CN102128652B - Hybrid-frequency excitation electromagnetic flow converter - Google Patents
Hybrid-frequency excitation electromagnetic flow converter Download PDFInfo
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- CN102128652B CN102128652B CN2011100426941A CN201110042694A CN102128652B CN 102128652 B CN102128652 B CN 102128652B CN 2011100426941 A CN2011100426941 A CN 2011100426941A CN 201110042694 A CN201110042694 A CN 201110042694A CN 102128652 B CN102128652 B CN 102128652B
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Abstract
The invention discloses a hybrid-frequency excitation electromagnetic flow converter comprising a processor, a photoelectric isolation circuit, a data constant flow source circuit, an excitation circuit and a hybrid-frequency excitation converting unit, wherein the processor generates a series of square-wave pulse signals to control the hybrid-frequency excitation converting unit, and the hybrid-frequency excitation converting unit generates regular square-wave pulses as excitation signals to realize a data constant flow source supplied to the excitation circuit. Meanwhile, the magnitudes and respectively occupied time signals of two kinds of excitation are determined by the processor through an optimization algorithm according to signals fed back on site, the hybrid-frequency excitation converting unit is controlled by the pulse signals through the photoelectric isolation circuit, and then a hybrid-frequency excitation way with two kinds of excitation appearing alternately and periodically is realized through the data constant flow source circuit. The hybrid-frequency excitation electromagnetic flow converter disclosed by the invention can automatically adjust the proportion of high frequency and low frequency according to a fluid interference condition, has the advantage of rapid response for interference of different noises appearing in fluids, and has lower production and maintenance costs.
Description
Technical field
The present invention relates to the excitation technology of electromagnetic flowmeter, more particularly, relate to a kind of mixing excitation electromagnetic flux converter.
Background technology
Electromagnetic flowmeter is an instrument of measuring the conductive liquid volumetric flow rate according to Faraday's electromagnetic induction law, and it can carry out flow measurement by convection cell under situation such as laminar flow, turbulent flow, pulsating flow and the vibration of generation streamline.As shown in Figure 1: electromagnetic flowmeter is in when work, fluid through the time cutting magnetic line produce faint electric signal, this signal is very faint not only; And various undesired signals have been mixed; The original signal 1 of the noisy sound of their common compositions, original signal 1 is amplified through the preliminary amplifying circuit of differential amplifier 2, obtains sampled signal through high frequency sampling 3 with low-frequency sampling 4 respectively with field circuit 9 then; Sampled signal is passed through high-pass filtering 5 and LPF 6 respectively; Obtain the signal of a high frequency and the signal of a low frequency, come optimization process by CPU after treatment, thereby obtain stable and flow signal 8 accurately.And the measuring accuracy of electromagnetic flowmeter and zero stability and the excitation mode that adopted have much relations, and the excitation mode of electromagnetic flowmeter mainly contains low frequency excitation and two kinds of high frequency excitations at present, and low frequency excitation has stable zero point, but to the noise jamming sensitivity; And the high frequency excitation is on the contrary, and antijamming capability is stronger, but zero point is unstable.So just caused the electromagnetism of single-frequency can only be used under the specific situation.The excitation mode of Electromagnetic Flow is main with low frequency square wave excitation mainly in the prior art; But low frequency square wave excitation is unsatisfactory aspect anti-current moving noise and slurries noise; When carrying out the slurries measurement; Measuring accuracy and zero stability often do not reach customer requirements, and it is bigger to fluctuate in the use, the general relatively poor measuring accuracy that influences of antijamming capability.To this shortcoming, released several kinds of new excitation modes on the market, as: dual-frequency excitation, frequency adjustable square wave excitation and pulse ac excitation etc., but the response speed of its corresponding different noise is slower, and cost is also very high simultaneously.
Summary of the invention
Electromagnetic flowmeter antijamming capability to the employing low frequency square wave excitation that exists in the prior art is generally relatively poor; When carrying out the slurries measurement; Measuring accuracy and zero stability often do not reach the problem of customer requirements; The purpose of this invention is to provide a kind of mixing excitation electromagnetic flux converter, overcome the zero point and the noise jamming problem of common excitation through the mixing excitation mode.
In order to realize the foregoing invention purpose, the technical scheme that the present invention adopts is following:
A kind of mixing excitation electromagnetic flux converter; The output terminal that comprises processor, processor is connected with the input end of photoelectric isolating circuit, the output terminal of photoelectric isolating circuit is connected with the input end of data constant-current source circuit; The output terminal of data constant-current source circuit is connected with the input end of field circuit; Also comprise mixing excitation converting unit; The input end of said mixing excitation converting unit is connected with the output terminal of processor, and the output terminal of mixing excitation converting unit is connected with the input end of data constant-current source circuit.
Said data constant-current source circuit comprises sensor field coil and the sampling resistor that is connected in series with the sensor field coil; The input end of sampling resistor links to each other with the negative input of first amplifier, and the first amplifier anode input end links to each other with the high-frequency impulse control electronic switch of control reference voltage; The output terminal of first amplifier links to each other with the negative input of second amplifier, and the electrode input end of second amplifier links to each other with the supply module of field circuit; Second amplifier out links to each other with the input end of AND circuit; The low frequency rectangular wave pulse signal of control excitation links to each other with another input end of AND circuit; The output terminal of AND circuit is connected with the electronic switch electric bridge through phase inverter, and the electronic switch electric bridge also links to each other with the input end of sensor field coil.
Said mixing excitation converting unit comprises controller, mixing excitation photoelectric isolating circuit and field switch; The input end of said controller is connected with the output terminal of processor; The input end of said mixing excitation photoelectric isolating circuit is connected with the output terminal of controller; The input end of said field switch is connected with the output terminal of mixing excitation photoelectric isolating circuit, and the output terminal of field switch is connected with the input end of data constant-current source circuit.
Said data constant-current source circuit produces low frequency signal and high-frequency signal, and the mode that the cycle of said low frequency signal and the cycle of high-frequency signal adopt low-and high-frequency to replace produces the mixing excitation cycle.
The frequency of said low frequency signal is 6.25Hz.
The frequency of said high-frequency signal is 50Hz.
The periodicity of said low frequency signal is 2.5.
The periodicity of said high-frequency signal is 1.5.
Compared with prior art; Because mixing excitation electromagnetic flux converter of the present invention; Be to produce a series of square-wave pulse signal control mixing excitation converting unit through processor, mixing excitation converting unit produces regular square-wave pulse realizes offering field circuit as excitation signal digital-control constant-flow source; Simultaneously; The flow signal that processor comes according to the scene feedback; Through being the optimized Algorithm of benchmark, confirm the size of two kinds of excitations of high and low frequency and the time signal that takies respectively, through the VF conversion of photoelectric isolating circuit with the least square method; Pulse signal is controlled mixing excitation converting unit thus, realizes that through the digital-control constant-flow source circuit mixing excitation mode periodically alternately appears in two kinds of excitations again.When the impure many interference of detected fluid are big, can improve high fdrequency component; And disturb hour when detected fluid, can reduce high fdrequency component.Through the interference of the detection in software size is the optimized Algorithm of benchmark with the least square method; Big more according to flow rate fluctuation, the frequency of high frequency is high more, and also more principles of shared time; Calculate best frequency size and time ratio, thereby realize the self-control field circuit.Therefore, mixing excitation electromagnetic flux converter of the present invention can be adjusted height frequency shared ratio automatically according to the fluid disturbed condition, has the fast advantage of different noise reaction velocitys that occurs in the convection cell, and production and maintenance cost are lower.
Description of drawings
Fig. 1 is the fundamental diagram of electromagnetic flowmeter in the prior art;
Fig. 2 is the theory diagram of a kind of mixing excitation electromagnetic flux converter of the present invention;
Fig. 3 is the circuit diagram of data constant-current source circuit among Fig. 2;
Fig. 4 is the excitation frequency synoptic diagram of a kind of mixing excitation electromagnetic flux converter of the present invention;
Fig. 5 is the contrast synoptic diagram of the mixing excitation signal of excitation signal of the prior art and the present invention's generation.
Embodiment
Further specify technical scheme of the present invention below in conjunction with accompanying drawing and embodiment.
Embodiment
See also shown in Figure 2: a kind of mixing excitation electromagnetic flux converter of the present invention; Comprise it for example being that the output terminal of the MSP430 processor 11 produced of Texas Instrument, processor 11 is connected with the input end of photoelectric isolating circuit 12, the output terminal of photoelectric isolating circuit 12 is connected with the input end of data constant-current source circuit 13; The output terminal of data constant-current source circuit 13 is connected with the input end of field circuit 14; Also comprise mixing excitation converting unit 15; The input end of mixing excitation converting unit 15 is connected with the output terminal of processor 11, and the output terminal of mixing excitation converting unit 15 is connected with the input end of data constant-current source circuit 13.
Raise the efficiency in order to reduce power consumption, in constant-current source circuit, adopted the data constant-current source circuit 13 that is illustrated in fig. 3 shown below.Similar with simulation adjustment type constant-current source circuit, data constant-current source circuit 13 also needs four transistors to do the electronic switch electric bridge, and basic circuits such as reference voltage source, sampling resistor and comparison amplifier are also arranged.The sensor field coil still is connected between the electric bridge diagonal line that is connected to electronic switch.But, for easy analysis, only use K among the figure
1Represent four end electronic switch electric bridges.Data constant-current source circuit 13 comprises sensor field coil L and the sampling resistor R that is connected in series with sensor field coil L
1, sampling resistor R
1The input end and the first amplifier IC
1Negative input link to each other the first amplifier IC
1The high-frequency impulse control electronic switch K of electrode input end and control reference voltage
2Link to each other; The first amplifier IC
1The output terminal and the second amplifier IC
2Negative input link to each other the second amplifier IC
2Electrode input end link to each other with the supply module of field circuit; The second amplifier IC
2Output terminal and AND circuit IC
3Input end link to each other the low frequency rectangular wave pulse signal and the AND circuit IC of control excitation
3Another input end link to each other AND circuit IC
3Output terminal pass through inverter ic
4With electronic switch electric bridge K
1Connect electronic switch electric bridge K
1Also the input end with sensor field coil L links to each other.Work as switch connection, power supply Ec has electric current I flows through sensor field coil L and sampling resistor R1.Electric current I flows through sensor coil L produces work magnetic field on the one hand, and the conductive fluid flows through sensor produces induction electromotive force, and electric current flows through sampling resistor R1 on the other hand, forms feedback voltage U2 at its two ends.High-frequency impulse control electronic switch K2 is modulated to the output reference pulse voltage U1 in order to the dutycycle n1=t1/T1 of the parameter of digital sensor constant with stable benchmark voltage.Basic pulse voltage U 1 and feedback voltage U2 are added comparison amplifier IC1 simultaneously compare and amplify, obtain output dc voltage U3.Output dc voltage U3 again with a triangular wave (voltage E2) that obtains from the supply module of field circuit that is added in comparison amplifier IC2 in-phase end relatively, the output that obtains is that the parameter dutycycle in order to digital regulated constant current source is the rect.p. of n2=t/T.The square wave pulse of dutycycle n2 gets into AND circuit IC3 simultaneously with the low frequency square wave pulse UA of control excitation; Output is through inverter ic 4 paraphase; Become the interrupted high frequency square wave pulse of low frequency modulations; Go again to control the connection of electronic switch electric bridge K1 and end, so just constituted a closed-loop system.The high frequency square wave pulse of modulation is by sensor field coil L and electric capacity elimination, and the size of current of flows through sensor field coil L is and the relevant low frequency square wave of reference voltage size.Through the value of dutycycle n1=t1/T1 is set, just revise the value of t1 and T1, i.e. the size of digital modifications exciting current.Compare with the constant-current source circuit of analog feedback, the high heating of digital-control constant-flow source efficient is little.This is that the forward voltage that transistor is under the on off state is fallen below 1V because digital-control constant-flow source circuit 13 is operated in pulse condition, and the pulse width during conducting is narrower again, so the power loss gadget can not produce a lot of heats.Utilize the value that changes dutycycle n1 simultaneously, can realize that the digital quantity of constant current size is set, excitation control is connected with single-chip microcomputer, realize the intelligent measure of electromagnetic flowmeter.
Mixing excitation converting unit 15 comprises that complex programmable logic controller 151 is called for short CPLD, mixing excitation photoelectric isolating circuit 152 and field switch 153; The input end of complex programmable logic controller 151 is connected with the output terminal of MSP430 processor 11; The input end of mixing excitation photoelectric isolating circuit 152 is connected with the output terminal of MSP430 controller 11; The input end of field switch 153 is connected with the output terminal of mixing excitation photoelectric isolating circuit 152, and the output terminal of field switch 153 is connected with the input end of data constant-current source circuit 13.The mixing excitation is through the software and hardware generation of combining closely; MSP430 processor 11 produces a series of square-wave pulse signal control complex programmable logic controller CPLD151 through programming; Produce regular square-wave pulse as excitation signal by complex programmable logic controller CPLD151; Be added to data constant-current source circuit 13 through mixing excitation photoelectric isolating circuit 152, realize offering the digital-control constant-flow source of field circuit 14.Simultaneously; The flow signal that MSP430 processor 11 comes according to the scene feedback; Process is the optimized Algorithm of benchmark with the least square method; Confirm the size of two kinds of excitations and the time signal that takies respectively, process mixing excitation photoelectric isolating circuit 152 pulse signal is thus controlled field switch 153, realizes the situation that two kinds of excitations periodically alternately occur through digital-control constant-flow source circuit 13 again.Data constant-current source circuit 13 produces low frequency signal and high-frequency signal, and the mode that the cycle of low frequency signal and the cycle of high-frequency signal adopt low-and high-frequency to replace produces the mixing excitation cycle.This shows that the mixing excitation promptly through the mode of programming, lets processor choose according to the actual conditions intelligence at scene, let the periodic alternate run of excitation and the novel excitation mode that produces of two kinds of different frequencies.If select low frequency 6.25HZ, two kinds of frequencies of high frequency 50HZ alternately occur through both, and in 2.5 cycles of low frequency, in 1.5 cycles of high frequency, the waveform of its excitation frequency is illustrated in fig. 4 shown below so, and wherein horizontal ordinate is time t, and ordinate is amplitude B.Reality result of use under the slurries situation is as shown in Figure 5, and wherein, line A is the flow signal that common excitation measurement is come out, and the flow signal that below line B then detects for the mixing excitation can know that through contrast the signal of line B is highly stable.
Those of ordinary skill in the art will be appreciated that; Above embodiment is used for explaining the object of the invention; And be not with opposing qualification of the present invention; As long as in essential scope of the present invention, all will drop in the scope of claim of the present invention variation, the modification of the above embodiment.
Claims (7)
1. mixing excitation electromagnetic flux converter; The output terminal that comprises processor, processor is connected with the input end of photoelectric isolating circuit, the output terminal of photoelectric isolating circuit is connected with the input end of digital-control constant-flow source circuit; The output terminal of digital-control constant-flow source circuit is connected with the input end of field circuit; It is characterized in that: also comprise mixing excitation converting unit; The input end of said mixing excitation converting unit is connected with the output terminal of processor, and the output terminal of mixing excitation converting unit is connected with the input end of digital-control constant-flow source circuit; Said digital-control constant-flow source circuit comprises sensor field coil and the sampling resistor that is connected in series with the sensor field coil; The input end of sampling resistor links to each other with the negative input of first amplifier, and the first amplifier anode input end links to each other with the high-frequency impulse control electronic switch of control reference voltage; The output terminal of first amplifier links to each other with the negative input of second amplifier, and the electrode input end of second amplifier links to each other with the supply module of field circuit; Second amplifier out links to each other with the input end of AND circuit; The low frequency rectangular wave pulse signal of control excitation links to each other with another input end of AND circuit; The output terminal of AND circuit is connected with the electronic switch electric bridge through phase inverter, and the electronic switch electric bridge also links to each other with the input end of sensor field coil.
2. mixing excitation electromagnetic flux converter according to claim 1; It is characterized in that: said mixing excitation converting unit comprises controller, mixing excitation photoelectric isolating circuit and field switch; The input end of said controller is connected with the output terminal of processor; The input end of said mixing excitation photoelectric isolating circuit is connected with the output terminal of controller; The input end of said field switch is connected with the output terminal of mixing excitation photoelectric isolating circuit, and the output terminal of field switch is connected with the input end of digital-control constant-flow source circuit.
3. mixing excitation electromagnetic flux converter according to claim 1 and 2; It is characterized in that: said digital-control constant-flow source circuit produces low frequency signal and high-frequency signal, and the mode that the cycle of said low frequency signal and the cycle of high-frequency signal adopt low-and high-frequency to replace produces the mixing excitation cycle.
4. mixing excitation electromagnetic flux converter according to claim 3 is characterized in that: the frequency of said low frequency signal is 6.25Hz.
5. mixing excitation electromagnetic flux converter according to claim 3 is characterized in that: the frequency of said high-frequency signal is 50Hz.
6. mixing excitation electromagnetic flux converter according to claim 3 is characterized in that: the periodicity of said low frequency signal is 2.5.
7. mixing excitation electromagnetic flux converter according to claim 3 is characterized in that: the periodicity of said high-frequency signal is 1.5.
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| CN2011100426941A CN102128652B (en) | 2011-02-22 | 2011-02-22 | Hybrid-frequency excitation electromagnetic flow converter |
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| CN2011100426941A CN102128652B (en) | 2011-02-22 | 2011-02-22 | Hybrid-frequency excitation electromagnetic flow converter |
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| CN111174856B (en) * | 2018-11-12 | 2024-04-26 | 杭州为峰智能科技有限公司 | Rotation detection device |
| WO2021087704A1 (en) * | 2019-11-04 | 2021-05-14 | 深圳市大疆创新科技有限公司 | Electromagnetic flowmeter, control method, spraying system, and agricultural unmanned aerial vehicle |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4773274A (en) * | 1987-03-03 | 1988-09-27 | Yokogawa Electric Corporation | Electromagnetic flow meter |
| CN1409093A (en) * | 2001-09-20 | 2003-04-09 | 横河电机株式会社 | Electromagnetic flow meter |
| CN101644591A (en) * | 2009-09-08 | 2010-02-10 | 合肥工业大学 | Mono-dual frequency electromagnetic flowmeter excitation control system based on linear power supply |
| CN101726334A (en) * | 2009-12-23 | 2010-06-09 | 合肥工业大学 | Electromagnetic flow meter excitation control system based on high and low voltage power switching |
| JP2010276470A (en) * | 2009-05-28 | 2010-12-09 | Yokogawa Electric Corp | Electromagnetic flow meter |
-
2011
- 2011-02-22 CN CN2011100426941A patent/CN102128652B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4773274A (en) * | 1987-03-03 | 1988-09-27 | Yokogawa Electric Corporation | Electromagnetic flow meter |
| CN1409093A (en) * | 2001-09-20 | 2003-04-09 | 横河电机株式会社 | Electromagnetic flow meter |
| JP2010276470A (en) * | 2009-05-28 | 2010-12-09 | Yokogawa Electric Corp | Electromagnetic flow meter |
| CN101644591A (en) * | 2009-09-08 | 2010-02-10 | 合肥工业大学 | Mono-dual frequency electromagnetic flowmeter excitation control system based on linear power supply |
| CN101726334A (en) * | 2009-12-23 | 2010-06-09 | 合肥工业大学 | Electromagnetic flow meter excitation control system based on high and low voltage power switching |
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Owner name: ZHEJIANG JINGHUA MEASUREMENT + CONTROL EQUIPMENT C Free format text: FORMER OWNER: SHANGHAI TIANSHI CONTROL SYSTEM CO., LTD. Effective date: 20150217 |
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Effective date of registration: 20150217 Address after: 325000, No. 2, 481, Jinhai Road, Wenzhou Binhai City, Zhejiang Province Patentee after: Zhejiang Jinghua Measurement & Control Equipment Co., Ltd. Address before: 201605 Shanghai Songjiang District Xinbang town forest road No. 199 Patentee before: Shanghai Tianshi Control System Co., Ltd. |