Method and system for extracting polarization voltage signal of electromagnetic flowmeter

Abstract

The present invention provides a method and system for extracting the polarization voltage signal of an electromagnetic flowmeter, relating to the technical field of electromagnetic flowmeters. Addressing the challenges of random drift and non-quantifiable description of polarization voltage signals, the present invention effectively extracts the polarization voltage signal from the output signal of an electromagnetic flowmeter electrode, addressing the lack of existing methods for extracting polarization voltage signals. This method provides a reference for studying the characteristics of polarization voltage signals, researching methods for suppressing polarization voltage signals, and simulating the output signal of electromagnetic flowmeter electrodes.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic flowmeters, and in particular to a method and system for extracting polarization voltage signals of electromagnetic flowmeters. Background Art

[0002] Electromagnetic flowmeter is an instrument that uses Faraday's law of electromagnetic induction to measure the flow rate of conductive liquids. It is widely used in water supply, petroleum, chemical, papermaking, metallurgy and other industries.

[0003] Polarization voltage signals (also known as polarization noise) are a type of electrode interference signal unique to electromagnetic flowmeters. Superimposed on the induced potential signal, they are picked up by the electrodes and output, significantly complicating electromagnetic flowmeter measurements. Polarization voltage signals are generated by the electrochemical reaction between the electrodes and the conductive liquid. Regardless of whether the electromagnetic flowmeter uses DC or AC excitation, polarization voltage signals are present. The amplitude of the polarization voltage signal typically ranges from a few millivolts to hundreds of millivolts and changes over time; it is not a fixed superimposed noise. The amplitude of the induced potential signal typically ranges from tens to hundreds of microvolts per unit flow rate. Therefore, directly amplifying and filtering the signal output by the sensor electrodes can easily cause amplifier saturation, preventing the electromagnetic flowmeter from accurately measuring.

[0004] However, there is currently no method to extract the polarization voltage signal. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the shortcomings of the prior art, the present invention provides a method and system for extracting polarization voltage signals of an electromagnetic flowmeter, which fills the gap that the prior art has no method for extracting polarization voltage signals.

[0007] (2) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] In a first aspect, the present invention provides a method for extracting a polarization voltage signal of an electromagnetic flowmeter, comprising:

[0010] Acquire the electrode output signal output by the signal acquisition circuit of the electromagnetic flowmeter during a period of time when measuring the flow of the conductive liquid;

[0011] A complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time is selected in chronological order, and the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle is calculated; a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle is selected in chronological order, and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle is calculated; the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle is added to the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and the average value is taken to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, each time sliding back half the length of the excitation cycle signal, the amplitude of the polarization voltage signal of each excitation current stable segment is calculated, and an amplitude sequence is formed in chronological order;

[0012] The amplitude sequence is interpolated so that the length of the interpolated amplitude sequence is equal to the length of the discretized electrode output signal. The interpolated amplitude sequence is a polarization voltage signal curve of the electrode output signal.

[0013] Preferably, the step of selecting a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in chronological order and calculating the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle includes:

[0014] The expression of the electrode output signal in the stable section of the excitation current in the positive half excitation cycle is:

[0015] Ep=BvD+e zp +e np (1a)

[0016] The expression of the electrode output signal in the stable section of the excitation current in the negative half excitation cycle is:

[0017] En=-BvD+e zn +e nn (2a)

[0018] Among them, Ep represents the output signal of the electrode in the stable section of the excitation current in the positive half cycle, e zp Represents the polarization voltage signal in the stable section of the excitation current in the positive half cycle, e np represents the Gaussian noise signal of the excitation current stable section in the positive half cycle, En represents the electrode output signal of the excitation current stable section in the negative half cycle, and e zn Indicates the polarization voltage signal in the stable section of the excitation current in the negative half cycle, e nn Represents the Gaussian noise signal in the stable section of the excitation current in the negative half cycle;

[0019] Adding equations (1a) and (2a) gives the result expressed as (3a):

[0020] Ep+En=e zp +e np +e zn +e nn (3a)

[0021] Since an excitation cycle lasts only tens to hundreds of milliseconds, according to the slow-changing characteristics of the polarization voltage, e zp Approximately equal to e zn , e np and e nn All obey the Gaussian distribution with a mean of zero, then we get formula (4a):

[0022] mean(Ep+En)=2*e zp (4a)

[0023] The amplitude of the polarization voltage signal in the stable segment of the excitation current in the positive half excitation cycle is calculated according to formula (4a).

[0024] Preferably, the interpolation processing of the amplitude sequence includes:

[0025] Perform cubic spline interpolation on the amplitude sequence; alternatively, perform linear interpolation on the amplitude sequence; or perform polynomial interpolation on the amplitude sequence.

[0026] In a second aspect, the present invention provides a system for extracting polarization voltage signals of an electromagnetic flowmeter, comprising:

[0027] A signal acquisition module is used to acquire the electrode output signal output by the electromagnetic flowmeter via the signal acquisition circuit within a period of time when measuring the flow rate of the conductive liquid;

[0028] An amplitude calculation module is used to select a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in a time sequence, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle; select a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle in a time sequence, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle; add the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and then take the average value to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, sliding backward by half the length of the excitation cycle signal each time, calculate the amplitude of the polarization voltage signal of each excitation current stable segment, and form an amplitude sequence in a time sequence;

[0029] The interpolation module is used to perform interpolation processing on the amplitude sequence so that the length of the interpolated amplitude sequence is equal to the length of the electrode output signal after discretization. The interpolated amplitude sequence is the polarization voltage signal curve of the electrode output signal.

[0030] Preferably, the step of selecting a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in chronological order and calculating the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle includes:

[0031] The expression of the electrode output signal in the stable section of the excitation current in the positive half excitation cycle is:

[0032] Ep=BvD+e zp +e np (1a)

[0033] The expression of the electrode output signal in the stable section of the excitation current in the negative half excitation cycle is:

[0034] En=-BvD+e zn +e nn (2a)

[0035] Among them, Ep represents the output signal of the electrode in the stable section of the excitation current in the positive half cycle, e zp Represents the polarization voltage signal in the stable section of the excitation current in the positive half cycle, e np represents the Gaussian noise signal of the excitation current stable section in the positive half cycle, En represents the electrode output signal of the excitation current stable section in the negative half cycle, and e zn Indicates the polarization voltage signal in the stable section of the excitation current in the negative half cycle, e nn Represents the Gaussian noise signal in the stable section of the excitation current in the negative half cycle;

[0036] Adding equations (1a) and (2a) gives the result expressed as (3a):

[0037] Ep+En=e zp +e np +e zn +e nn (3a)

[0038] Since an excitation cycle lasts only tens to hundreds of milliseconds, according to the slow-changing characteristics of the polarization voltage, e zp Approximately equal to e zn , e np and e nn All obey the Gaussian distribution with a mean of zero, then we get formula (4a):

[0039] mean(Ep+En)=2*e zp(4a)

[0040] The amplitude of the polarization voltage signal in the stable segment of the excitation current in the positive half excitation cycle is calculated according to formula (4a).

[0041] Preferably, the interpolation processing of the amplitude sequence includes:

[0042] Perform cubic spline interpolation on the amplitude sequence; alternatively, perform linear interpolation on the amplitude sequence; or perform polynomial interpolation on the amplitude sequence.

[0043] In a third aspect, the present invention provides a computer-readable storage medium storing a computer program for extracting a polarization voltage signal of an electromagnetic flowmeter, wherein the computer program enables a computer to execute the method for extracting a polarization voltage signal of an electromagnetic flowmeter as described above.

[0044] In a fourth aspect, the present invention provides an electronic device, comprising:

[0045] One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the programs include a method for extracting the polarization voltage signal of the electromagnetic flowmeter as described above.

[0046] (3) Beneficial effects

[0047] The present invention provides a method and system for extracting polarization voltage signals from an electromagnetic flowmeter. Compared with the prior art, the method and system have the following advantages:

[0048] In response to the problem of random drift and non-quantifiable description of polarization voltage signals, the present invention effectively extracts the polarization voltage signal from the output signal of the electromagnetic flowmeter electrode, filling the gap that there is no method for extracting polarization voltage signals in the existing technology, and providing a reference for studying the characteristics of polarization voltage signals, studying the suppression method of polarization voltage signals and simulating the output signal of the electromagnetic flowmeter electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 This is a block diagram of a method for extracting polarization voltage signals of an electromagnetic flowmeter according to an embodiment of the present invention;

[0051] Figure 2It is a schematic diagram of the excitation current curve and induced potential signal curve of the electromagnetic flowmeter using square wave excitation;

[0052] Figure 3 It is a schematic diagram of the signal waveform output by the electromagnetic flowmeter electrode;

[0053] Figure 4 It is a schematic diagram of the signal waveform details output by the electromagnetic flowmeter electrode;

[0054] Figure 5 is the extracted polarization voltage signal curve;

[0055] Figure 6 It is the electrode output signal curve after removing the polarization voltage signal. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0057] The embodiments of the present application provide a method and system for extracting the polarization voltage signal of an electromagnetic flowmeter, thereby filling the gap in the prior art in that there is no method for extracting the polarization voltage signal, and effectively extracting the polarization voltage signal from the output signal of the electromagnetic flowmeter electrode, providing a reference for studying the characteristics of the polarization voltage signal, studying the method for suppressing the polarization voltage signal, and simulating the output signal of the electromagnetic flowmeter electrode.

[0058] The technical solution in the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0059] Polarization voltage signals are unavoidable interference signals in electromagnetic flowmeter measurements. They must be considered when designing signal conditioning circuits and overcome when developing measurement algorithms. Polarization voltage signals are random signals with low-frequency drift and cannot be quantitatively described. To gain an intuitive understanding of polarization voltage, study its characteristics, investigate its suppression methods, and simulate electromagnetic flowmeter electrode output signals, the present invention proposes a method for extracting polarization voltage signals from electromagnetic flowmeters using square wave excitation. This method exploits the slow-varying nature of polarization voltage signals, meaning that the amplitude of the polarization voltage signal within an excitation cycle can be assumed to be approximately equal. During electromagnetic flowmeter measurement, the electrode output signal includes an induced potential signal, differential interference, cross-mode interference, common-mode interference, polarization voltage signals, and Gaussian noise. After processing the signal conditioning circuit, both cross-mode interference and common-mode interference are effectively suppressed. The differential interference signal is primarily distributed during the rising phase of the excitation current. The induced potential signal has the best signal-to-noise ratio during the stable phase of the excitation current. The polarization voltage signal is a randomly drifting signal with a large amplitude that is distributed throughout each excitation cycle. The Gaussian noise signal has a very small amplitude and, like the polarization voltage signal, is distributed throughout each excitation cycle. The magnitude of the polarization voltage signal during the stable excitation current segment of an excitation cycle is equal to the sum of the signals during the stable excitation current segment of the positive half-cycle and the stable excitation current segment of the negative half-cycle within that excitation cycle, and the average value is calculated. The method for calculating the polarization voltage signal amplitude during the stable excitation current segment of an excitation cycle can be used to calculate the polarization voltage signal amplitude during the stable excitation current segment of all excitation cycles. The polarization voltage signal exists not only during the stable excitation current segment but also during the rising excitation current segment. Therefore, using the calculated polarization voltage signal amplitude during the stable excitation current segment as a sample, cubic spline interpolation is performed to calculate the polarization voltage signal of the electromagnetic flowmeter sensor electrode output signal. The calculated polarization voltage signal amplitudes for the stable excitation current segments of all excitation cycles are organized into an amplitude sequence in chronological order. This sequence is then interpolated using cubic spline interpolation to ensure that the length of the interpolated amplitude sequence is equal to the length of the discrete amplitude of the electrode output signal. This yields the polarization voltage curve for the electrode output signal.

[0060] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0061] An embodiment of the present invention provides a method for extracting a polarization voltage signal of an electromagnetic flowmeter, the method comprising:

[0062] S1. Obtaining an electrode output signal output by a signal acquisition circuit of an electromagnetic flowmeter during a period of time when measuring the flow rate of a conductive liquid;

[0063] S2. Select a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle; select a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle; add the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and then take the average value to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, sliding backward by half the length of the excitation cycle signal each time, calculate the amplitude of the polarization voltage signal of each excitation current stable segment, and form an amplitude sequence in chronological order;

[0064] S3. Interpolate the amplitude sequence so that the length of the interpolated amplitude sequence is equal to the length of the discretized electrode output signal. The interpolated amplitude sequence is a polarization voltage signal curve of the electrode output signal.

[0065] To address the problem of random drift and non-quantifiable description of polarization voltage signals, the embodiments of the present invention can effectively extract polarization voltage signals from the output signals of electromagnetic flowmeter electrodes, filling the gap in the existing technology that there is no method for extracting polarization voltage signals, and providing a reference for studying the characteristics of polarization voltage signals, studying methods for suppressing polarization voltage signals, and simulating the output signals of electromagnetic flowmeter electrodes.

[0066] Before describing each step in detail, the excitation current curve and induced potential signal curve of the electromagnetic flowmeter are explained:

[0067] Figure 2 The diagram below shows the excitation current curve and induced potential signal curve of an electromagnetic flowmeter using square wave excitation. The waveform of the induced potential signal of the electromagnetic flowmeter is determined by the waveform of the excitation current. When the flow rate of the conductive liquid flowing through the sensor pipe remains unchanged, the excitation current curve and induced potential signal curve of the electromagnetic flowmeter using square wave excitation are shown in the figure below. Figure 2 As shown in the figure, the excitation current curve and induced electromotive force signal curve of two complete excitation cycles are included in the figure. Square wave excitation is a realization of AC excitation. Each excitation cycle of square wave excitation consists of a positive half excitation cycle and a negative half excitation cycle. The excitation current curves of the positive half excitation cycle and the negative half excitation cycle have the same change process except that the polarity is opposite. Since the excitation current cannot change suddenly, the excitation current includes a rising section and a stable section regardless of the positive half excitation cycle or the negative half excitation cycle, as shown in Figure 2. Figure 2 t in r and t sThe electromagnetic flowmeter performs measurement in the stable section of the excitation current, because in the stable section of the excitation current, the signal-to-noise ratio of the induced potential signal in the electrode output signal is the best.

[0068] The following describes each step in detail:

[0069] In one embodiment, S1, obtaining an electrode output signal output by a signal acquisition circuit of an electromagnetic flowmeter during a period of time when measuring the flow rate of a conductive liquid, specifically includes:

[0070] In the embodiment of the present invention, in order to more intuitively understand the signal output by the electromagnetic flowmeter electrode, it is observed and analyzed in combination with the actual signal. A signal of a period of 450 seconds is collected and saved. This signal is output by the electromagnetic flowmeter through the signal acquisition circuit under a fixed flow rate. The saved electrode output signal is plotted without any processing. The time domain diagram of the electrode output signal under a fixed flow rate is as follows: Figure 3 It should be noted that, in the specific implementation process, the signal of the non-fixed flow rate state can also be used as the signal for observation and analysis. In the embodiment of the present invention, the electrode output signal under the fixed flow rate state is used as the material for detailed description.

[0071] When the electromagnetic flowmeter is actually used, in addition to the induced potential signal which is proportional to the flow velocity, the signal output by the electrode also contains differential interference signals, cross-mode interference, common-mode interference, polarization voltage signals and Gaussian noise signals, which can be expressed using formula (1).

[0072]

[0073] Where, E represents the signal output by the electrode, B represents the magnetic field strength in the sensor pipe, v represents the flow rate of the conductive liquid in the sensor pipe, D represents the diameter of the sensor pipe, and BvD represents the induced potential signal that is proportional to the flow rate. represents the differential interference signal, e c Represents the common mode interference signal, e d Indicates the cross-mode interference signal, e z Represents the polarization voltage signal, e nRepresents a Gaussian noise signal. Differential interference signals primarily exist in the rising phase of the excitation current, while electromagnetic flowmeters primarily use the induced potential signal during the stable phase of the excitation current. Therefore, electromagnetic flowmeters can avoid the impact of differential interference signals on measurement. Common-mode interference signals and cross-mode interference signals can be effectively suppressed by using differential, high-common-mode rejection ratio amplifier circuits, signal conditioning circuits, and good grounding. The polarization voltage signal is a low-frequency drift interference signal with an amplitude far greater than the induced potential signal associated with flow. Its frequency is also very close to the electromagnetic flowmeter excitation frequency of only a few hertz to a dozen hertz, making it difficult to separate from the induced potential signal using hardware circuits, seriously affecting the extraction of the induced potential signal. Gaussian noise is a random noise with an amplitude that follows a zero-mean Gaussian distribution. Effective suppression can be achieved by sampling multiple signal points during the stable phase of the excitation current and then averaging these multiple signal points.

[0074] In one embodiment, S2, a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time is selected in chronological order, and the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle is calculated; a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle is selected in chronological order, and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle is calculated; the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle is added to the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and the average value is taken to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, each time sliding back half the length of the excitation cycle signal, the amplitude of the polarization voltage signal of each excitation current stable segment is calculated, and an amplitude sequence is formed in chronological order. Specifically including:

[0075] Within an excitation cycle, first calculate the average value of the electrode's output signal during the excitation current stability period of the positive half-cycle. Then calculate the average value of the electrode's output signal during the excitation current stability period of the negative half-cycle. Finally, average these two average values ​​to obtain the magnitude of the polarization voltage signal output by the electrode within the excitation cycle. The magnitude of the polarization voltage calculated for a complete excitation cycle consisting of the positive and negative half-cycles is called the polarization voltage signal amplitude during the excitation current stability period of the positive half-cycle. The magnitude of the polarization voltage calculated for a complete excitation cycle consisting of the negative and positive half-cycles is called the polarization voltage signal amplitude during the excitation current stability period of the negative half-cycle. Similarly, sliding backward by half the length of the excitation cycle signal, the polarization voltage signal amplitude for each excitation current stability period is calculated and organized into an amplitude sequence in chronological order.

[0076] Figure 4This is a schematic diagram of the signal waveform details of the electromagnetic flowmeter electrode output. Figure 3 The induced potential signal containing two complete excitation cycles is obtained by local amplification. The details of the electrode output time domain signal are shown in the figure below. Figure 4 As shown. Figure 4 The differential interference signal and induced potential signal are clearly visible in the electrode output signal. During the rising phase of the excitation current, the electrode output signal is primarily differential interference; during the stable phase of the excitation current, the electrode output signal is primarily induced potential signal. The Gaussian noise signal has a very small amplitude and is distributed throughout each excitation cycle. Figure 4 The polarization voltage signal cannot be clearly seen because, compared with the induced potential signal, the polarization voltage signal is a slow-changing signal and no obvious changes can be seen in a short period of time. Figure 3 It is clear that there is a polarization voltage signal in the electrode output signal, which drifts randomly with the induced potential signal. If the electromagnetic flowmeter detects that the signal amplitude entering the signal conditioning circuit is too large, it will promptly compensate the electrode output signal to ensure that the electrode output signal does not saturate the amplifier in the signal conditioning circuit.

[0077] exist Figure 4 In the figure, the signals of a complete excitation cycle consisting of the positive half excitation cycle in dashed box a and the negative half excitation cycle in dashed box b can be used to calculate the amplitude of the polarization voltage signal during the stable segment of the positive half excitation cycle in dashed box a. The signals of a complete excitation cycle consisting of the negative half excitation cycle in dashed box b and the positive half excitation cycle in dashed box c can be used to calculate the amplitude of the polarization voltage signal during the stable segment of the negative half excitation cycle in dashed box b. The method for calculating the amplitude of the polarization voltage signal during the stable segment of the excitation current in the positive half excitation cycle in dashed box a is as follows.

[0078] The electrode output signal in the excitation current stable section of the positive half excitation cycle can be expressed by formula (2). The electrode output signal in the excitation current stable section of the negative half cycle can be expressed by formula (3).

[0079] Ep=BvD+e zp +e np (2)

[0080] En=-BvD+e zn +e nn (3)

[0081] Among them, Ep represents the output signal of the electrode in the stable section of the excitation current in the positive half cycle, e zp Represents the polarization voltage signal in the stable section of the excitation current in the positive half cycle, e nprepresents the Gaussian noise signal of the excitation current stable section in the positive half cycle, En represents the electrode output signal of the excitation current stable section in the negative half cycle, and e zn Indicates the polarization voltage signal in the stable section of the excitation current in the negative half cycle, e nn The Gaussian noise signal in the stable section of the excitation current in the negative half cycle is represented by Equation (4) by adding Equation (2) and Equation (3) together.

[0082] Ep+En=e zp +e np +e zn +e nn (4)

[0083] Since an excitation cycle lasts only tens to hundreds of milliseconds, according to the slow-changing characteristics of the polarization voltage, e zp It can be approximately equal to e zn , e np and e nn All obey the Gaussian distribution with a mean of zero, then we can get formula (5).

[0084] mean(Ep+En)=2*e zp (5)

[0085] According to formula (5), the amplitude of the polarization voltage signal in the stable excitation current section of the positive half excitation cycle, where the dotted box a is located, can be calculated. This is equal to the average value of the electrode output signal in the stable excitation current section of the positive half excitation cycle, where the dotted box a is located, and the electrode output signal in the stable excitation current section of the negative half excitation cycle, where the dotted box b is located. Similarly, the amplitude of the polarization voltage signal in the stable excitation current section of the negative half excitation cycle, where the dotted box b is located, can be calculated.

[0086] Therefore, the magnitude of the polarization voltage signal in the stable segment of the excitation current in an excitation cycle is equal to the sum of the signal of the stable segment of the positive half cycle of the excitation current and the signal of the stable segment of the negative half cycle of the excitation current in this excitation cycle and the average value thereof.

[0087] Then calculate the amplitude of the polarization voltage signal in the stable segment of the excitation current of all excitation cycles. According to the method of calculating the amplitude of the polarization voltage signal in the stable segment of the excitation current of one excitation cycle, the amplitude of the polarization voltage signal in the stable segment of the excitation current of all excitation cycles can be calculated by analogy.

[0088] In one embodiment, S3, interpolation processing is performed on the amplitude sequence so that the length of the interpolated amplitude sequence is equal to the length of the discretized electrode output signal, and the interpolated amplitude sequence is a polarization voltage signal curve of the electrode output signal. Specifically, it includes:

[0089] The polarization voltage signal exists not only in the stable section of the excitation current, but also in the rising section of the excitation current. Therefore, the polarization voltage signal amplitude of the calculated stable section of the excitation current is used as a sample, and cubic spline interpolation is performed on it to calculate the polarization voltage signal of the electrode output signal of the electromagnetic flowmeter sensor. The amplitudes of the polarization voltage signals of the stable section of the excitation current of all excitation cycles are combined into an amplitude sequence in chronological order, and the composed amplitude sequence is subjected to cubic spline interpolation so that the length of the interpolated amplitude sequence is equal to the length of the amplitude of the electrode output signal after discretization. In this way, the curve of the polarization voltage signal of the electrode output signal is obtained. It should be noted that in the specific implementation process, the interpolation processing method also includes linear interpolation, polynomial interpolation and other methods.

[0090] Figure 5 The polarization voltage signal curve is extracted. The calculation method of the polarization voltage signal based on cubic spline interpolation is used to extract Figure 3 The electrode output signal in the figure is as follows: Figure 5 As shown in Figure 2, it can be seen that the variation trend of the extracted polarization voltage signal curve is consistent with the variation trend of the signal output by the sensor electrode.

[0091] Figure 6 This is the electrode output signal curve after the polarization voltage signal is removed. If the polarization voltage signal in the sensor electrode output signal is removed, the electrode output signal after the polarization voltage signal is removed is as follows: Figure 6 As shown in the figure, it can be seen that the electrode output signal after removing the polarization voltage signal is evenly distributed on both sides of the straight line with an amplitude of 0. Therefore, the proposed calculation method of the polarization voltage signal based on cubic spline interpolation can effectively extract the polarization voltage signal from the electrode output signal of the electromagnetic flowmeter sensor.

[0092] An embodiment of the present invention further provides a system for extracting polarization voltage signals of an electromagnetic flowmeter, comprising:

[0093] A signal acquisition module is used to acquire the electrode output signal output by the electromagnetic flowmeter via the signal acquisition circuit within a period of time when measuring the flow rate of the conductive liquid;

[0094] An amplitude calculation module is used to select a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in a time sequence, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle; select a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle in a time sequence, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle; add the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and then take the average value to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, sliding backward by half the length of the excitation cycle signal each time, calculate the amplitude of the polarization voltage signal of each excitation current stable segment, and form an amplitude sequence in a time sequence;

[0095] The interpolation module is used to perform interpolation processing on the amplitude sequence so that the length of the interpolated amplitude sequence is equal to the length of the electrode output signal after discretization. The interpolated amplitude sequence is the polarization voltage signal curve of the electrode output signal.

[0096] It is understandable that the electromagnetic flowmeter polarization voltage signal extraction system provided in the embodiment of the present invention corresponds to the above-mentioned electromagnetic flowmeter polarization voltage signal extraction method. The explanation, examples, beneficial effects, etc. of the relevant contents can refer to the corresponding contents in the electromagnetic flowmeter polarization voltage signal extraction method, and will not be repeated here.

[0097] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program for extracting a polarization voltage signal of an electromagnetic flowmeter, wherein the computer program enables a computer to execute the method for extracting a polarization voltage signal of an electromagnetic flowmeter as described above.

[0098] An embodiment of the present invention also provides an electronic device, comprising: one or more processors; a memory; and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the programs include a method for executing the extraction method of the polarization voltage signal of the electromagnetic flowmeter as described above.

[0099] In summary, compared with the existing technology, the present invention has the following beneficial effects:

[0100] To address the problem of random drift and non-quantifiable description of polarization voltage signals, the embodiments of the present invention can effectively extract polarization voltage signals from the output signals of electromagnetic flowmeter electrodes, filling the gap in the existing technology that there is no method for extracting polarization voltage signals, and providing a reference for studying the characteristics of polarization voltage signals, studying methods for suppressing polarization voltage signals, and simulating the output signals of electromagnetic flowmeter electrodes.

[0101] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for extracting polarization voltage signals of an electromagnetic flowmeter, characterized in that: include: Acquire the electrode output signal output by the signal acquisition circuit of the electromagnetic flowmeter during a period of time when measuring the flow of the conductive liquid; A complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time is selected in chronological order, and the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle is calculated; a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle is selected in chronological order, and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle is calculated; the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle is added to the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and the average value is taken to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, each time sliding back half the length of the excitation cycle signal, the amplitude of the polarization voltage signal of each excitation current stable segment is calculated, and an amplitude sequence is formed in chronological order; The amplitude sequence is interpolated so that the length of the interpolated amplitude sequence is equal to the length of the discretized electrode output signal. The interpolated amplitude sequence is a polarization voltage signal curve of the electrode output signal.

2. The method for extracting the polarization voltage signal of an electromagnetic flowmeter according to claim 1, wherein: The method of selecting a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in chronological order and calculating the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle includes: The expression of the electrode output signal in the stable section of the excitation current in the positive half excitation cycle is: Ep6BvD+e zp +e np (1a) The expression of the electrode output signal in the stable section of the excitation current in the negative half excitation cycle is: En=-BvD+e zn +e nn (2nd) Among them, Ep represents the output signal of the electrode in the stable section of the excitation current in the positive half cycle, e zp Represents the polarization voltage signal in the stable section of the excitation current in the positive half cycle, e np represents the Gaussian noise signal of the excitation current stable section in the positive half cycle, En represents the electrode output signal of the excitation current stable section in the negative half cycle, and e zn Indicates the polarization voltage signal in the stable section of the excitation current in the negative half cycle, e nn Represents the Gaussian noise signal in the stable section of the excitation current in the negative half cycle; Adding equations (1a) and (2a) gives the result expressed as (3a): Ep+En=e zp +e np +e zn +e nn (3a) Since an excitation cycle lasts only tens to hundreds of milliseconds, according to the slow-changing characteristics of the polarization voltage, e zp Approximately equal to e zn , e np and e nn All obey the Gaussian distribution with a mean of zero, then we get formula (4a): mean(Ep+En)=2*e zp (4a) The amplitude of the polarization voltage signal in the stable segment of the excitation current in the positive half excitation cycle is calculated according to formula (4a).

3. The method for extracting the polarization voltage signal of an electromagnetic flowmeter according to claim 1 or 2, wherein: The interpolation processing of the amplitude sequence includes: Perform cubic spline interpolation on the amplitude sequence; alternatively, perform linear interpolation on the amplitude sequence; or perform polynomial interpolation on the amplitude sequence.

4. A system for extracting polarization voltage signals of an electromagnetic flowmeter, characterized in that: include: A signal acquisition module is used to acquire the electrode output signal output by the electromagnetic flowmeter via the signal acquisition circuit within a period of time when measuring the flow rate of the conductive liquid; An amplitude calculation module is used to select a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in a time sequence, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle; select a complete excitation cycle signal consisting of a negative half excitation cycle and a positive half excitation cycle in a time sequence, and calculate the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle; add the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle and the polarization voltage signal amplitude of the excitation current stable segment of the negative half excitation cycle, and then take the average value to obtain the amplitude of the polarization voltage signal of the excitation current stable segment of an excitation cycle; and so on, sliding backward by half the length of the excitation cycle signal each time, calculate the amplitude of the polarization voltage signal of each excitation current stable segment, and form an amplitude sequence in a time sequence; The interpolation module is used to perform interpolation processing on the amplitude sequence so that the length of the interpolated amplitude sequence is equal to the length of the electrode output signal after discretization. The interpolated amplitude sequence is the polarization voltage signal curve of the electrode output signal.

5. The system for extracting polarization voltage signals of an electromagnetic flowmeter according to claim 4, characterized in that: The method of selecting a complete excitation cycle signal consisting of a positive half excitation cycle and a negative half excitation cycle within a period of time in chronological order and calculating the polarization voltage signal amplitude of the excitation current stable segment of the positive half excitation cycle includes: The expression of the electrode output signal in the stable section of the excitation current in the positive half excitation cycle is: Ep6BvD+e zp +e np (1a) The expression of the electrode output signal in the stable section of the excitation current in the negative half excitation cycle is: En=-BvD+e zn +e nn (2nd) Among them, Ep represents the output signal of the electrode in the stable section of the excitation current in the positive half cycle, e zp Represents the polarization voltage signal in the stable section of the excitation current in the positive half cycle, e np represents the Gaussian noise signal of the excitation current stable section in the positive half cycle, En represents the electrode output signal of the excitation current stable section in the negative half cycle, and e zn Indicates the polarization voltage signal in the stable section of the excitation current in the negative half cycle, e nn Represents the Gaussian noise signal in the stable section of the excitation current in the negative half cycle; Adding equations (1a) and (2a) gives the result expressed as (3a): Ep+En=e zp +e np +e zn +e nn (3a) Since an excitation cycle lasts only tens to hundreds of milliseconds, according to the slow-changing characteristics of the polarization voltage, e zp Approximately equal to e zn , e np and e nn All obey the Gaussian distribution with a mean of zero, then we get formula (4a): mean(Ep+En)=2*e zp (4a) The amplitude of the polarization voltage signal in the stable segment of the excitation current in the positive half excitation cycle is calculated according to formula (4a).

6. The system for extracting polarization voltage signals of an electromagnetic flowmeter according to claim 4 or 5, characterized in that: The interpolation processing of the amplitude sequence includes: Perform cubic spline interpolation on the amplitude sequence; alternatively, perform linear interpolation on the amplitude sequence; or perform polynomial interpolation on the amplitude sequence.

7. A computer-readable storage medium, characterized in that The computer program for extracting the polarization voltage signal of the electromagnetic flowmeter is stored, wherein the computer program enables the computer to execute the method for extracting the polarization voltage signal of the electromagnetic flowmeter according to any one of claims 1 to 3.

8. An electronic device, characterized in that: include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the programs include a method for executing the extraction method of the polarization voltage signal of the electromagnetic flowmeter according to any one of claims 1 to 3.

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