CN108645489A - A kind of quick zero point compensation method of electromagnetic flow-measurement - Google Patents
A kind of quick zero point compensation method of electromagnetic flow-measurement Download PDFInfo
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- CN108645489A CN108645489A CN201810393600.7A CN201810393600A CN108645489A CN 108645489 A CN108645489 A CN 108645489A CN 201810393600 A CN201810393600 A CN 201810393600A CN 108645489 A CN108645489 A CN 108645489A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
- G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters
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Abstract
The present invention provides a kind of quick zero point compensation method of electromagnetic flow-measurement, including：Directly zero state signal is acquired, the offset of signal base line is obtained according to collection result；Actual zero point is obtained according to the offset of the signal base line；Practical measurement signals are acquired, and in real time compensate the actual zero point into actual signal, complete quick zero compensation；The present invention can overcome orthogonal interference, polarization interference, vortex interference, the influence of the interference such as common mode interference and external environment to zero in high-speed excitation；Improve signal-to-noise ratio by multi-signal control and treatment technology and null offset caused by reducing the influence of external environment enhance the zero stability of instrument by the quick compensation to zero signal, ensure that instrument flow velocity section measurement accuracy.
Description
Technical field
The present invention relates to electronic field more particularly to a kind of quick zero point compensation methods of electromagnetic flow-measurement.
Background technology
Electromagnetic flowmeter is to apply electromagnetic induction principle, according to conductor fluid by the electromotive force inducted when externally-applied magnetic field come
A kind of instrument for measuring conductor fluid flow, in measurement process, in order to reduce electric polarization interference, it will usually use alternating magnetic field
Mode into row energization, but since coil can bring inductive effect, so the variation of exciting current can follow inductance operation principle,
In current break, inductance will produce the variation that inverse electromotive force hinders electric current, cause electric current that can not quickly reach the stabilization of load
State, the state can be interacted by the voltage loaded, the resistance and inductance of coil.
Currently, both at home and abroad tradition electromagnetic flowmeter mostly use low frequency excitation technology exciting current stable state region measurement or
It forces in the short time to improve electric current to stablizing shape by increasing excitation voltage to the improvement of field circuit when improving excitation frequency
State measures；But due to exciting current in propradation can magnetic field be variation, at this time magnetic field by it is a variety of it is external because
The interference of element, causes signal can be with the shadow of the factors such as temperature, time, ground connection, vortex, Medium impedence, electrode polarization, signal cross-talk
Ring, can not obtain as exciting current at steady state as repeatability and linear, increase the difficulty of signal processing.In order to gram
The stably measured problem of signal under excited state in short-term is taken, existing solution generally takes two schemes, the first is logical
It crosses increasing excitation voltage and forces fast lifting exciting current, but this kind of big calorific value of method power consumption is larger, be unfavorable for similar battery
It is used under the conditions of power supply low-power consumption, and calorific value can also bring the long-time service of instrument hidden danger, second is by using instead
The sensor of other structures using electromagnet as provided magnetic field, by after encouraging in short-term, utilizing electromagnet to electromagnet charging
Remanent magnetism the magnetic field needed for signal is provided, but the program is due to very high to sensor requirements, can not also find at home corresponding
Material and technique, and it is applicable in effect and also needs time check, and therefore, it is necessary to quick the zero of a kind of new electromagnetic flow-measurement
Point compensation method improves signal-to-noise ratio and reduces null offset caused by the influence of external environment, ensures instrument in low flow velocity section
Measurement accuracy.
Invention content
In view of the foregoing deficiencies of prior art, the present invention provides a kind of quick zero compensation side of electromagnetic flow-measurement
Method, to solve the above technical problems.
The quick zero point compensation method of electromagnetic flow-measurement provided by the invention, including：
Directly zero state signal is acquired, the offset of signal base line is obtained according to collection result；
Actual zero point is obtained according to the offset of the signal base line；
Practical measurement signals are acquired, and in real time compensate the actual zero point into actual signal, quick zero is completed and mends
It repays.
Further, the measurement point for acquiring zero state signal different conditions is pre-set, is believed at one according to zero state signal
Measured value in number period obtains the offset of the signal base line, and becomes using the offset of the signal base line as linear
Amount eliminates the offset of actual zero point and the signal base line by carrying out signal processing to the measured value in the zero state signal period
Amount.
Further, the signal processing includes carrying out in the following way：
(A2-A4)-(A1-A3)
Wherein, A1 be the first zero cross signal, A2 in the zero state signal period be wave crest signal, A3 be the second zero cross signal and
A4 is trough signal.
Further, the signal processing further includes directly carrying out modulus by analog-to-digital conversion module to practical measurement signals to turn
It changes, and low-pass filtering treatment is carried out to the signal after analog-to-digital conversion.
Further, the exciting current signal and differential interference signal when acquisition zeroing, by practical measurement signals
Differential interference signal and exciting current signal carry out pectination bandpass filtering, retain odd harmonic cancellation even-order harmonic and direct current is inclined
It sets, obtains differential interference signal in practical measurement signals, according to differential interference letter in the actual zero point and practical measurement signals
Number, obtain the true zero signal of practical measurement signals.
When differential interference signal and exciting current signal carry out pectination bandpass filtering when further, to zeroing, one is obtained
The signal data in period, and the signal data in the period replicate and is used as follow-up data, to meet in terms of pectination bandpass filtering
The data volume of calculation.
Further, by practical measurement signals differential interference signal and exciting current signal carry out pectination band logical filter
After wave, the exciting current signal is reconstructed with practical measurement signals frequency, obtains the exciting current signal after reconstruct.
Beneficial effects of the present invention：The quick zero point compensation method of electromagnetic flow-measurement in the present invention, can be quick
When excitation, the shadow of orthogonal interference, polarization interference, vortex interference, the interference such as common mode interference and external environment to zero is overcome
It rings；Signal-to-noise ratio and null offset caused by reducing the influence of external environment are improved by multi-signal control and treatment technology, is led to
Cross the quick compensation to zero signal, enhance the zero stability of instrument, ensure that instrument flow velocity section measurement accuracy.
Description of the drawings
Fig. 1 is the measuring signal baseline schematic diagram of normal condition in the embodiment of the present invention.
Fig. 2 is the baseline schematic diagram of actual signal after being interfered influence in the embodiment of the present invention.
Fig. 3 signal contrast schematic diagrames, it is actual measurement zero signal oscillogram that upper half part, which is in the embodiment of the present invention,；Lower half
Part is oscillogram of the original signal after pectination bandpass filtering.
Fig. 4 is the spectrum diagram that zero signal is surveyed in the embodiment of the present invention.
Fig. 5 is the spectrum diagram of original signal signal after comb band-pass filter in the embodiment of the present invention.
Fig. 6 is spectrum diagram of the signal after Fourier expansion in the embodiment of the present invention.
Fig. 7 is frequency spectrum of the signal shown in Fig. 6 after Fourier expansion in the embodiment of the present invention.
Fig. 8 is the exciting current signal schematic representation obtained after being reconstructed in the embodiment of the present invention.
Fig. 9 is the odd times times harmonic wave that the exciting current signal obtained after being reconstructed in the embodiment of the present invention contains only signal frequency
Spectrum diagram.
Figure 10 is the cross-correlation coefficient schematic diagram of differential interference signal and exciting current signal in the embodiment of the present invention.
Figure 11 is practical zero differential interference schematic diagram in the embodiment of the present invention.
Figure 12 is practical exciting current change schematic diagram in the embodiment of the present invention.
Specific implementation mode
Illustrate that embodiments of the present invention, those skilled in the art can be by this specification below by way of specific specific example
Disclosed content understands other advantages and effect of the present invention easily.The present invention can also pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also be based on different viewpoints with application, without departing from
Various modifications or alterations are carried out under the spirit of the present invention.It should be noted that in the absence of conflict, following embodiment and implementation
Feature in example can be combined with each other.
It should be noted that the diagram provided in following embodiment only illustrates the basic structure of the present invention in a schematic way
Think, component count, shape and size when only display is with related component in the present invention rather than according to actual implementation in schema then
Draw, when actual implementation kenel, quantity and the ratio of each component can be a kind of random change, and its assembly layout kenel
It is likely more complexity.
The quick zero point compensation method of electromagnetic flow-measurement in the present embodiment, including：
Directly zero state signal is acquired, the offset of signal base line is obtained according to collection result；
Actual zero point is obtained according to the offset of the signal base line；
Practical measurement signals are acquired, and in real time compensate the actual zero point into actual signal, quick zero is completed and mends
It repays.
As shown in Figure 1, the measurement point for acquiring zero state signal different conditions is pre-set, according to zero state signal at one
Measured value in signal period obtains the offset of the signal base line, and becomes using the offset of the signal base line as linear
Amount eliminates the offset of actual zero point and the signal base line by carrying out signal processing to the measured value in the zero state signal period
Amount.The present embodiment acquires traditional ternary signal and is adjusted with processing mode, and zero state signal acquisition is put into practical letter
Number front end complete, the data for then calculating zero state signal are used as actual zero point, compensate in actual signal, due to
Afterflow and the influence of temperature cause A1 and A3 not fully zero passage, same interference signal to be also contained in the measurement point of A2 and A4,
Therefore the spurious signal between A2 and A4 is eliminated by the way of (A2-A4)-(A1-A3).The common mode brought by sensor
The baseline of the influence actual signal of interference is slowly varying as shown in Fig. 2, between A2 and A4, can be contained between also A1 and A3
The transformation of the offset of one signal base line, this offset is slow, in a short time as linear；It is obtaining
After the information of the above A1 to A4, it can be seen that A1-A3 is actual zero point, the offset for including between them, between A2-A4
Equally also include that actual zero point and the offset information can be eliminated simultaneously by way of (A2-A4)-(A1-A3)；It is protected with this
Demonstrate,prove the stability of zero.
In the present embodiment, signal processing further includes directly carrying out modulus by analog-to-digital conversion module to practical measurement signals
Conversion, and low-pass filtering treatment is carried out to the signal after analog-to-digital conversion, due to the usually very high 100Hz of excitation signal frequency in short-term~
500Hz is increased retrospect signal and changes rule with sensor if being be easy to cause the distortion of signal using traditional filter amplification circuit
The difficulty of rule；The present embodiment abandons prime filter amplification circuit, and signal is introduced directly into high-precision integration type analog-to-digital conversion
Circuit module, it is preferable that the digit of the conversion module in the present embodiment can reach 32, amplify 32 by internal amplification circuit
It after times, then is filtered by the lowpass digital filter of a single order, then change data is transferred to after MCU carries out
Continuous signal processing, as shown in figure 3, Fig. 3 upper half parts are actual measurement zero signal oscillograms；Lower portion is original signal by comb
Oscillogram after shape bandpass filtering surveys the frequency spectrum of zero signal as shown in figure 4, the frequency spectrum is humorous again by the odd times of signal frequency
Wave is constituted with even times harmonic wave plus direct current biasing, frequency spectrum such as Fig. 5 institutes of original signal signal after comb band-pass filter
Show, which contains only the odd times times harmonic wave of signal frequency, and in the present embodiment, Fig. 7 is to assume the Europe sensor resistance R=50
Nurse, exponential function in the case of inductance L=0.2HSignal shown in the Fig. 6 obtained after being reconstructed with signal frequency passes through Fu
In frequency spectrum after leaf expansion, which contains only the odd times times harmonic wave of signal frequency.By the way that Fig. 5 and Fig. 7 and Fig. 4 is compared
It was found that differential interferes and does not contain direct current biasing and even-order harmonic component, the DC component in circuit and this even harmonic component be by
It is caused in the asymmetry of circuit system；Fig. 8 assumes that R=50 ohm, inductance L=0.2H, voltage U=of sensor resistance
7.2V, in the case of exponential functionNormalizing isAnd the exciting current obtained after being reconstructed with signal frequency
Signal.Fig. 9 is the frequency spectrum of exciting current signal, which contains only the odd times times harmonic wave of signal frequency, and Figure 10 is differential interference
The cross-correlation coefficient of signal and exciting current signal.Due to differential interference signal and exciting current signal cross-correlation；So excitation
There is also similar asymmetry for electric current；In order to extract the characteristic quantity of differential interference signal dynamic change, need to interfere differential
Signal carries out pectination bandpass filtering with exciting current signal and retains odd harmonic cancellation even-order harmonic and direct current biasing, to eliminate letter
Number asymmetry.
In the present embodiment, certain data volume is needed (to be reached from signal starting variation since pectination bandpass filtering calculates
Stable state need be more than 100 times signal period), but with 1Hz excitation frequencies go out number from the point of view of, the data volume provided is few, need
Want the time long；Then the signal data that a cycle is only taken in the present embodiment copies 99 groups of data next, respectively such as Figure 11
Shown in Figure 12；The requirement of the characteristic quantity of extraction differential interference signal and exciting current signal can be met in this way.
In the present embodiment, the exciting current signal and differential interference signal when acquisition zeroing, by measuring letter to practical
Differential interference signal in number and exciting current signal carry out pectination bandpass filtering, retain odd harmonic eliminate even-order harmonic with it is straight
Stream biasing, obtains differential interference signal in practical measurement signals, dry according to differential in the actual zero point and practical measurement signals
Signal is disturbed, the true zero signal of practical measurement signals is obtained.
Due to
Differential interferes
Wherein, U is sensor both end voltage, and R is sensor resistance, and L is sensors inductance, and k is constant, and S is effectively to cut
Area, N are that coil pricks number, and μ is magnetic conductivity；
It can constructor：
Since i (t) exciting currents can measure,It is known quantity when zeroing；At that time micro- can be measured when zeroing
Divide interference signal；This moment is known quantity；
Due to U, R can be measured；(formula three) is brought into (formula two) to can be obtained afterwards
Because when sensor resistance R is much larger than internal resistance of source rFor approximate constant；
Therefore K can be acquired by (formula one) in zeroing；
When R is as independent variable, (formula once) is the function of R, and molecule part can be measured by exciting current, then be asked
Denominator size is obtained, denominator is subtractedAfter negate, can obtainThat is differential interference signal；
In the present embodiment, converter measures exciting current size and excitation signal size simultaneously, calculates sensor electricity
Size is hindered, sensor resistance is much larger than the internal resistance of cell+sampling resistor to ensure that U values can be ignored by the influence of R；Since water is
Non-magnetic medium is thereforeIt can ignore；It only needs to eliminate differential and interferes and make after simple smooth filtering to obtain fluid
Signal；
It is variations of the U with R below
Due to internal resistance of cell r ＜ ＜ R so that U1≈U2；
According to differential interference calculation formula
Wherein, U is sensor both end voltage, and R is sensor resistance, and L is sensors inductance, and k is constant, and S is effectively to cut
Area, N are that coil pricks number；It is obtained by senile experiment, the Main Factors for influencing differential interference are U and R, and U comes from battery powered
Power supply, R come from sensor coil resistance, and the two larger other parameters affected by the ambient temperature can be considered constant, therefore micro-
Point interference formula changeable type be
Four formulas are split into two formula；
y1=KU (formula five),
y2=(eRt)k′(formula six), it is seen that formula five is a linear formula, and formula six is an exponential function formula, and due to electricity
Pond internal resistance is much smaller than sensor coil resistance, and two formulas are orthogonal；The compensation that is affected by temperature is interfered to differential when use, it can be with
Formula five and formula six are compensated respectively to realize；
Due to sensor signal
Therefore
V=klv+KR (eRt)k′(formula ten)；
It can be obtained by formula ten, when the internal resistance of cell is much smaller than sensor coil resistance, null offset is only related with R.
Establish Zero Model
It can obtain
Due to t0, t1, R, A are it is known that k' can be acquired as follows；
Above-mentioned is to obtain sensing by being sampled in two different time points with an excitation when returning to zero before calibration
The characteristic quantity k' of device；Be below by equipment running process, due to temperature influence in the case of resistance of sensor changes
Same time point is sampled, and the variable quantity of zero is acquired；
Thus V can be released0'=(1-K') × V0；
To the zero value after being compensated.
It can be quickly obtained actual zero point and differential interference signal by the above method, it is worked as from real fluid signal
Middle removal obtains true zero signal.
The above-described embodiments merely illustrate the principles and effects of the present invention, and is not intended to limit the present invention.It is any ripe
The personage for knowing this technology can all carry out modifications and changes to above-described embodiment without violating the spirit and scope of the present invention.Cause
This, institute is complete without departing from the spirit and technical ideas disclosed in the present invention by those of ordinary skill in the art such as
At all equivalent modifications or change, should by the present invention claim be covered.
Claims (7)
1. a kind of quick zero point compensation method of electromagnetic flow-measurement, which is characterized in that including：
Directly zero state signal is acquired, the offset of signal base line is obtained according to collection result；
Actual zero point is obtained according to the offset of the signal base line；
Practical measurement signals are acquired, and in real time compensate the actual zero point into actual signal, complete quick zero compensation.
2. the quick zero point compensation method of electromagnetic flow-measurement according to claim 1, it is characterised in that：Pre-set use
In the measurement point of acquisition zero state signal different conditions, the letter is obtained according to measured value of the zero state signal within a signal period
The offset of number baseline, and using the offset of the signal base line as linear variable, by the survey in the zero state signal period
Magnitude carries out signal processing, eliminates the offset of actual zero point and the signal base line.
3. the quick zero point compensation method of electromagnetic flow-measurement according to claim 2, which is characterized in that the absolute zero
Point is eliminated in the following way：
(A2-A4)-(A1-A3)
Wherein, it is high level signal, A3 in the zero state signal period that A1, which is the first high-impedance state signal, A2 in the zero state signal period,
For the second high-impedance state signal in the zero state signal period, A4 is the low level signal in the zero state signal period.
4. the quick zero point compensation method of electromagnetic flow-measurement according to claim 2, which is characterized in that at the signal
Reason further include to practical measurement signals directly by analog-to-digital conversion module carry out analog-to-digital conversion, and to the signal after analog-to-digital conversion into
Row low-pass filtering treatment.
5. the quick zero point compensation method of electromagnetic flow-measurement according to claim 4, which is characterized in that when acquisition zeroing
Exciting current signal and differential interference signal, by the differential interference signal and exciting current signal in practical measurement signals
Pectination bandpass filtering is carried out, retains odd harmonic and eliminates even-order harmonic and direct current biasing, it is dry to obtain differential in practical measurement signals
Signal is disturbed, according to differential interference signal in the actual zero point and practical measurement signals, obtains the true zero of practical measurement signals
Point signal.
6. the quick zero point compensation method of electromagnetic flow-measurement according to claim 5, which is characterized in that micro- when to zeroing
When interference signal and exciting current signal being divided to carry out pectination bandpass filtering, the signal data of a cycle is obtained, and to the period
Signal data carry out replicate be used as follow-up data, with meet pectination bandpass filtering calculating data volume.
7. the quick zero point compensation method of electromagnetic flow-measurement according to claim 5, which is characterized in that by reality
After differential interference signal and exciting current signal in measuring signal carry out pectination bandpass filtering, with practical measurement signals frequency pair
The exciting current signal is reconstructed, and obtains the exciting current signal after reconstruct.
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| CN110207768A (en) * | 2019-06-26 | 2019-09-06 | 上海市计量测试技术研究院 | A kind of intelligent electromagnetic flowmeter |
| CN113340383A (en) * | 2020-03-03 | 2021-09-03 | 上海锐铼水务科技有限公司 | Method and system for detecting magnetic field abnormality and compensating error of electromagnetic water meter |
| CN113447099A (en) * | 2021-06-25 | 2021-09-28 | 上海肯特仪表股份有限公司 | Automatic zero correction method for electromagnetic water meter |
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Application publication date: 20181012 |