetoelectric vibration sensor, inductive reactance of the calibration coil can be effectively restrained, and the accuracy of in-situ self-calibration in high-frequency signals is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor testing, and particularly relates to an in-situ self-calibration system and method for a magnetoelectric vibration sensor based on improved impedance. Background Art

[0002] A magnetoelectric vibration sensor consists of a mechanical vibration pickup system and an electromagnetic induction system. During monitoring, relative movement occurs between the coil and the permanent magnet inside the sensor, thereby generating an induced electromotive force proportional to the relative movement speed. Magnetoelectric vibration sensors can measure low-frequency or ultra-low-frequency vibration signals, and due to their advantages such as high signal-to-noise ratio, good stability, and large dynamic range, they are widely used in fields such as seismic observation and ground pulsation observation, structural health monitoring, energy and mining engineering, etc. During long-term service, affected by factors such as temperature, installation angle, and aging, the response characteristic curve of the magnetoelectric vibration sensor will deviate significantly from the response characteristic at the time of factory shipment, resulting in a significant decrease in measurement accuracy. At this time, the sensor needs to be recalibrated. The calibration methods for magnetoelectric vibration sensors are divided into laboratory calibration and in-situ calibration.

[0003] In practical engineering, many magnetoelectric vibration sensors need to ensure long-term online monitoring, making it difficult to disassemble them for laboratory calibration, and the laboratory calibration results may not match the on-site working conditions, so the calibration results are not applicable to the actual working conditions. In-situ calibration means that the sensor is calibrated in the existing working environment. Common in-situ calibration methods include the sensor reciprocity method and the built-in coil self-calibration method.

[0004] The sensor reciprocity method uses a calibrated standard and same-type sensor and an external excitation circuit to calibrate the sensor to be calibrated. This method requires an additional sensor and is cumbersome to operate.

[0005] The built-in coil self-calibration method adds a calibration coil inside the sensor, and an external excitation signal is input to the calibration coil. The calibration coil becomes a vibration source under the action of the Ampere force, and then according to the characteristic relationship between the output response and the input excitation signal, the calibration of the sensor response characteristic is realized. However, when the frequency of the input excitation signal is high, the inductive reactance between the calibration coil and the sensing coil also increases, which will significantly affect the accuracy of in-situ self-calibration at this time. Summary of the Invention

[0006] In view of the above existing problems, the present invention proposes an in-situ self-calibration system and method for a magnetoelectric vibration sensor based on improved impedance, which can reduce the interference of inductive reactance in the magnetoelectric vibration sensor and achieve high-accuracy calibration in the full frequency band of low, medium, and high frequencies.

[0007] The above object is achieved by the following technical solutions:

[0008] The present invention first provides an in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance, comprising a magnetoelectric vibration sensor composed of an inertial mass block, a permanent magnet, a spring, a damper, a sensing coil and a shell; the sensing coil is mechanically connected to a calibration coil, the calibration coil is connected to an impedance circuit, the impedance circuit is connected to a drive circuit, and the drive circuit is sequentially connected to a signal generator, a voltage collector and a computer.

[0009] Furthermore, the calibration coil and the sensor coil adopt an integrated structure.

[0010] Furthermore, the winding directions of the calibration coil and the sensing coil are completely opposite.

[0011] Furthermore, the impedance circuit is composed of a pure resistor R.

[0012] Another object of the present invention is to provide a method for in-situ self-calibration of a magnetoelectric vibration sensor using the above-mentioned in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance, the method comprising the following steps:

[0013] S1. The magnetoelectric vibration sensor is fixed in the original installation position without external vibration, the magnetoelectric vibration sensor, the drive circuit, and the signal generator are connected in series, the signal generator generates a sinusoidal signal, and the drive circuit generates a corresponding sinusoidal excitation voltage e;

[0014] S2. The sinusoidal excitation voltage e acts on the pure resistor R and the calibration coil. The calibration coil undergoes periodic motion under the action of the Ampere force F, and its displacement is x. The relationship between the Ampere force F and x is:

[0015]

[0016] Wherein, k is the spring stiffness of the magnetoelectric vibration sensor, b is the sensor damping of the magnetoelectric vibration sensor, and m is the inertial block mass of the magnetoelectric vibration sensor;

[0017] S3. The sensor coil is driven by the calibration coil and moves periodically under the action of the Ampere force F. Its displacement is also x. During the movement of the sensor coil, it cuts the magnetic field lines of force to generate an output voltage signal e. 1 ; Define coil displacement x and output voltage signal e 1 The transfer function relationship between them is G 1 (s):

[0018]

[0019] In the formula, s is a complex variable used to describe the dynamic characteristics of the system;

[0020] S4. The voltage signal of the pure resistor R is measured by the voltage collector as U. According to the sensor circuit structure, the relationship between the voltage U and the calibration coil Ampere force F is:

[0021]

[0022] Combining equation (1) with equation (3), we can get the transfer function relationship between displacement x and voltage U as follows:

[0023]

[0024] Where G is the electromechanical coupling coefficient of the calibration coil;

[0025] S5. Calibrate coil inductance L s It includes the self-inductance of the calibration coil and the mutual inductance between the calibration coil and the sensing coil. Its magnitude depends on the frequency of the sinusoidal excitation voltage e. Considering the inductance L of the calibration coil s The transfer function relationship between the sinusoidal excitation voltage e and the calibration coil Ampere force F is:

[0026]

[0027] In the formula, R s To calibrate the coil resistance;

[0028] Combining equation (1) with equation (5), the transfer function relationship between coil displacement x and e is obtained as follows:

[0029]

[0030] S6. Combining equation (2) with equation (4), we can get voltage U and output voltage signal e 1 Time transfer function Combining equation (2) with equation (6), we can get the input voltage signal e and the output voltage signal e 1 Time transfer function Specifically:

[0031]

[0032] S7. The amplitude and phase of the fixed input sinusoidal voltage signal e remain unchanged. The frequency of the output signal is set by the signal generator. The frequency f of the voltage U also changes accordingly. The voltage signal U of the resistor R and the voltage signal e of the sensor coil are recorded by the voltage collector. 1 ;

[0033] S8. The voltage collector uploads the two-way voltage data to the computer, and the computer analyzes and obtains the amplitude U of the voltage signal U max And the voltage signal e 1 The amplitude e 1max , Umax With e 1max The ratio of is the self-calibration sensitivity at frequency f;

[0034] S9. Repeat steps S7 and S8, adjust the signal generator to output sinusoidal signals of different frequencies, measure the self-calibration response sensitivity of the magnetoelectric vibration sensor when the frequency f has different values, and finally obtain the self-calibration sensitivity curve of the magnetoelectric vibration sensor.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention adds a calibration coil inside the magnetoelectric vibration sensor, and can achieve calibration of the sensor response characteristics at the original installation position without the need for an additional standard sensor.

[0037] 2. Adding an impedance circuit inside the magnetoelectric vibration sensor can effectively suppress the inductive reactance of the calibration coil and improve the accuracy of in-situ self-calibration for high-frequency signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the structure of a conventional magnetoelectric vibration sensor (without calibration coil);

[0039] Figure 2 It is a schematic diagram of the structure of a magnetoelectric vibration sensor (with a calibration coil);

[0040] Figure 3 It is a schematic diagram of the structure of the magnetoelectric vibration sensor (with calibration coil and impedance circuit) in the present invention;

[0041] Figure 4 It is a structural schematic diagram of the in-situ self-calibration method of the magnetoelectric vibration sensor in the present invention;

[0042] Figure 5 It is a flow chart of the in-situ self-calibration method of the magnetoelectric vibration sensor of the present invention;

[0043] Description of reference numerals in the figures:

[0044] 1. Inertial mass block; 2. Permanent magnet; 3. Spring; 4. Damping; 5. Sensor coil; 6. Calibration coil; 7. Impedance circuit. DETAILED DESCRIPTION

[0045] Example 1

[0046] like Figure 1As shown, a conventional magnetoelectric vibration sensor consists of an inertial mass 1, a permanent magnet 2, a spring 3, a damper 4, a sensing coil 5, and a housing. During design, the natural frequency of the system is made much lower than the vibration frequency of the object to be measured. At this time, when the object to be measured vibrates, the permanent magnet remains stationary in space, and the movement of the permanent magnet relative to the coil is the movement of the object to be measured. Its working principle is that when the permanent magnet moves up and down, an induced electromotive force is generated in the coil. If the coil is in an open circuit state, the output voltage is proportional to the relative velocity of the permanent magnet in the coil (i.e., the velocity of the object to be measured), and the sensor outputs a voltage quantity proportional to the velocity of the object to be measured.

[0047] As Figure 2 shown, the in-situ self-calibration system of the magnetoelectric vibration sensor based on improved impedance of the present invention is to mechanically connect a calibration coil 6 to the sensing coil 5 of the conventional magnetoelectric vibration sensor, as Figure 3 shown, the calibration coil 6 described in the present invention is connected to an impedance circuit 7, the impedance circuit is connected to a drive circuit, and the drive circuit is sequentially connected to a signal generator, a voltage collector, and a computer.

[0048] The winding directions of the calibration coil and the sensing coil of the present invention are completely opposite, which can reduce the inductive reactance of the calibration coil to the sensing coil. The present invention additionally connects an impedance circuit in series on the calibration coil. By measuring the voltage U on the pure resistor R with a voltmeter and using the voltage U instead of the excitation voltage e as the input signal, the inductive reactance of the calibration coil can be ignored, making the transfer function of the sensor input signal and output signal close to the laboratory calibration method, and effectively improving the accuracy of in-situ self-calibration.

[0049] Embodiment 2

[0050] See Figure 4 , the usage method of the in-situ self-calibration system of the magnetoelectric vibration sensor based on improved impedance in Embodiment 1 includes the following steps:

[0051] S1. Fix the magnetoelectric vibration sensor at the original installation position without external vibration, connect the magnetoelectric vibration sensor, the drive circuit, and the signal generator in series in sequence. The signal generator generates a sine signal, and then the drive circuit generates a corresponding sine excitation voltage e;

[0052] S2. The sine excitation voltage e acts on the pure resistor R and the calibration coil. The calibration coil undergoes periodic motion under the action of the Ampere force F, and its displacement is x. Then the relationship between the Ampere force F and x is:

[0053]

[0054] In the formula, k is the spring stiffness of the magnetoelectric vibration sensor, b is the sensor damping of the magnetoelectric vibration sensor, and m is the mass of the inertial block of the magnetoelectric vibration sensor;

[0055] S3. The calibration coil and the sensing coil adopt an integrated structure. The calibration coil becomes a vibration source under the action of the Ampere force. Then, the sensing coil is driven by the calibration coil and performs periodic motion under the action of the Ampere force F, and its displacement is also x. The sensing coil cuts the magnetic induction lines of the magnetic field during the motion process to generate an output voltage signal e 1 ; Define the transfer function relationship between the coil displacement x and the output voltage signal e 1 as G 1 (s):

[0056]

[0057] In the formula, s is a complex variable used to describe the dynamic characteristics of the system;

[0058] S4. The voltage signal of the pure resistor R is measured by a voltage collector as U. According to the sensor circuit structure, the relationship between the voltage U and the Ampere force F of the calibration coil is:

[0059]

[0060] Combining formula (1) and formula (3), the transfer function relationship between the displacement x and the voltage U can be obtained as:

[0061]

[0062] In the formula, G is the electromechanical coupling coefficient of the calibration coil;

[0063] S5. The inductive reactance L of the calibration coil s includes the self-inductive reactance of the calibration coil and the mutual inductive reactance with the sensing coil. Its magnitude depends on the frequency of the sinusoidal excitation voltage e. Considering the existence of the inductive reactance L of the calibration coil s the transfer function relationship between the sinusoidal excitation voltage e and the Ampere force F of the calibration coil is:

[0064]

[0065] In the formula, R s is the resistance of the calibration coil;

[0066] Combining formula (1) and formula (5), the transfer function relationship between the coil displacement x and e is obtained as:

[0067]

[0068] S6. Combining formula (2) and formula (4), the transfer function between the voltage U and the output voltage signal e 1 can be obtained. Combining formula (2) and formula (6), the transfer function between the input voltage signal e and the output voltage signal e can be obtained. Combining formula (2) and formula (6), the transfer function between the input voltage signal e and the output voltage signal e 1 can be obtained. Specifically:

[0069]

[0070] Obviously, the transfer function in Equation (7) has a significantly lower order and is closer to the laboratory calibration method. Therefore, using the voltage U as the input signal for self-calibration results in higher accuracy.

[0071] S7. Keep the amplitude and phase of the input sinusoidal voltage signal e unchanged. Set the frequency of the output signal through the signal generator. The frequency f of the corresponding voltage U also changes accordingly. Therefore, directly collect the voltage signal U of the pure resistor R in the circuit and the output voltage signal e of the sensing coil using a voltage collector 1 ;

[0072] S8. The voltage collector uploads the two-channel voltage data to the computer. The computer analyzes to obtain the amplitude U of the voltage signal U max and the amplitude e of the voltage signal e 1 . The ratio of U 1max to e max is the self-calibration sensitivity at the current frequency f; 1max

[0073] S9. Repeat steps S7 and S8. Adjust the signal generator to output sinusoidal signals of different frequencies. The frequency f of the corresponding voltage U also changes accordingly. The self-calibration response sensitivity of the magnetoelectric vibration sensor can be measured at different values of different frequencies f. Finally, obtain the self-calibration sensitivity curve of the magnetoelectric vibration sensor.​

Claims

1. An in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance, comprising a magnetoelectric vibration sensor composed of an inertial mass block, a permanent magnet, a spring, a damper, a sensor coil and a housing; characterized in that: The sensing coil is mechanically connected to a calibration coil, the calibration coil is connected to an impedance circuit, the impedance circuit is connected to a drive circuit, and the drive circuit is sequentially connected to a signal generator, a voltage collector and a computer.

2. The in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance according to claim 1, characterized in that: The calibration coil and the sensing coil adopt an integrated structure.

3. The in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance according to claim 1, characterized in that: The winding directions of the calibration coil and the sensing coil are completely opposite.

4. The in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance according to claim 1, characterized in that: The impedance circuit is composed of a pure resistor R.

5. A method for in-situ self-calibration of a magnetoelectric vibration sensor using the in-situ self-calibration system of a magnetoelectric vibration sensor based on improved impedance as claimed in any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1. The magnetoelectric vibration sensor is fixed in the original installation position without external vibration, the magnetoelectric vibration sensor, the drive circuit, and the signal generator are connected in series, the signal generator generates a sinusoidal signal, and the drive circuit generates a corresponding sinusoidal excitation voltage e; S2. The sinusoidal excitation voltage e acts on the pure resistor R and the calibration coil. The calibration coil undergoes periodic motion under the action of the Ampere force F, and its displacement is x. The relationship between the Ampere force F and x is: Wherein, k is the spring stiffness of the magnetoelectric vibration sensor, b is the sensor damping of the magnetoelectric vibration sensor, and m is the inertial block mass of the magnetoelectric vibration sensor; S3. The sensor coil is driven by the calibration coil to move periodically under the action of the Ampere force F, and its displacement is also x. During the movement of the sensor coil, it cuts the magnetic field lines of force to generate an output voltage signal e1; the transfer function relationship between the coil displacement x and the output voltage signal e1 is defined as G1(s): In the formula, s is a complex variable used to describe the dynamic characteristics of the system; S4. The voltage signal of the pure resistor R is measured by the voltage collector as U. According to the sensor circuit structure, the relationship between the voltage U and the calibration coil Ampere force F is: Combining equation (1) with equation (3), we can get the transfer function relationship between displacement x and voltage U as follows: Where G is the electromechanical coupling coefficient of the calibration coil; S5. Calibrate coil inductance L s It includes the self-inductance of the calibration coil and the mutual inductance between the calibration coil and the sensing coil. Its magnitude depends on the frequency of the sinusoidal excitation voltage e. Considering the calibration coil inductance L s The transfer function relationship between the sinusoidal excitation voltage e and the calibration coil Ampere force F is: In the formula, R s To calibrate the coil resistance; Combining equation (1) with equation (5), the transfer function relationship between coil displacement x and e is obtained as follows: S6. Combining equation (2) with equation (4), we can get the transfer function between voltage U and output voltage signal e1: Combining equation (2) with equation (6), we can obtain the transfer function between the input voltage signal e and the output voltage signal e1: Specifically: S7. The amplitude and phase of the input sinusoidal voltage signal e are fixed, and the frequency of the output signal is set by the signal generator. The frequency f of the voltage U also changes accordingly. The voltage signal U of the pure resistor R and the voltage signal e1 of the sensor coil are recorded by the voltage collector; S8. The voltage collector uploads the two-way voltage data to the computer, which analyzes the voltage signal U to obtain the amplitude U max And the amplitude e of the voltage signal e1 1max , U max With e 1max The ratio of is the self-calibration sensitivity at frequency f; S9. Repeat steps S7 and S8, adjust the signal generator to output sinusoidal signals of different frequencies, measure the self-calibration response sensitivity of the magnetoelectric vibration sensor when the frequency f has different values, and finally obtain the self-calibration sensitivity curve of the magnetoelectric vibration sensor.

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