Temperature compensation method and system for eddy current displacement sensor

Abstract

The invention relates to the technical field of eddy current sensor processing, and discloses a temperature compensation method and system for an eddy current displacement sensor. According to the method, temperature change is detected through thermosensitive components bonded on a sensor probe and a converter control panel, a fitting curve is obtained through a test, and real-time compensation is carried out through software in the actual use process. The temperature compensation method does not influence the original working characteristics of the sensor and does not occupy the space; compensation through software is simple and high in flexibility, and the method can be widely applied to temperature compensation of the eddy current displacement sensor.

Description

Technical Field

[0001] The present invention relates to the field of eddy current sensor processing technology, and in particular to a temperature compensation method and system for an eddy current displacement sensor. Background Art

[0002] The eddy current displacement sensor consists of a probe coil, an extension cable, a converter control board and a measured object. As a relative non-contact sensor, the eddy current displacement sensor generates a high-frequency oscillating current from the oscillation circuit of the converter control board that flows into the internal coil of the sensor probe, and an alternating magnetic field is generated in the coil. When the metal target to be measured is close to this alternating magnetic field, an induced current is generated on the surface of the metal target. At the same time, the induced current also generates an alternating magnetic field in the opposite direction of the internal coil of the probe. The two magnetic fields are superimposed and will change the impedance of the coil. The impedance change of the probe coil is detected by the modulation and demodulation circuit of the converter control board, and the impedance change is transformed and amplified by the amplifier circuit to output a voltage signal proportional to the distance between the probe and the surface of the conductor to be measured. However, in actual use, the resistivity of the material selected for the probe coil changes with temperature, which causes the static impedance of the coil to be greatly affected by temperature changes. At the same time, the parameters of the control circuit device of the converter control board will also drift with temperature, which will also cause test deviation of the eddy current sensor. The current compensation measures mainly include: 1. Using precious metals such as palladium silver alloy at the probe to reduce temperature drift. This compensation method increases costs due to the use of precious metals with low temperature drift, and only compensates for the temperature change of the probe coil. It is impossible to compensate for the temperature change of the converter control board. 2. Adding a differential compensation coil. In order to avoid affecting the original working characteristics of the sensor, the position of the compensation coil is mostly far away from the induction coil, which will increase the volume of the sensor coil. It can be seen that in the prior art, there is a problem that it is difficult to effectively compensate for the temperature drift of the eddy current sensor without increasing the volume. Summary of the invention

[0003] The present invention provides a temperature compensation method and system for an eddy current displacement sensor, so as to solve the problem in the prior art that it is difficult to effectively compensate the temperature drift of the eddy current sensor without increasing the volume.

[0004] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0005] In a first aspect, the present invention provides a temperature compensation method for an eddy current displacement sensor, which is applied to the eddy current displacement sensor, wherein the eddy current displacement sensor comprises a sensor probe and a converter control board connected to the sensor probe via a cable, and the method comprises:

[0006] S1: Adding a temperature measuring bridge circuit to the converter control board, bonding a first temperature measuring platinum resistor to the surface of the converter control board, and bonding a second temperature measuring platinum resistor to the inner side of the coil of the sensor probe;

[0007] S2: Connecting the first temperature measuring platinum resistor in series to the temperature measuring bridge circuit;

[0008] S3: setting the environment of the converter control board and the sensor probe according to the setting mode, and outputting the temperature change curve of the sensor probe or the converter control board under the environment;

[0009] S4: Performing temperature compensation based on the curve fitting parameters of the temperature change curve.

[0010] Optionally, the S3 includes:

[0011] S31: Record the temperature characteristic parameters of the eddy current sensor through experiments;

[0012] S32: placing the sensor probe in a constant temperature system, placing the converter control board in a variable temperature system, and measuring the output according to the temperature point along with the temperature change curve of the converter control board;

[0013] S33: placing the converter control board in a constant temperature system, placing the sensor probe in a variable temperature system, and measuring the output according to the temperature point along with the temperature change curve of the sensor probe.

[0014] Optionally, the S31 includes:

[0015] Place the sensor probe and converter control board in a temperature box that can achieve heating, cooling and insulation functions. Turn on the power at room temperature. When the temperature of the sensor probe and the converter control board stabilizes at T1℃ and T2℃, calibrate the displacement L and sensor output V to obtain the displacement and output fitting curve formula, which satisfies the following relationship:

[0016] L = aV + b (1);

[0017] Where a represents the first-order constant of the displacement and output fitting curve, and b represents the zero-order constant of the displacement and output fitting curve.

[0018] Optionally, the S32 includes:

[0019] Place the sensor probe in the incubator, place the converter control board outside the incubator, turn on the power and wait for the converter temperature to stabilize at T2℃, then start the test, set the incubator to N different temperatures in turn, and after the sensor probe temperature stabilizes at each temperature point, record the sensor probe stable temperature and sensor output voltage V in turn, and obtain the fitting curve of the sensor probe's influence on the output voltage with temperature, which satisfies the following relationship:

[0020] V=a 1 T+b 1 ; (2)

[0021] In the formula, a 1 Indicates the linear constant of the fitting curve of the effect of temperature on the output voltage of the sensor probe, b 1 It represents the zero-order constant of the fitting curve of the effect of temperature on the output voltage of the sensor probe, and T represents temperature.

[0022] Optionally, the S33 includes:

[0023] Place the converter control board in the incubator, place the sensor probe outside the incubator, turn on the power and wait for the sensor probe temperature to stabilize at T1℃, then start the test, set the incubator to N different temperatures in turn, and after the converter control board temperature stabilizes at each temperature point, record the converter control board stable temperature and the sensor probe output voltage V in turn, and obtain the converter output voltage fitting curve with temperature, which satisfies the following relationship:

[0024] V=a 2 T+b 2 (3);

[0025] In the formula, a 2 b represents the linear constant of the fitting curve of the converter's influence on the output voltage with temperature, 2 It represents the zero-order constant of the fitting curve of the converter's output voltage affected by temperature, and T represents temperature.

[0026] Optionally, the S4 includes:

[0027] The parameters of the fitting curve of the effect of temperature on the output voltage of the sensor probe and the fitting curve of the effect of temperature on the output voltage of the converter are downloaded into the chip of the converter control board. After each power-on, the real-time temperature T3℃ of the sensor probe is used to compensate the output voltage V1 of the sensor probe at T1℃ through the parameters of the fitting curve of the effect of temperature on the output voltage of the sensor probe.

[0028] Using the real-time temperature T4℃ of the converter control board and the parameters of the fitting curve of the converter's output voltage affected by temperature, V1 is compensated to obtain the converter's output voltage V2 at T2℃;

[0029] Substitute V2 into the displacement and output fitting curve to calculate the distance data of the eddy current displacement sensor under temperature changes in real time.

[0030] Optionally, setting the temperature box to N different temperatures in sequence includes:

[0031] Set the temperature box to -40℃, -20℃, 0℃, 20℃, 40℃, 60℃, and 80℃ in sequence.

[0032] In a second aspect, the present application provides a temperature compensation system for an eddy current displacement sensor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the first aspect when executing the computer program.

[0033] Beneficial effects:

[0034] The present application provides a temperature compensation method for an eddy current displacement sensor, which detects temperature changes by bonding thermistors to the sensor probe and the converter control board, obtains a fitting curve through experiments, and performs real-time compensation through software during actual use. The temperature compensation method does not affect the original working characteristics of the sensor and does not occupy volume; compensation through software is simple and flexible, and can be widely used in temperature compensation of eddy current displacement sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 One of the flow charts of a temperature compensation method of an eddy current displacement sensor according to a preferred embodiment of the present invention;

[0036] Figure 2 This is a second flow chart of a temperature compensation method for an eddy current displacement sensor according to a preferred embodiment of the present invention;

[0037] Figure 3 It is a schematic structural diagram of an eddy current displacement sensor according to a preferred embodiment of the present invention.

[0038] Reference numerals:

[0039] 1. Second temperature measuring platinum resistor; 2. Sensor probe; 3. Cable; 4. Converter control board; 5. First temperature measuring platinum resistor. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The "first level", "second level" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one" or "one" do not indicate quantity restrictions, but indicate the existence of at least one. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0042] See also Figure 1 The present application provides a temperature compensation method for an eddy current displacement sensor, which is applied to the eddy current displacement sensor. The eddy current displacement sensor includes a sensor probe 2 and a converter control board 4 connected to the sensor probe 2 via a cable 3. The method includes:

[0043] S1: Add a temperature measuring bridge circuit on the converter control board 4, and bond a first temperature measuring platinum resistor 5 to the surface of the converter control board 4, and bond a second temperature measuring platinum resistor 1 to the inner side of the coil of the sensor probe 2;

[0044] S2: Connecting the first temperature measuring platinum resistor 5 in series to the temperature measuring bridge circuit;

[0045] S3: setting the environment of the converter control board 4 and the sensor probe 2 according to the setting mode, and outputting the temperature change curve of the sensor probe 2 or the converter control board 4 under the environment;

[0046] S4: Performing temperature compensation based on the curve fitting parameters of the temperature change curve.

[0047] In one example, an eddy current displacement sensor such as Figure 2 As shown, it includes a sensor probe 2 and a converter control board 4 connected to the sensor probe 2 through a cable 3, a temperature measuring bridge is added to the converter control board 4, and a first temperature measuring platinum resistor 5 is bonded to the surface of the converter control board 4, and a second temperature measuring platinum resistor 1 is bonded to the inner side of the coil of the sensor probe 2.

[0048] The temperature compensation method of the eddy current displacement sensor described above detects temperature changes by bonding the thermosensitive components on the sensor probe 2 and the converter control board 4, obtains a fitting curve through experiments, and performs real-time compensation through software during actual use. This temperature compensation method does not affect the original working characteristics of the sensor and does not occupy volume; compensation through software is simple and flexible, and can be widely used in temperature compensation of eddy current displacement sensors.

[0049] Optionally, the S3 includes:

[0050] S31: Record the temperature characteristic parameters of the eddy current sensor through experiments;

[0051] S32: placing the sensor probe 2 in a constant temperature system, placing the converter control board 4 in a variable temperature system, and measuring the output according to the temperature point along the temperature change curve of the converter control board 4;

[0052] S33: placing the converter control board 4 in a constant temperature system, placing the sensor probe 2 in a variable temperature system, and measuring the output according to the temperature point along the temperature change curve of the sensor probe 2.

[0053] Specifically, the S31 includes:

[0054] The sensor probe 2 and the converter control board 4 are placed in a temperature box that can achieve heating, cooling and heat preservation functions. Power on at room temperature. When the temperature of the sensor probe 2 and the converter control board 4 are stable at T1°C and T2°C, the displacement L and the sensor output V are calibrated to obtain the displacement and output fitting curve formula, which satisfies the following relationship:

[0055] L = aV + b (1);

[0056] Where a represents the first-order constant of the displacement and output fitting curve, and b represents the zero-order constant of the displacement and output fitting curve.

[0057] The S32 includes:

[0058] The sensor probe 2 is placed in the incubator, and the converter control board 4 is placed outside the incubator. When the converter temperature is stabilized at T2°C, the test is started. The incubator is set to N different temperatures in turn. After the temperature of the sensor probe 2 is stabilized at each temperature point, the stable temperature of the sensor probe 2 and the sensor output voltage V are recorded in turn. The fitting curve of the effect of the temperature on the output voltage of the sensor probe 2 is obtained, which satisfies the following relationship:

[0059] V=a 1 T+b 1 ; (2)

[0060] In the formula, a 1Indicates the linear constant of the fitting curve of the effect of temperature on the output voltage of sensor probe 2, b 1 It represents the zero-order constant of the fitting curve of the effect of temperature on the output voltage of sensor probe 2, and T represents temperature.

[0061] The S33 includes:

[0062] The converter control board 4 is placed in the incubator, and the sensor probe 2 is placed outside the incubator. When the temperature of the sensor probe 2 is stabilized at T1°C, the test is started. The incubator is set to N different temperatures in turn. After the temperature of the converter control board 4 is stabilized at each temperature point, the stable temperature of the converter control board 4 and the output voltage V of the sensor probe 2 are recorded in turn. The fitting curve of the converter output voltage affected by temperature is obtained, which satisfies the following relationship:

[0063] V=a 2 T+b 2 (3);

[0064] In the formula, a 2 b represents the linear constant of the fitting curve of the converter's influence on the output voltage with temperature, 2 It represents the zero-order constant of the fitting curve of the converter's output voltage affected by temperature, and T represents temperature.

[0065] Furthermore, the parameters of the above formula 2 and formula 3 are downloaded into the chip of the converter control board 4, and each time the power is turned on, the real-time temperature T3°C of the sensor probe 2 is used to compensate the output voltage V1 of the sensor probe 2 at T1°C through the parameters of formula 2;

[0066] Using the real-time temperature T4°C of the converter control board 4 and the parameters of formula 3, V1 is compensated to obtain the output voltage V2 of the converter at T2°C;

[0067] Substitute V2 into Formula 1 to calculate the distance data of the eddy current displacement sensor under temperature changes in real time. This distance data is the compensation result, that is, the true value of the actual detection distance.

[0068] In a specific implementation, the step of sequentially setting the temperature box to N different temperatures includes:

[0069] The temperature box is set to -40°C, -20°C, 0°C, 20°C, 40°C, 60°C, and 80°C in sequence (the settings here are only for example, and only need to cover the actual use needs. The more points in principle, the more accurate it is). This is only an example and is not limited. In other feasible implementations, the set temperature can also be appropriately adjusted.

[0070] The present application provides a temperature compensation system for an eddy current displacement sensor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the first aspect when executing the computer program.

[0071] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A temperature compensation method for an eddy current displacement sensor, applied to the eddy current displacement sensor, wherein the eddy current displacement sensor comprises a sensor probe and a converter control board connected to the sensor probe via a cable, characterized in that: The method comprises: S1: Adding a temperature measuring bridge circuit to the converter control board, bonding a first temperature measuring platinum resistor to the surface of the converter control board, and bonding a second temperature measuring platinum resistor to the inner side of the coil of the sensor probe; S2: Connecting the first temperature measuring platinum resistor in series to the temperature measuring bridge circuit; S3: setting the environment of the converter control board and the sensor probe according to the setting mode, and outputting the temperature change curve of the sensor probe or the converter control board under the environment; S4: Performing temperature compensation based on the curve fitting parameters of the temperature change curve.

2. The temperature compensation method of the eddy current displacement sensor according to claim 1, characterized in that: The S3 includes: S31: Record the temperature characteristic parameters of the eddy current sensor through experiments; S32: placing the sensor probe in a constant temperature system, placing the converter control board in a variable temperature system, and measuring the output according to the temperature point along with the temperature change curve of the converter control board; S33: placing the converter control board in a constant temperature system, placing the sensor probe in a variable temperature system, and measuring the output according to the temperature point along with the temperature change curve of the sensor probe.

3. The temperature compensation method of the eddy current displacement sensor according to claim 2, characterized in that: The S31 includes: Place the sensor probe and converter control board in a temperature box that can achieve heating, cooling and insulation functions. Turn on the power at room temperature. When the temperature of the sensor probe and the converter control board stabilizes at T1℃ and T2℃, calibrate the displacement L and sensor output V to obtain the displacement and output fitting curve formula, which satisfies the following relationship: L = aV + b (1); Where a represents the first-order constant of the displacement and output fitting curve, and b represents the zero-order constant of the displacement and output fitting curve.

4. The temperature compensation method of the eddy current displacement sensor according to claim 3, characterized in that: The S32 includes: Place the sensor probe in the incubator, place the converter control board outside the incubator, turn on the power and wait for the converter temperature to stabilize at T2℃, then start the test, set the incubator to N different temperatures in turn, and after the sensor probe temperature stabilizes at each temperature point, record the sensor probe stable temperature and sensor output voltage V in turn, and obtain the fitting curve of the sensor probe's influence on the output voltage with temperature, which satisfies the following relationship: V=a1T+b1;(2) Wherein, a1 represents the first-order constant of the fitting curve of the influence of temperature on the output voltage of the sensor probe, b1 represents the zero-order constant of the fitting curve of the influence of temperature on the output voltage of the sensor probe, and T represents temperature.

5. The temperature compensation method of the eddy current displacement sensor according to claim 4, characterized in that: The S33 includes: Place the converter control board in the incubator, place the sensor probe outside the incubator, turn on the power and wait for the sensor probe temperature to stabilize at T1℃, then start the test, set the incubator to N different temperatures in turn, and after the converter control board temperature stabilizes at each temperature point, record the converter control board stable temperature and the sensor probe output voltage V in turn, and obtain the converter output voltage fitting curve with temperature, which satisfies the following relationship: V = a2T + b2 (3); Wherein, a2 represents the first-order constant of the fitting curve of the converter's influence on the output voltage as the temperature changes, b2 represents the zero-order constant of the fitting curve of the converter's influence on the output voltage as the temperature changes, and T represents temperature.

6. The temperature compensation method of the eddy current displacement sensor according to claim 5, characterized in that: The S4 includes: The parameters of the fitting curve of the effect of temperature on the output voltage of the sensor probe and the fitting curve of the effect of temperature on the output voltage of the converter are downloaded into the chip of the converter control board. After each power-on, the real-time temperature T3℃ of the sensor probe is used to compensate the output voltage V1 of the sensor probe at T1℃ through the parameters of the fitting curve of the effect of temperature on the output voltage of the sensor probe. Using the real-time temperature T4℃ of the converter control board and the parameters of the fitting curve of the converter's output voltage affected by temperature, V1 is compensated to obtain the converter's output voltage V2 at T2℃; Substitute V2 into the displacement and output fitting curve to calculate the distance data of the eddy current displacement sensor under temperature changes in real time.

7. The temperature compensation method for an eddy current displacement sensor according to any one of claims 4 or 5, characterized in that: The step of sequentially setting the temperature box to N different temperatures includes: Set the temperature box to -40℃, -20℃, 0℃, 20℃, 40℃, 60℃, and 80℃ in sequence.

8. A temperature compensation system for an eddy current displacement sensor, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method described in any one of claims 1 to 7 are implemented.

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