CN107102586B - A kind of coriolis mass flowmeters amplitude control method - Google Patents
A kind of coriolis mass flowmeters amplitude control method Download PDFInfo
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
- G01F1/78—Direct mass flowmeters
- G01F1/80—Direct mass flowmeters operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
- G01F1/84—Coriolis or gyroscopic mass flowmeters
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
- G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P.I., P.I.D.
Abstract
The present invention provides a kind of coriolis mass flowmeters amplitude control methods, it is related to field of fluid measurement, it is sampled by opening vibration signal to flowtube, and subtract each other to obtain difference with preset value, then control amount is constituted by linear combination again and amplitude control is carried out to flowtube, using the pid parameter setting method based on magnitude margin, it calculates one group of optimal control parameter value and optimal parameter setting is realized to closed-loop system, the present invention determines amplitude adjusted objective function by the sampling period in optimization flowtube amplitude-frequency response sensitivity section and raising discretized system, it overcomes due to opening supersaturated amplitude out-of-control phenomenon caused by amplitude output increases in short-term, improve the speed of amplitude response, use the method optimizing amplitude tracking performance of Digital Signal Processing, it ensure that high-precision frequency, phase difference output, the hardware used Resource is less, does not need the design for carrying out complicated kernel circuitry, reduces enterprise's use cost.
Description
Technical field
The present invention relates to field of fluid measurement, especially a kind of control method of coriolis mass flowmeters.
Background technique
Coriolis mass flowmeters (Coriolis Mass Flowmeter, CMF) are high with its measurement accuracy, maintenance at
The advantages of this is low and can be realized measuring multiple parameters, is widely used in the quality stream of the liquid mediums such as petroleum and petrochemical industry, food medicine
Measurement field.It is domestic at present under the situations such as small flow two-phase flow/batch of material stream that field of fluid measurement is often met
There are response speeds for the analog circuit driving CMF mode of use slowly, dynamically track vibrating tube amplitude variation performance difference and gain are defeated
Range is limited out waits shortcomings, and the problem of failing with measurement accuracy decline is controlled so as to cause vibrating flow tube, can not be stablized
Measure liquid mass flow.Authorize Colorado Micro Motion, Inc Chinese patent " vibrating tube process parameter sensor
Generalized model space drive control system " (publication number CN1292083A) proposes a kind of for controlling any quantity driving signal
The drive system of mode ingredient, this method filter feedback transducer output signal using a multichannel modal filter
Wave, then the n single-degree-of-freedom modal response signal obtained after filtering is input in driving channel and motivates flowtube to maintain to shake
It is dynamic.The essence or analog-driven mode of the above method, used driving signal need the driving specially designed by one
Device generates, and acts on flowtube then to maintain tube vibration.Due to the feedback signal of flowtube under the conditions of Small flowrate measurement
Very faint, traditional analog driver is limited by device limitation, small to the measurement range of feedback amplitude, leads to not trace into
The amplitude variations of vibrating tube when small flow make measurement result inaccurate often.Authorize BJ University of Aeronautics & Astronautics's Zheng De intelligence etc.
Chinese patent " all-digital closed-loop system of Coriolis mass flowmeter " (publication number CN101881947A) is adopted on hardware circuit
The closed-loop control of coriolis mass flowmeters is realized with digital device, uses Programmadle logic gate array (Field-
Programmable Gate Array, FPGA) realize digital signal processing circuit, and first in first out is introduced in logic circuits
Buffer Unit component (First Input First Output, FIFO) realizes the resolving and control to amplitude, phase.This method
Deficiency be that the driving of the FPGA described in it closed-loop system needs to remodify in the CMF of the different casts of correspondence and design to meet
It is expected that the index of setting, FPGA kernel digital signal processing circuit will include digital filter, signal detector, phase controlling
Seven parts such as device, amplitude controller, sinusoidal signal generator, FIFO component and clock module, inner core is complicated, uses
Cost is very high.
In conclusion analog circuit driving method amplitude control method traditional used in coriolis mass flowmeters
It is unable to satisfy the measuring accuracy of liquid mass flow under small flow two phase flow/batch of material stream situation, since analog-driven mode exists
Dynamically track vibrating flow tube amplitude changes the poor defect of performance, also easily leads to CMF flowtube failure of oscillation or spends showing for Induced Oscillation
As, and the CMF Digitized Closed Loop control system realized using FPGA hardware circuit then has that system complex, design difficulty are big, use
Problem at high cost can not be suitable for all CMF casts.
Summary of the invention
In order to overcome existing analog-driven flowtube amplitude control method and using the Digitized Closed Loop system of FPGA
The deficiency of control method, the present invention provide a kind of Coriolis mass flowmeter amplitude control method based on digital drive-type, adopt
To DSP28335 processor be core processing unit, by flowtube open vibration signal sample, and with preset
Value subtracts each other to obtain basic deviation value, the difference summation that is then calculated again by the basic deviation, every time and basic deviation it is opposite
Deviation constitutes control amount by linear combination and carries out amplitude control to flowtube, is adjusted using the pid parameter based on magnitude margin
Method determines the target letter of amplitude adjusted according to the sampling period in flowtube amplitude-frequency response sensitivity section and discretized system
Number finally calculates one group of optimal control parameter value and realizes optimal parameter setting to closed-loop system, shakes to reach to flowtube
Dynamic system enters effective control of saturation integral domain, when control amount enters saturation region, only accumulates the negative bias of basic deviation item
Residual quantity, and without increasing the cumulative of integral term, vibrating tube steady-state error, increase rate control precision are eliminated with this.
The present invention solves the technical solution that its technical problem is taken comprising the steps of:
Step 1: opening vibration signal to CMF flowtube carries out analog-to-digital conversion (Analog-to-Digital, AD) sampling, use
Converter samples CMF vibrating flow tube signal and exports its digital value sequence to get to being forced to amplitude data, according to
CMF flowtube 1Hz/1mv drives principle that vibrating flow tube amplitude set value V is arrangeds, the flowtube width of k-th of AD sampling output
Angle value and vibrating flow tube amplitude set value VsDifference indicate that e (k-1) indicates (k-1) a AD sampling output with e (k)
Flowtube range value and vibrating flow tube amplitude set value VsDifference, using difference equation
U (k)=Kp[e(k)+Ki∑e(k)+Kd(e(k)-e(k-1))] (1)
The control amount U (k) of CMF closed loop self oscillatory system controller output is solved, wherein Kp、KiAnd KdRespectively indicate ratio
Example constant, integral constant and derivative constant；
Step 2: oscillograph acquires CMF flowtube pumping signal amplitude, the stream then acquired with converter in step 1
Buret is forced to amplitude data and carries out logistic fit, the relation curve side for obtaining the control amount of driving voltage and being forced between amplitude
Journey, the logistic fit curvilinear equation that will be obtained
Y=0.5177ln (x) -0.4813 (2)
Governing equation is adjusted as amplitude, wherein x is the control amount of driving signal, and y is to be forced to amplitude；
Step 3: the objective function for defining amplitude adjusted is F (Kp, Ki, Kd), objective function F (Kp, Ki, Kd) meet F
(Kp, Ki, Kd)=ε1σ+ε2ts+ε3N, and the weighting coefficient ε of parameter1、ε2、ε3Meet relationship
ε1+ε2+ε3=1, wherein σ is overshoot, tsFor system regulating time, N is flowtube amplitude response threshold range,
Objective function, proportionality constant and integral constant meet following constraint condition:
Guarantee weighting coefficient ε1+ε2+ε3Under conditions of=1, first from proportionality constant KpStart to adjust, then adjusts integral constant
Ki, finally adjust derivative constant Kd, the proportionality constant for meeting formula (3), integral constant and derivative constant are sequentially found, by showing
Wave device observation window monitors the variation of vibrating flow tube amplitude, and parameter specifically adjusts principle are as follows:
When the amplitude oscillation data on oscillograph show that amplitude oscillation frequency is greater than 20 times/second, by proportionality constant KpAdd
0.03, otherwise do not adjust；When the amplitude read in the scale value from oscillograph deviates setting amplitude VsFall velocity value it is big
In 0.5 second, then by integral constant KiSubtract 0.03, does not otherwise adjust；When the difference of flowtube oscillations Amplitude maxima and minimum value
Beyond amplitude response threshold range N, then by derivative constant KdSubtract 0.03, does not otherwise adjust；
According to the above principle and sequence adjustment proportionality constant, integral constant and derivative constant, so that the amplitude wave of flowtube
Dynamic range is lower than 0.2mv；
Step 4: difference e (k), e (k-1), e (k-2) to be substituted into the error increment equation Δ U (k) of PID output control amount
=U (k)-U (k-1), obtains Δ U (k) are as follows:
Δ U (k)=Kp(e(k)-e(k-1))+Kie(k)+Kd(e(k)-2e(k-1)+e(k-2)) (4)
Wherein, e (k-2) indicates the flowtube range value and vibrating flow tube amplitude set of (k-2) a AD sampling output
Value VsDifference bring formula (2) input parameter x into using Δ U (k) as the drive control amount to flowtube, obtain forced oscillation
Width；
The control amount U (k) for calculating current time, judges whether control amount U (k) exceeds amplitude response threshold range N,
N=[Umax, Umin], amplitude response upper bound Umax=Vs+ 0.2, amplitude response lower bound Umin=Vs- 0.2, work as U
(k) when exceeding amplitude response threshold range N, by K in formula (4)i0 implementation anti-saturation integral separation is set, so that flowtube amplitude
Fluctuation range is lower than 0.2mv.
The beneficial effects of the invention are as follows tune ginseng is carried out due to using the pid parameter setting method based on magnitude margin, lead to
The sampling period for crossing optimization flowtube amplitude-frequency response sensitivity section and raising discretized system determines amplitude adjusted objective function.
The constraint condition that objective function, proportionality constant and integral constant meet is solved, then verifies optimal proportionality constant Kp, integral constant
Ki, derivative constant Kd, complete optimal parameter setting.The limit range of drive control amount output is set, is overcome due to opening amplitude
Output supersaturated amplitude out-of-control phenomenon caused by increasing in short-term.Small flow is unable to satisfy compared to conventional analog circuits driving method
The control precision of liquid quality stream discharge amplitude, changes insensitive disadvantage to flowtube amplitude under two phase flow/batch of material stream situation, this
The method of invention improves the speed of amplitude response, using the method optimizing amplitude tracking performance of Digital Signal Processing, so that
Flowtube can maintain stable amplitude with the actuation techniques index of 1Hz/1mv, ensure that high-precision frequency, phase difference output.Phase
Than the CMF Digitized Closed Loop control system that FPGA hardware circuit is realized, the hardware resource that this method uses is less, does not need to carry out
The design of complicated kernel circuitry, reduces enterprise's use cost.
Detailed description of the invention
Fig. 1 is the CMF flowtube system structure diagram of industrial application, wherein 1- parallel U-shaped measurement pipe, 2- sensing
Device A, 3- sensor B, 4- drive circuit assembly.
Fig. 2 is full digital coriolis mass flowmeters driving system structure schematic diagram of the invention, and wherein Vout is
Digital-to-analogue multiplier carries out the output of amplitude adjustment as a result, D+ is to DDS initial excitation amount or sensors A, the road B signal amplitude
Vout passes through the drive control amount that power amplification circuit obtains, and CH1, CH2 are that oscillograph monitors input port, the road INA, INB point
Not Wei sensors A, sensor B output vibrating tube vibration signal.
Fig. 3 is PID controller structural block diagram of the invention.
Fig. 4 is that flowtube of the invention drives-be forced to amplitude logistic fit curve graph.
Fig. 5 is system flow chart of the invention.
Specific embodiment
Present invention will be further explained below with reference to the attached drawings and examples.
Step 1: opening vibration signal to CMF flowtube carries out analog-to-digital conversion (Analog-to-Digital, AD) sampling, use
Converter samples CMF vibrating flow tube signal and exports its digital value sequence to get to being forced to amplitude data, according to
CMF flowtube 1Hz/1mv drives principle that vibrating flow tube amplitude set value V is arrangeds, the flowtube width of k-th of AD sampling output
Angle value and vibrating flow tube amplitude set value VsDifference indicate that e (k-1) indicates (k-1) a AD sampling output with e (k)
Flowtube range value and vibrating flow tube amplitude set value VsDifference, using difference equation
U (k)=Kp[e(k)+Ki∑e(k)+Kd(e(k)-e(k-1))] (1)
The control amount U (k) of CMF closed loop self oscillatory system controller output is solved, wherein Kp、KiAnd KdRespectively indicate ratio
Example constant, integral constant and derivative constant；
Step 2: oscillograph acquires CMF flowtube pumping signal amplitude, the stream then acquired with converter in step 1
Buret is forced to amplitude data and carries out logistic fit, the relation curve side for obtaining the control amount of driving voltage and being forced between amplitude
Journey, the logistic fit curvilinear equation that will be obtained
Y=0.5177ln (x) -0.4813 (2)
Governing equation is adjusted as amplitude, wherein x is the control amount of driving signal, and y is to be forced to amplitude；
Step 3: the objective function for defining amplitude adjusted is F (Kp, Ki, Kd), objective function F (Kp, Ki, Kd) meet F
(Kp, Ki, Kd)=ε1σ+ε2ts+ε3N, and the weighting coefficient ε of parameter1、ε2、ε3Meet relationship
ε1+ε2+ε3=1, wherein σ is overshoot, tsFor system regulating time, N is flowtube amplitude response threshold range,
Objective function, proportionality constant and integral constant meet following constraint condition:
Guarantee weighting coefficient ε1+ε2+ε3Under conditions of=1, first from proportionality constant KpStart to adjust, then adjusts integral constant
Ki, finally adjust derivative constant Kd, the proportionality constant for meeting formula (3), integral constant and derivative constant are sequentially found, by showing
Wave device observation window monitors the variation of vibrating flow tube amplitude, and parameter specifically adjusts principle are as follows:
When the amplitude oscillation data on oscillograph show that amplitude oscillation frequency is greater than 20 times/second, by proportionality constant KpAdd
0.03, otherwise do not adjust；When the amplitude read in the scale value from oscillograph deviates setting amplitude VsFall velocity value it is big
In 0.5 second, then by integral constant KiSubtract 0.03, does not otherwise adjust；When the difference of flowtube oscillations Amplitude maxima and minimum value
Beyond amplitude response threshold range N, then by derivative constant KdSubtract 0.03, does not otherwise adjust；
According to the above principle and sequence adjustment PID proportionality constant, integral constant and derivative constant, so that the amplitude of flowtube
Fluctuation range is lower than 0.2mv；
Step 4: difference e (k), e (k-1), e (k-2) to be substituted into the error increment equation Δ U (k) of PID output control amount
=U (k)-U (k-1), obtains Δ U (k) are as follows:
Δ U (k)=Kp(e(k)-e(k-1))+Kie(k)+Kd(e(k)-2e(k-1)+e(k-2)) (4)
Wherein, e (k-2) indicates the flowtube range value and vibrating flow tube amplitude set of (k-2) a AD sampling output
Value VsDifference bring formula (2) input parameter x into using Δ U (k) as the drive control amount to flowtube, obtain forced oscillation
Width；
The control amount U (k) for calculating current time judges whether control amount U (k) exceeds amplitude response threshold range N,
N=[Umax, Umin], amplitude response upper bound Umax=Vs+ 0.2, amplitude response lower bound Umin=Vs- 0.2, if U
(k) > Umax accumulates negative bias residual quantity, and the correspondence control amount U (k) of Δ U (k) < 0 is all added, if U (k) < Umin, accumulation
The correspondence control amount U (k) of Δ U (k) > 0 is all added by positively biased residual quantity, i.e., when U (k) exceeds amplitude response threshold range N,
By K in formula (4)i0 implementation anti-saturation integral separation is set, the final result of amplitude control is so that maintaining flowtube amplitude fluctuations
Range is lower than 0.2mv.
As shown in Figure 1, the CMF flowtube system core component industrially applied include: two parallel U-shaped flowtubes,
Vibration signal picks up sensors A, B and driving assembly etc..The present invention uses the processing list using DSP28335 processor as core
Member, other the peripheral auxiliary functional circuit modules being related to are as shown in Figure 2, it can be seen that including Direct Digital Frequency Synthesizers
(Direct Digital Synthesizer, DDS), electronic switch, digital-to-analogue multiplier (Multiplying Digital to
Analog Converter, MDAC), power amplification circuit, signal condition amplifying circuit etc., the wherein sensors A output road INA letter
Number, sensor B exports the road INB signal.
The present invention provides a kind of Coriolis mass flowmeter amplitude control method based on digital driving method, this method meter
Obtained control amount is output to drive circuit assembly shown in Fig. 1, so that two parallel U-shaped flowtubes keep stable vibration width
Degree.Key is that an electronic switch of this method setting controls keyword in Fig. 2, is cut by changing Key value progress driving method
It changes: if Key=0, by the starting flowtube work of DDS drive module；If Key=1, driven by right side feedback signal INA/INB
System constitutes a closed loop autonomous system and generates self-oscillation, and the amplitude control method provided through the invention is controlled
System.Vout is that digital-to-analogue multiplier carries out the defeated of amplitude adjustment to DDS initial excitation amount or sensors A, the road B signal amplitude in Fig. 2
Result out；D+ is the drive control amount that Vout passes through that power amplification circuit obtains, which is output to driving group shown in FIG. 1
Part maintains flowtube stable vibration.CH1, CH2 are that oscillograph monitors input port in Fig. 2, for monitoring the work of vibrational system
Make state；The road INA, INB is the vibrating tube vibration signal of sensors A shown in FIG. 1, sensor B output.
Specific implementation of the invention are as follows:
PID controller structural block diagram shown in Fig. 3, vibrational system time-domain expression is written as
Wherein T is system communication cycle, TdFor response delay
Time, at the kth T moment, deviation e (k)=Rin (k)-Rout (k), wherein Rin (k) is the flowtube amplitude of AD sampling output
Value, Rout (k) are vibrating flow tube amplitude set value, error accumulation ∑ e (k), error differentialAbove-mentioned CMF is shaken
Movable model time-domain expression sliding-model control is
U (k)=Kp[e(k)+Ki∑e(k)+Kd(e (k)-e (k-1))], CMF closed loop self-excitation is replaced with this difference equation
The continuous differential equation of oscillatory system is convenient for doing subsequent processing, in kth T previous moment (k-1) T,
U (k-1)=Kp[e(k-1)+Ki∑e(j)+Kd(e (k-1)-e (k-2))], the increment of kT and two moment of (k-1) T
It is then Δ U (k)=Kp(e(k)-e(k-1))+Kie(k)+Kd(e(k)-2e(k-1)+e(k-2))。
The objective function for defining amplitude adjusted is F (Kp, Ki, Kd)=ε1σ+ε2ts+ε3N, wherein σ is overshoot, tsTo be
System regulating time, N are flowtube amplitude response threshold range, Kp、Ki、KdThe respectively proportionality constant of system, integral constant, micro-
Divide constant, makes objective function parameters weighting coefficient ε1、ε2、ε3Meet ε1+ε2+ε3=1, and objective function, KpAnd KiBelow meeting about
Beam condition:
Change each weighting coefficient ε1、ε2、ε3Size, tested referring to shown in Fig. 4 obtained flowtube drive-be forced to amplitude
The right result of logistic fit adjusts drive signal amplitude, first from proportionality constant KpStart to adjust, then adjusts integral constant Ki, finally adjust
Save derivative constant Kd, the Optimal Control constant for meeting above-mentioned constraint condition is sequentially found, vibrating flow tube width is monitored by oscillography
The variation of degree, when the amplitude oscillation data on oscillograph show that amplitude oscillation frequency is greater than 20 times/second, by proportionality constant KpAdd
0.03, otherwise do not adjust；When the amplitude read in the scale value from oscillograph deviates setting amplitude VsFall velocity value it is big
In 0.5 second, then by integral constant KiSubtract 0.03, does not otherwise adjust；When the difference of flowtube oscillations Amplitude maxima and minimum value
Beyond amplitude response threshold range N, then by derivative constant KdSubtract 0.03, does not otherwise adjust.
The present invention makes flowtube remain steady to control error increment Δ U (k) as the driving excitation control amount to flowtube
Determine resonance state, calculate the control amount U (k) at current time, judges whether control amount U (k) exceeds amplitude response threshold range N,
N=[Umax, Umin], amplitude response upper bound Umax=Vs+ 0.2, amplitude response lower bound Umin=Vs-0.2.When U (k) exceeds width
Spend response lag range N when, by formula (4) in Ki0 implementation anti-saturation integral separation is set, prevents flowtube from occurring in a short time
Vibrational system exports the case where relatively large deviation and causes system amplitude that will persistently increase and generated Induced Oscillation.
Flow chart of the invention is as shown in figure 5, drive policy setting flowtube need according to CMF flowtube 1Hz/1mv first
Then Oscillation Amplitude value to be achieved carries out parameter tuning to the proportionality constant of PID, integral constant, derivative constant, uses setting value
Actual vibration range value is subtracted, when the absolute value of the value is greater than 0.2mv, integral separation calculates the error increment of control amount simultaneously
Vibration is maintained with this to control flowtube；When the absolute value of the value is less than 0.2mv, directly the error increment of control amount is calculated simultaneously
Stable vibration is maintained to control flowtube with this, vibrating flow tube amplitude adjusts knot when setting in Oscillation Amplitude threshold range
Otherwise return is started to readjust by beam.
Claims (1)
1. a kind of coriolis mass flowmeters amplitude control method, it is characterised in that include the following steps:
Step 1: opening vibration signal to CMF flowtube carries out analog-to-digital conversion sampling, CMF vibrating flow tube is believed using converter
It number is sampled and exports its digital value sequence to get to amplitude data is forced to, principle is driven according to CMF flowtube 1Hz/1mv
Vibrating flow tube amplitude set value V is sets, the flowtube range value and vibrating flow tube amplitude set of k-th of AD sampling output
Value VsDifference indicate that e (k-1) indicates the flowtube range value and vibrating flow tube of (k-1) a AD sampling output with e (k)
Amplitude set value VsDifference, using difference equation
U (k)=Kp[e(k)+Ki∑e(k)+Kd(e(k)-e(k-1))] (1)
The control amount U (k) of CMF closed loop self oscillatory system controller output is solved, wherein Kp、KiAnd KdIt is normal to respectively indicate ratio
Number, integral constant and derivative constant；
Step 2: oscillograph acquires CMF flowtube pumping signal amplitude, the flowtube then acquired with converter in step 1
It is forced to amplitude data and carries out logistic fit, the relation curve equation for obtaining the control amount of driving voltage and being forced between amplitude will
Obtained logistic fit curvilinear equation
Y=0.5177ln (x) -0.4813 (2)
Governing equation is adjusted as amplitude, wherein x is the control amount of driving signal, and y is to be forced to amplitude；
Step 3: the objective function for defining amplitude adjusted is F (Kp, Ki, Kd), objective function F (Kp, Ki, Kd) meet F (Kp, Ki,
Kd)=ε1σ+ε2ts+ε3N, and the weighting coefficient ε of parameter1、ε2、ε3Meet relationship
ε1+ε2+ε3=1, wherein σ is overshoot, tsFor system regulating time, N is flowtube amplitude response threshold range, target letter
Number, proportionality constant and integral constant meet following constraint condition:
Guarantee weighting coefficient ε1+ε2+ε3Under conditions of=1, first from proportionality constant KpStart to adjust, then adjusts integral constant Ki, most
Derivative constant K is adjusted afterwardsd, the proportionality constant for meeting formula (3), integral constant and derivative constant are sequentially found, oscillograph is passed through
Observation window monitors the variation of vibrating flow tube amplitude, and parameter specifically adjusts principle are as follows:
When the amplitude oscillation data on oscillograph show that amplitude oscillation frequency is greater than 20 times/second, by proportionality constant KpAdd 0.03, it is no
It does not adjust then；When the amplitude read in the scale value from oscillograph deviates setting amplitude VsFall velocity value be greater than 0.5 second,
Then by integral constant KiSubtract 0.03, does not otherwise adjust；When the difference of flowtube oscillations Amplitude maxima and minimum value exceeds amplitude
Response lag range N, then by derivative constant KdSubtract 0.03, does not otherwise adjust；
According to the above principle and sequence adjustment proportionality constant, integral constant and derivative constant, so that the amplitude fluctuations model of flowtube
It encloses lower than 0.2mv；
Step 4: difference e (k), e (k-1), e (k-2) to be substituted into error increment equation Δ U (k)=U of PID output control amount
(k)-U (k-1), obtains Δ U (k) are as follows:
Δ U (k)=Kp(e(k)-e(k-1))+Kie(k)+Kd(e(k)-2e(k-1)+e(k-2)) (4)
Wherein, e (k-2) indicates the flowtube range value and vibrating flow tube amplitude set value V of (k-2) a AD sampling outputs's
Difference brings formula (2) input parameter x into, obtains being forced to amplitude using Δ U (k) as the drive control amount to flowtube；
Whether the control amount U (k) for calculating current time judges control amount U (k) beyond amplitude response threshold range N, N=
[Umax, Umin], amplitude response upper bound Umax=Vs+ 0.2, amplitude response lower bound Umin=Vs- 0.2, when U (k) is rung beyond amplitude
When answering threshold range N, by K in formula (4)i0 implementation anti-saturation integral separation is set, so that flowtube amplitude fluctuations range is lower than
0.2mv。
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| CN108811058A (en) * | 2018-05-10 | 2018-11-13 | 浙江八方电信有限公司 | A kind of algorithm for being applied to mobile room and dividing power adjustment |
| CN110095165B (en) * | 2019-04-17 | 2020-08-14 | 中国石油化工股份有限公司 | Vibration control method of Coriolis mass flowmeter for measuring multiphase flow |
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| US4884441A (en) * | 1988-05-11 | 1989-12-05 | Lew Hyok S | Variable capacity flowmeter |
| JP3132628B2 (en) * | 1994-07-21 | 2001-02-05 | 富士電機株式会社 | Coriolis mass flowmeter |
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