Electromagnetic coil induction signal temperature drift error compensation device and compensation method

Abstract

The invention relates to an electromagnetic coil induction signal temperature drift error compensation device and a compensation method. A constant current source, a direct current component output circuit, an alternating current component output circuit and a detection circuit are respectively arranged on a secondary electromagnetic coil and a compensation electromagnetic coil; after a direct current signal is injected, an output signal of a corresponding electromagnetic coil is filtered to separate a direct current component signal and an alternating current component signal, a sampling voltage is detected according to the alternating current component signal, and finally a data processing module carries out secondary induction signal compensation and compensation induction signal compensation respectively. According to the device, a temperature measurement platinum resistor does not need to be additionally arranged in the sensor to compensate the temperature drift of an induction signal of the sensor, so that the complexity of structural composition of the sensor can be reduced, a poor compensation effect caused by medium attenuation and non-uniform medium thermal conductivity in a conduction process of platinum resistor temperature measurement is avoided, and the compensation accuracy is improved.

Description

Technical Field

[0001] This application relates to the field of electromagnetic sensing technology, and particularly to an electromagnetic coil induction signal temperature drift error compensation device and a compensation method. Background Art

[0002] In a measurement system based on the principle of electromagnetic induction, the drift of the resistance of the electromagnetic induction coil itself due to changes in temperature and the surrounding environment is an important cause of measurement system errors. Generally, corresponding compensation measures need to be taken for its temperature drift error to improve the detection accuracy of the measurement system. The traditional temperature compensation method for the induction signal of an electromagnetic sensor is to measure the temperature inside the sensor by additionally installing a temperature-measuring platinum resistance. Since the temperature-measuring platinum resistance has certain conductivity and magnetic permeability and has a certain influence on the weak induction signal of the electromagnetic coil, it cannot be closely connected to the induction coil and needs to maintain a certain distance. This results in a certain time required for temperature conduction between the platinum resistance and the induction coil, with a large delay and a lag in compensation. Moreover, due to the medium attenuation and non-uniform medium thermal conductivity during the conduction process, the temperature measured by the platinum resistance is not the accurate temperature of the coil, which also leads to poor compensation effect and the disadvantage of low compensation accuracy. Summary of the Invention

[0003] Based on this, it is necessary to provide an electromagnetic coil induction signal temperature drift error compensation device and a compensation method that can improve compensation accuracy for the above problems.

[0004] The first aspect of this application provides an electromagnetic coil induction signal temperature drift error compensation device, including a first constant current source, a second constant current source, a first DC component output circuit, a second DC component output circuit, a first AC component output circuit, a second AC component output circuit, a first detection circuit, a second detection circuit, and a data processing module;

[0005] The first constant current source is connected to the secondary electromagnetic coil and outputs a DC signal; the first DC component output circuit is connected to the secondary electromagnetic coil and the data processing module, filters the output signal of the secondary electromagnetic coil, separates the DC component signal generated by the first constant current source, and sends it to the data processing module; the first AC component output circuit is connected to the secondary electromagnetic coil and the first detection circuit, filters the output signal of the secondary electromagnetic coil, separates the AC component signal of the secondary electromagnetic coil, and sends it to the first detection circuit; the first detection circuit is connected to the data processing module, detects the received AC component signal, and outputs a sampling voltage to the data processing module;

[0006] The second constant current source is connected to the compensation electromagnetic coil and outputs a DC signal; the second DC component output circuit is connected to the compensation electromagnetic coil and the data processing module, filters the output signal of the compensation electromagnetic coil, separates the DC component signal generated by the second constant current source, and sends it to the data processing module; the second AC component output circuit is connected to the compensation electromagnetic coil and the second detection circuit, filters the output signal of the compensation electromagnetic coil, separates the AC component signal of the compensation electromagnetic coil, and sends it to the second detection circuit; the second detection circuit is connected to the data processing module, detects the received AC component signal, and outputs a sampled voltage to the data processing module.

[0007] The data processing module performs secondary induction signal compensation according to the DC component signal output by the first DC component output circuit and the sampled voltage output by the first detection circuit; the data processing module performs compensation induction signal compensation according to the DC component signal output by the second DC component output circuit and the sampled voltage output by the second detection circuit.

[0008] In one embodiment, the first DC component output circuit includes a first operational amplifier differential amplification unit and a first operational amplifier low-pass filtering unit. The first operational amplifier differential amplification unit is connected to the secondary electromagnetic coil and the first operational amplifier low-pass filtering unit, and the first operational amplifier low-pass filtering unit is connected to the data processing module.

[0009] The second DC component output circuit includes a second operational amplifier differential amplification unit and a second operational amplifier low-pass filtering unit. The second operational amplifier differential amplification unit is connected to the compensation electromagnetic coil and the second operational amplifier low-pass filtering unit, and the second operational amplifier low-pass filtering unit is connected to the data processing module.

[0010] In one embodiment, the first AC component output circuit includes a capacitor C1, a capacitor C2, a resistor R1, and a resistor R2. The first end of the capacitor C1 is connected to the first end of the secondary electromagnetic coil, the second end of the capacitor C1 is connected to the first end of the resistor R1 and the first detection circuit, the second end of the resistor R1 is grounded, the first end of the capacitor C2 is connected to the second end of the secondary electromagnetic coil, the second end of the capacitor C2 is connected to the first end of the resistor R2 and the first detection circuit, and the second end of the resistor R2 is grounded.

[0011] The second AC component output circuit includes a capacitor C3, a capacitor C4, a resistor R3, and a resistor R4. The first end of the capacitor C3 is connected to the first end of the compensation electromagnetic coil. The second end of the capacitor C3 is connected to the first end of the resistor R3 and the second detection circuit. The second end of the resistor R3 is grounded. The first end of the capacitor C4 is connected to the second end of the compensation electromagnetic coil. The second end of the capacitor C4 is connected to the first end of the resistor R4 and the second detection circuit. The second end of the resistor R4 is grounded.

[0012] In one embodiment, the first detection circuit includes a third operational amplifier differential amplification unit and a first signal detection unit. The third operational amplifier differential amplification unit is connected to the first AC component output circuit and the first signal detection unit. The first signal detection unit is connected to the data processing module;

[0013] The second detection circuit includes a fourth operational amplifier differential amplification unit and a second signal detection unit. The fourth operational amplifier differential amplification unit is connected to the second AC component output circuit and the second signal detection unit. The second signal detection unit is connected to the data processing module.

[0014] In one embodiment, the data processing module calculates the resistance of the secondary electromagnetic coil according to the DC component signal output by the first DC component output circuit, and performs secondary induction signal compensation according to the resistance of the secondary electromagnetic coil, the sampling voltage output by the first detection circuit, and the corresponding compensation parameters; the data processing module calculates the resistance of the compensation electromagnetic coil according to the DC component signal output by the second DC component output circuit, and performs compensation induction signal compensation according to the resistance of the compensation electromagnetic coil, the sampling voltage output by the second detection circuit, and the corresponding compensation parameters.

[0015] In one embodiment, the data processing module performs secondary induction signal compensation according to the resistance of the secondary electromagnetic coil, the sampling voltage output by the first detection circuit, and the corresponding compensation parameters, including:

[0016] Vst = Vs - (a1 * Rs * Rs + b1 * Rs + c1)

[0017] Wherein, Vst is the digital quantity of the compensated secondary induction signal, Vs is the digital quantity of the voltage value of the sampling voltage output by the first detection circuit, Rs is the resistance of the secondary electromagnetic coil, and a1, b1, and c1 are compensation parameters.

[0018] In one embodiment, the data processing module performs compensation induction signal compensation according to the resistance of the compensation electromagnetic coil, the sampling voltage output by the second detection circuit, and the corresponding compensation parameters, including:

[0019] Vct = Vc - (a2 * Rc * Rc + b2 * Rc + c2)

[0020] Among them, Vct is the digital quantity of the compensated induction signal after compensation, Vc is the digital quantity of the voltage value of the sampling voltage output by the second detection circuit, Rc is the resistance of the compensation electromagnetic coil, and a2, b2, and c2 are compensation parameters.

[0021] In one embodiment, the compensation parameters are obtained by polynomial fitting after iterating and cleaning the complete temperature rise and fall data collected through high and low temperature cycle tests on the sensor.

[0022] In one embodiment, the data processing module includes an analog-to-digital converter and a controller. The analog-to-digital converter is connected to the first DC component output circuit, the second DC component output circuit, the first detection circuit, the second detection circuit, and the controller.

[0023] The second aspect of this application provides a method for compensating the temperature drift error of the electromagnetic coil induction signal, which is implemented based on the above-mentioned electromagnetic coil induction signal temperature drift error compensation device. The method includes:

[0024] The first DC component output circuit filters the output signal of the secondary electromagnetic coil, separates the DC component signal generated by the first constant current source, and sends it to the data processing module;

[0025] The first AC component output circuit filters the output signal of the secondary electromagnetic coil, separates the AC component signal of the secondary electromagnetic coil, and sends it to the first detection circuit. The first detection circuit detects the received AC component signal and outputs the sampling voltage to the data processing module;

[0026] The second DC component output circuit filters the output signal of the compensation electromagnetic coil, separates the DC component signal generated by the second constant current source, and sends it to the data processing module;

[0027] The second AC component output circuit filters the output signal of the compensation electromagnetic coil, separates the AC component signal of the compensation electromagnetic coil, and sends it to the second detection circuit. The second detection circuit detects the received AC component signal and outputs the sampling voltage to the data processing module;

[0028] The data processing module compensates the secondary induction signal according to the DC component signal output by the first DC component output circuit and the sampling voltage output by the first detection circuit, and compensates the compensated induction signal according to the DC component signal output by the second DC component output circuit and the sampling voltage output by the second detection circuit.

[0029] The above electromagnetic coil induction signal temperature drift error compensation device and compensation method respectively set a constant current source, a DC component output circuit, an AC component output circuit, and a detection circuit for the secondary electromagnetic coil and the compensation electromagnetic coil. After injecting a DC signal, the output signals of the corresponding electromagnetic coils are filtered to separate the DC component signal and the AC component signal. The sampling voltage is detected based on the AC component signal, and finally, the secondary induction signal compensation and the compensation induction signal compensation are respectively performed by the data processing module. This device no longer requires an additional temperature-measuring platinum resistor in the sensor to compensate for the temperature drift of the induction signal of the sensor, which can reduce the complexity of the sensor structure, avoid the medium attenuation in the conduction process of platinum resistor temperature measurement and the poor compensation effect caused by uneven medium thermal conductivity, and improve the compensation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a schematic structural diagram of an electromagnetic coil induction signal temperature drift error compensation device in an embodiment;

[0031] Figure 2 FIG. is a flowchart of an electromagnetic coil induction signal temperature drift error compensation method in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0034] It can be understood that "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is an electrical signal or data transfer between the connected circuits, modules, units, etc.

[0035] As used herein, the singular forms "a", "an", and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises / comprising", "has / including", etc. specify the presence of the stated features, wholes, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, wholes, operations, components, parts, or combinations thereof.

[0036] In one embodiment, as Figure 1As shown in the figure, an electromagnetic coil induction signal temperature drift error compensation device is provided, which includes a first constant current source 110, a second constant current source 120, a first DC component output circuit 130, a second DC component output circuit 140, a first AC component output circuit 150, a second AC component output circuit 160, a first detection circuit 170, a second detection circuit 180, and a data processing module 190.

[0037] The first constant current source 110 is connected to the secondary electromagnetic coil and outputs a DC signal; the first DC component output circuit 130 is connected to the secondary electromagnetic coil and the data processing module 190, filters the output signal of the secondary electromagnetic coil, separates the DC component signal generated by the first constant current source 110, and sends it to the data processing module 190; the first AC component output circuit 150 is connected to the secondary electromagnetic coil and the first detection circuit 170, filters the output signal of the secondary electromagnetic coil, separates the AC component signal of the secondary electromagnetic coil, and sends it to the first detection circuit 170; the first detection circuit 170 is connected to the data processing module 190, detects the received AC component signal, and outputs a sampled voltage to the data processing module 190.

[0038] The second constant current source 120 is connected to the compensation electromagnetic coil and outputs a DC signal; the second DC component output circuit 140 is connected to the compensation electromagnetic coil and the data processing module 190, filters the output signal of the compensation electromagnetic coil, separates the DC component signal generated by the second constant current source 120, and sends it to the data processing module 190; the second AC component output circuit 160 is connected to the compensation electromagnetic coil and the second detection circuit 180, filters the output signal of the compensation electromagnetic coil, separates the AC component signal of the compensation electromagnetic coil, and sends it to the second detection circuit 180; the second detection circuit 180 is connected to the data processing module 190, detects the received AC component signal, and outputs a sampled voltage to the data processing module 190.

[0039] The data processing module 190 compensates the secondary induction signal according to the DC component signal output by the first DC component output circuit 130 and the sampled voltage output by the first detection circuit 170; the data processing module 190 compensates the compensation induction signal according to the DC component signal output by the second DC component output circuit 140 and the sampled voltage output by the second detection circuit 180.

[0040] Among them, the electromagnetic sensor is provided with a primary electromagnetic coil and a secondary electromagnetic coil. By outputting an excitation signal to the primary electromagnetic coil and then analyzing the induction signal generated by the secondary electromagnetic coil, the liquid level height can be detected. The central axes of the primary electromagnetic coil and the secondary electromagnetic coil can be perpendicular to each other. For example, the central axis of the primary electromagnetic coil can be arranged parallel to the plane of the liquid level to be detected, and the central axis of the secondary electromagnetic coil can be arranged perpendicular to the plane of the liquid level to be detected, which can make the amplitude of the induced electric field on the secondary electromagnetic coil more sensitive to the change of the liquid level, and the liquid level height detection is more accurate. Further, a compensation electromagnetic coil is also provided in the electromagnetic sensor. The electromagnetic sensor collects the output signals of the secondary electromagnetic coil and the compensation electromagnetic coil, and performs zero adjustment and calibration according to the two collected signals.

[0041] If the method of installing a temperature-measuring platinum resistor is used to perform temperature compensation on the induction signals of the secondary electromagnetic coil and the compensation electromagnetic coil, on the one hand, since the temperature-measuring platinum resistor cannot be closely connected to the induction coil and a certain distance needs to be maintained, it takes a certain amount of time for the temperature conduction between the platinum resistor and the induction coil, resulting in a large delay and lag in compensation. Moreover, due to the medium attenuation and uneven medium thermal conductivity during the conduction process, the temperature measured by the platinum resistor is not the accurate temperature of the coil, which also leads to poor compensation effect. On the other hand, since the number of turns and structures of the secondary induction coil and the compensation induction coil are different, and their spatial positions are also different, the change of their resistivity with the temperature of the sensor is actually not synchronous and proportional. It is difficult to ensure the accuracy by using the temperature measured by the same platinum resistor to compensate them simultaneously.

[0042] Based on this, in the present application, a constant current source, a DC component output circuit, an AC component output circuit, and a detection circuit are respectively provided for the secondary electromagnetic coil and the compensation electromagnetic coil. The first constant current source 110 is connected to both ends of the secondary electromagnetic coil and outputs a DC signal I1; the second constant current source 120 is connected to both ends of the compensation electromagnetic coil and outputs a DC signal I2. After injecting the DC signal, the output signal of the corresponding electromagnetic coil is filtered to separate the DC component signal and the AC component signal. The sampling voltage is detected according to the AC component signal, and finally, the secondary induction signal compensation and the compensation induction signal compensation are respectively performed by the data processing module 190. By adding a constant current source and adding relevant circuits for real-time resistance measurement of the secondary electromagnetic coil and the compensation electromagnetic coil, after the resistance Rs of the secondary electromagnetic coil and the resistance Rc of the compensation electromagnetic coil are measured in real time, temperature compensation correction is respectively performed on the final detection output signals corresponding to the secondary and compensation electromagnetic coils of the sensor. Since the resistance value measured in real time changes synchronously with the temperature change of the corresponding coil, the method for compensating and correcting the error caused by the temperature drift of the sensor coil has better real-time performance and accuracy. There is no need to additionally install a temperature-measuring platinum resistor in the sensor to compensate for the temperature drift of the induction signal of the sensor, which can reduce the complexity of the sensor structure composition, avoid the medium attenuation in the conduction process of platinum resistor temperature measurement and the poor compensation effect caused by uneven medium thermal conductivity, and improve the compensation accuracy.

[0043] Among them, the number of secondary electromagnetic coils and compensation electromagnetic coils can both be one or more. When the number of secondary electromagnetic coils and / or compensation electromagnetic coils is multiple, or when the sensor has other electromagnetic coils that need to collect signals, corresponding constant current sources, DC component output circuits, AC component output circuits, and detection circuits can be respectively set for all electromagnetic coils. After injecting a DC signal into the corresponding electromagnetic coil, the DC component signal and the AC component signal are filtered and separated, and finally, the corresponding induction signal compensation is respectively performed by the data processing module 190.

[0044] It can be understood that the specific structures of the set DC component output circuit, AC component output circuit, and detection circuit are not unique. In one embodiment, such as Figure 1As shown, the first DC component output circuit 130 includes a first operational amplifier differential amplification unit 132 and a first operational amplifier low-pass filtering unit 134. The first operational amplifier differential amplification unit 132 is connected to the secondary electromagnetic coil and the first operational amplifier low-pass filtering unit 134, specifically connecting to both ends of the secondary electromagnetic coil. The first operational amplifier low-pass filtering unit 134 is connected to the data processing module 190. The second DC component output circuit 140 includes a second operational amplifier differential amplification unit 142 and a second operational amplifier low-pass filtering unit 144. The second operational amplifier differential amplification unit 142 is connected to the compensation electromagnetic coil and the second operational amplifier low-pass filtering unit 144, specifically connecting to both ends of the compensation electromagnetic coil. The second operational amplifier low-pass filtering unit 144 is connected to the data processing module 190.

[0045] Further, the first AC component output circuit 150 includes a capacitor C1, a capacitor C2, a resistor R1, and a resistor R2. The first end of the capacitor C1 is connected to the first end of the secondary electromagnetic coil. The second end of the capacitor C1 is connected to the first end of the resistor R1 and the first detection circuit 170. The second end of the resistor R1 is grounded. The first end of the capacitor C2 is connected to the second end of the secondary electromagnetic coil. The second end of the capacitor C2 is connected to the first end of the resistor R2 and the first detection circuit 170. The second end of the resistor R2 is grounded. The second AC component output circuit 160 includes a capacitor C3, a capacitor C4, a resistor R3, and a resistor R4. The first end of the capacitor C3 is connected to the first end of the compensation electromagnetic coil. The second end of the capacitor C3 is connected to the first end of the resistor R3 and the second detection circuit 180. The second end of the resistor R3 is grounded. The first end of the capacitor C4 is connected to the second end of the compensation electromagnetic coil. The second end of the capacitor C4 is connected to the first end of the resistor R4 and the second detection circuit 180. The second end of the resistor R4 is grounded.

[0046] In addition, the first detection circuit 170 includes a third operational amplifier differential amplification unit 172 and a first signal detection unit 174. The third operational amplifier differential amplification unit 172 is connected to the first AC component output circuit 150 and the first signal detection unit 174, specifically connecting to the second ends of the capacitors C1 and C3 in the first AC component output circuit 150. The first signal detection unit 174 is connected to the data processing module 190. The second detection circuit 180 includes a fourth operational amplifier differential amplification unit 182 and a second signal detection unit 184. The fourth operational amplifier differential amplification unit 182 is connected to the second AC component output circuit 160 and the second signal detection unit 184, specifically connecting to the second ends of the capacitors C3 and C4 in the second AC component output circuit 160. The second signal detection unit 184 is connected to the data processing module 190.

[0047] After obtaining the relevant data, the data processing module 190 can specifically calculate the resistance Rs of the secondary electromagnetic coil according to the DC component signal output by the first DC component output circuit 130, and perform secondary induction signal compensation according to the resistance Rs of the secondary electromagnetic coil, the sampling voltage output by the first detection circuit 170, and the corresponding compensation parameters; the data processing module 190 also calculates the resistance Rc of the compensation electromagnetic coil according to the DC component signal output by the second DC component output circuit 140, and performs compensation induction signal compensation according to the resistance Rc of the compensation electromagnetic coil, the sampling voltage output by the second detection circuit 180, and the corresponding compensation parameters.

[0048] The specific structure of the data processing module 190 is not unique either. In one embodiment, continue to refer to Figure 1 , the data processing module 190 includes an analog-to-digital converter 192 and a controller 194. The analog-to-digital converter 192 is connected to the first DC component output circuit 130, the second DC component output circuit 140, the first detection circuit 170, the second detection circuit 180, and the controller 194. The analog-to-digital converter 192 is specifically connected to the first operational amplifier low-pass filtering unit 134, the second operational amplifier low-pass filtering unit 144, the first signal detection unit 174, and the second signal detection unit 184. The controller 194 can be a CPU, MCU, FPGA, etc.

[0049] By dividing the signal on the secondary electromagnetic coil into two paths, one path passes through the first operational amplifier differential amplification unit 132 and the first operational amplifier low-pass filtering unit 134 to separate the DC component generated by the first constant current source 110 in the coil signal, obtain the voltage corresponding to the coil resistance, and after being converted by the analog-to-digital converter 192, the digital quantity of the voltage value in the controller 194 is denoted as V1. The current of the first constant current source 110 is set as I1, then the resistance of the secondary electromagnetic coil is Rs = (V1 / I1) * k1, where k1 is a calibration coefficient. The other path passes through a high-pass circuit composed of a capacitor and a resistor (the first AC component output circuit 150) to isolate and filter the DC component generated by the first constant current source 110 on the coil, and separate the AC signal induced by the coil. After being amplified by the third operational amplifier differential amplification unit 172, this AC signal is then subjected to corresponding filtering and detection by the first signal detection unit 174, and the obtained sampling voltage is converted by the analog-to-digital converter 192 to obtain the digital quantity of the voltage value in the controller 194, denoted as Vs.

[0050] Similarly, by splitting the signal on the compensation electromagnetic coil into two paths, one path passes through the second operational amplifier differential amplification unit 142 and the second operational amplifier low-pass filtering unit 144 to isolate the DC component generated by the second constant current source 120 in the coil signal, obtaining the voltage corresponding to the coil resistance. After being converted by the analog-to-digital converter 192, the digital quantity of the voltage value in the controller 194 is denoted as V2. The current of the second constant current source 120 is set as I2, then the resistance of the secondary electromagnetic coil is Rc = (V2 / I2)*k2, where k2 is the calibration coefficient. The other path passes through a high-pass circuit composed of a capacitor and a resistor (the second AC component output circuit 160) to isolate and filter the DC component generated by the second constant current source 120 on the coil, separating the AC signal induced by the coil. This AC signal is amplified by the fourth operational amplifier differential amplification unit 182 and then undergoes corresponding filtering and detection by the second signal detection unit 184. The sampled voltage obtained is converted by the analog-to-digital converter 192, and the digital quantity of the voltage value in the controller 194 is denoted as Vc.

[0051] The filtering and detection method of the induction signal is not unique. The first signal detection unit 174 and the second signal detection unit 184 can be a full-wave rectification circuit composed of operational amplifiers, or a switched phase-sensitive detection circuit composed of an operational amplifier and a controller. The full-wave rectification circuit has the advantage of being insensitive to phase, but is relatively more sensitive to noise. In this embodiment, both the first signal detection unit 174 and the second signal detection unit 184 can adopt a switched phase-sensitive detection circuit. The switched phase-sensitive detection circuit has a more complex structure and is also sensitive to phase changes, but has a strong ability to extract effective signals from noise.

[0052] The controller 194 performs secondary induction signal compensation and compensation induction signal compensation respectively according to the digital quantities converted by the analog-to-digital converter 192. Denote the digital quantity of the compensated secondary induction signal as Vst, and the digital quantity of the compensated compensation induction signal as Vct. The compensation formulas for the secondary signal and the compensation signal are:

[0053] Vst = Vs - (a1*Rs*Rs + b1*Rs + c1)

[0054] Vct = Vc - (a2*Rc*Rc + b2*Rc + c2)

[0055] Among them, Vs is the digital quantity of the voltage value of the sampled voltage output by the first detection circuit 170, Rs is the resistance of the secondary electromagnetic coil, and a1, b1, c1 are compensation parameters. Vc is the digital quantity of the voltage value of the sampled voltage output by the second detection circuit 180, Rc is the resistance of the compensation electromagnetic coil, and a2, b2, c2 are compensation parameters.

[0056] Among them, the compensation parameters are obtained by polynomial fitting after iterating and cleaning the complete temperature rise and fall data collected from the high and low temperature cycle tests of the sensor. Different electromagnetic sensors have different change trends affected by factors such as temperature. Therefore, it is necessary to conduct separate tests on different models of sensors to determine the compensation parameters of the same model of sensors. The compensation parameters a1, b1, c1, a2, b2, c2 are all obtained by fitting and calculating the data collected from the high and low temperature cycle tests of the sensor. After iterating and cleaning the complete temperature rise and fall data collected, polynomial fitting is used to obtain the corresponding relationship between the sampling voltage and the compensated induction signal at different electromagnetic coil resistance values, so as to determine the compensation parameters at different electromagnetic coil resistances and ensure the compensation accuracy. During actual compensation, the values of the compensation parameters a1, b1, c1 are determined according to the resistance of the actual secondary electromagnetic coil, and the values of the compensation parameters a2, b2, c2 are determined according to the resistance of the actual compensation electromagnetic coil, and then the secondary induction signal compensation and the compensation induction signal compensation are carried out.

[0057] In one embodiment, there is also provided a method for compensating the temperature drift error of the electromagnetic coil induction signal, which is implemented based on the above-mentioned device for compensating the temperature drift error of the electromagnetic coil induction signal, as Figure 2 shown, and the method includes:

[0058] Step S110: The first DC component output circuit filters the output signal of the secondary electromagnetic coil, separates the DC component signal generated by the first constant current source, and sends it to the data processing module.

[0059] Step S120: The first AC component output circuit filters the output signal of the secondary electromagnetic coil, separates the AC component signal of the secondary electromagnetic coil, and sends it to the first detection circuit. The first detection circuit detects the received AC component signal and outputs the sampling voltage to the data processing module.

[0060] Step S130: The second DC component output circuit filters the output signal of the compensation electromagnetic coil, separates the DC component signal generated by the second constant current source, and sends it to the data processing module.

[0061] Step S140: The second AC component output circuit filters the output signal of the compensation electromagnetic coil, separates the AC component signal of the compensation electromagnetic coil, and sends it to the second detection circuit. The second detection circuit detects the received AC component signal and outputs the sampling voltage to the data processing module.

[0062] Step S150: The data processing module performs secondary induction signal compensation based on the DC component signal output by the first DC component output circuit and the sampled voltage output by the first detection circuit, and performs compensated induction signal compensation based on the DC component signal output by the second DC component output circuit and the sampled voltage output by the second detection circuit.

[0063] In one embodiment, step S150 includes: The data processing module calculates the resistance of the secondary electromagnetic coil according to the DC component signal output by the first DC component output circuit, and performs secondary induction signal compensation according to the resistance of the secondary electromagnetic coil, the sampled voltage output by the first detection circuit, and the corresponding compensation parameters; The data processing module calculates the resistance of the compensated electromagnetic coil according to the DC component signal output by the second DC component output circuit, and performs compensated induction signal compensation according to the resistance of the compensated electromagnetic coil, the sampled voltage output by the second detection circuit, and the corresponding compensation parameters.

[0064] It can be understood that the specific implementation embodiments of the above electromagnetic coil induction signal temperature drift error compensation method have been explained in detail in the above electromagnetic coil induction signal temperature drift error compensation device, and will not be elaborated here.

[0065] The above electromagnetic coil induction signal temperature drift error compensation device and compensation method have the following advantages:

[0066] 1) There is no need to additionally install a temperature-measuring platinum resistor in the sensor to compensate for the temperature drift of the induction signal of the sensor, which can reduce the complexity of the sensor structure composition and improve the reliability of the sensor and the measurement system.

[0067] 2) Since the change in the measured resistance value of the electromagnetic coil in real time has basically no delay with the change in the coil temperature, the timeliness of compensation is better, and the medium attenuation and non-uniform medium heat conduction in the conduction process of platinum resistance temperature measurement are avoided in principle, resulting in poor compensation effect.

[0068] 3) The real-time resistance values of the secondary and compensated coils can be used to perform real-time compensation on the two coils respectively, which can better ensure accuracy. Moreover, the secondary electromagnetic coil and the compensated electromagnetic coil no longer need to be designed to be very close to ensure the compensation effect to a certain extent, which can greatly increase the flexibility of the electromagnetic sensor coil structure design.

[0069] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0070] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A device for compensating temperature drift error of electromagnetic coil induction signal, characterized in that: It includes a first constant current source, a second constant current source, a first DC component output circuit, a second DC component output circuit, a first AC component output circuit, a second AC component output circuit, a first detection circuit, a second detection circuit and a data processing module; The first constant current source is connected to the secondary electromagnetic coil and outputs a DC signal; the first DC component output circuit is connected to the secondary electromagnetic coil and the data processing module, filters the output signal of the secondary electromagnetic coil, separates the DC component signal generated by the first constant current source and sends it to the data processing module; the first AC component output circuit is connected to the secondary electromagnetic coil and the first detection circuit, filters the output signal of the secondary electromagnetic coil, separates the AC component signal of the secondary electromagnetic coil and sends it to the first detection circuit; the first detection circuit is connected to the data processing module, detects the received AC component signal and outputs a sampling voltage to the data processing module; The second constant current source is connected to the compensation electromagnetic coil and outputs a DC signal; the second DC component output circuit is connected to the compensation electromagnetic coil and the data processing module, filters the output signal of the compensation electromagnetic coil, separates the DC component signal generated by the second constant current source and sends it to the data processing module; the second AC component output circuit is connected to the compensation electromagnetic coil and the second detection circuit, filters the output signal of the compensation electromagnetic coil, separates the AC component signal of the compensation electromagnetic coil and sends it to the second detection circuit; the second detection circuit is connected to the data processing module, detects the received AC component signal and outputs a sampling voltage to the data processing module; The data processing module performs secondary induction signal compensation according to the DC component signal output by the first DC component output circuit and the sampling voltage output by the first detection circuit; the data processing module performs compensation induction signal compensation according to the DC component signal output by the second DC component output circuit and the sampling voltage output by the second detection circuit.

2. The device according to claim 1, characterized in that The first DC component output circuit includes a first operational amplifier differential amplifier unit and a first operational amplifier low-pass filter unit, the first operational amplifier differential amplifier unit is connected to the secondary electromagnetic coil and the first operational amplifier low-pass filter unit, and the first operational amplifier low-pass filter unit is connected to the data processing module; The second DC component output circuit includes a second operational amplifier differential amplifier unit and a second operational amplifier low-pass filter unit, the second operational amplifier differential amplifier unit is connected to the compensation electromagnetic coil and the second operational amplifier low-pass filter unit, and the second operational amplifier low-pass filter unit is connected to the data processing module.

3. The device according to claim 1, characterized in that The first AC component output circuit comprises a capacitor C1, a capacitor C2, a resistor R1 and a resistor R2, a first end of the capacitor C1 is connected to a first end of the secondary electromagnetic coil, a second end of the capacitor C1 is connected to a first end of the resistor R1 and the first detection circuit, a second end of the resistor R1 is grounded, a first end of the capacitor C2 is connected to a second end of the secondary electromagnetic coil, a second end of the capacitor C2 is connected to a first end of the resistor R2 and the first detection circuit, and a second end of the resistor R2 is grounded; The second AC component output circuit includes a capacitor C3, a capacitor C4, a resistor R3 and a resistor R4, the first end of the capacitor C3 is connected to the first end of the compensation electromagnetic coil, the second end of the capacitor C3 is connected to the first end of the resistor R3 and the second detection circuit, the second end of the resistor R3 is grounded, the first end of the capacitor C4 is connected to the second end of the compensation electromagnetic coil, the second end of the capacitor C4 is connected to the first end of the resistor R4 and the second detection circuit, and the second end of the resistor R4 is grounded.

4. The device according to claim 1, characterized in that The first detection circuit includes a third operational amplifier differential amplification unit and a first signal detection unit, the third operational amplifier differential amplification unit is connected to the first AC component output circuit and the first signal detection unit, and the first signal detection unit is connected to the data processing module; The second detection circuit includes a fourth operational amplifier differential amplification unit and a second signal detection unit, the fourth operational amplifier differential amplification unit is connected to the second AC component output circuit and the second signal detection unit, and the second signal detection unit is connected to the data processing module.

5. The device according to claim 1, characterized in that The data processing module calculates the resistance of the secondary electromagnetic coil based on the DC component signal output by the first DC component output circuit, and performs secondary induction signal compensation based on the resistance of the secondary electromagnetic coil, the sampling voltage output by the first detection circuit, and corresponding compensation parameters; the data processing module calculates the resistance of the compensation electromagnetic coil based on the DC component signal output by the second DC component output circuit, and performs compensation induction signal compensation based on the resistance of the compensation electromagnetic coil, the sampling voltage output by the second detection circuit, and corresponding compensation parameters.

6. The device according to claim 5, characterized in that The data processing module performs secondary induction signal compensation according to the resistance of the secondary electromagnetic coil, the sampling voltage output by the first detection circuit and corresponding compensation parameters, including: Vst=Vs-(a1*Rs*Rs+b1*Rs+c1) Among them, Vst is the digital value of the compensated secondary induction signal, Vs is the digital value of the voltage value of the sampling voltage output by the first detection circuit, Rs is the resistance of the secondary electromagnetic coil, and a1, b1, and c1 are compensation parameters.

7. The device according to claim 5, characterized in that The data processing module performs compensation for the compensation sensing signal according to the resistance of the compensation electromagnetic coil, the sampling voltage output by the second detection circuit and the corresponding compensation parameters, including: Vct=Vc-(a2*Rc*Rc+b2*Rc+c2) Among them, Vct is the digital value of the compensated induction signal after compensation, Vc is the digital value of the voltage value of the sampling voltage output by the second detection circuit, Rc is the resistance of the compensation electromagnetic coil, and a2, b2, and c2 are compensation parameters.

8. The device according to claim 5, characterized in that The compensation parameters are obtained by iterating the complete heating and cooling data collected by performing a high and low temperature cycle test on the sensor, and then using polynomial fitting after data cleaning.

9. The device according to any one of claims 1 to 8, characterized in that The data processing module includes an analog-to-digital converter and a controller, and the analog-to-digital converter is connected to the first DC component output circuit, the second DC component output circuit, the first detection circuit, the second detection circuit and the controller.

10. A method for compensating temperature drift error of electromagnetic coil induction signal, characterized in that: The method is implemented based on the electromagnetic coil induction signal temperature drift error compensation device according to any one of claims 1 to 9, and comprises: The first DC component output circuit filters the output signal of the secondary electromagnetic coil, separates the DC component signal generated by the first constant current source and sends it to the data processing module; The first AC component output circuit filters the output signal of the secondary electromagnetic coil, separates the AC component signal of the secondary electromagnetic coil and sends it to the first detection circuit, and the first detection circuit detects the received AC component signal and outputs a sampling voltage to the data processing module; The second DC component output circuit filters the output signal of the compensation electromagnetic coil, separates the DC component signal generated by the second constant current source and sends it to the data processing module; The second AC component output circuit filters the output signal of the compensation electromagnetic coil, separates the AC component signal of the compensation electromagnetic coil and sends it to the second detection circuit, and the second detection circuit detects the received AC component signal and outputs a sampling voltage to the data processing module; The data processing module performs secondary induced signal compensation according to the DC component signal output by the first DC component output circuit and the sampled voltage output by the first detection circuit, and performs compensated induced signal compensation according to the DC component signal output by the second DC component output circuit and the sampled voltage output by the second detection circuit.

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