CN109612540A - A kind of compensation flow-measuring method of high precision temp frequency - Google Patents
A kind of compensation flow-measuring method of high precision temp frequency Download PDFInfo
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- CN109612540A CN109612540A CN201910005244.1A CN201910005244A CN109612540A CN 109612540 A CN109612540 A CN 109612540A CN 201910005244 A CN201910005244 A CN 201910005244A CN 109612540 A CN109612540 A CN 109612540A
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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
- G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
- G01F1/58—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects by electromagnetic flowmeters
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Abstract
A kind of compensation flow-measuring method of high precision temp frequency, is related to a kind of flow measurement technology, in order to solve the problems, such as that existing field special vehicle refrigerating channel flow-measuring method is inaccurate.Measurement method of the invention is the accurate measurement method realized by the intelligent turbine flow transducer combination detected fluid temperature signal of DSP to detected fluid flow；Flow signal processing unit is used for the amplification of detected fluid flow signal compared with；Processes temperature signal unit is used to be converted to detected fluid temperature signal electric signal, and after amplification, generates temperature compensation signal；DSP is used to calculate the preliminary data of detected fluid flow using the amount of cycles of square-wave signal in the unit time, is modified in conjunction with preliminary data of the temperature compensation signal to detected fluid flow, the final precise information for generating detected fluid flow；CAN bus communication unit with special purpose vehicle for communicating.Measurement accuracy height is had the beneficial effect that, suitable for the precise measurement to field special vehicle refrigerating channel flow.
Description
Technical field
The present invention relates to a kind of flow measurement technologies.
Background technique
Intelligent flow measurement is particularly important in the special vehicle of field, by field special vehicle refrigerating channel flow number
According to occupant can just make accurate judgement to field special vehicle working condition；And operating condition locating for the special vehicle of field
Rather harsh, it is desirable that used flow sensor not only measures accurately, and has small in size, moisture-proof, antidetonation, operating temperature
Wide feature；And the case that flow sensor is applied under extreme conditions is relatively fewer；With the development of science and technology, it would be highly desirable to grind
Produce a kind of new field special vehicle refrigerating channel flow-measuring method.
Summary of the invention
The purpose of the present invention is to solve existing field special vehicle refrigerating channel flow-measuring methods inaccurately to ask
Topic proposes a kind of compensation flow-measuring method of high precision temp frequency.
The compensation flow-measuring method of a kind of high precision temp frequency of the present invention are as follows: pass through the intelligent turbine flow of DSP
Sensor combination detected fluid temperature signal realizes the accurate measurement method to detected fluid flow；
The intelligent turbine flow transducer of the DSP includes flow signal processing unit, DSP, processes temperature signal unit
With CAN bus communication unit；
After the flow signal processing unit is used to amplify detected fluid flow signal compared with, square-wave signal is generated；
The processes temperature signal unit is used to detected fluid temperature signal being converted to electric signal, and by amplification with
Afterwards, temperature compensation signal is generated；
Square-wave signal and processes temperature signal unit of the DSP for receiving the generation of flow signal processing unit generate
Temperature compensation signal, and the preliminary data of detected fluid flow is calculated using the amount of cycles of square-wave signal in the unit time,
It is modified in conjunction with preliminary data of the temperature compensation signal to detected fluid flow, it is final to generate the accurate of detected fluid flow
Data；
The CAN bus communication unit is used to the detected fluid flow precise information that DSP2 is generated being sent to special purpose vehicle
Communication system.
The beneficial effects of the invention are as follows the intelligent turbine flow transducers of DSP to use high accuracy frequency measurement technology, measurement result
Accurately, the intelligent turbine flow transducer of DSP can adapt to the operating condition of rather harsh locating for the special vehicle of field；And
And it is mended according to the error that intelligent turbine flow transducer measurement fluid flow of the detected fluid temperature signal to DSP generates
Amendment is repaid, so that measurement method is more accurate.
A kind of compensation flow-measuring method of high precision temp frequency of the present invention is suitable for freezing to field special vehicle
The precise measurement of channel capacity.
Detailed description of the invention
Fig. 1 is a kind of functional block diagram of the compensation flow-measuring method of high precision temp frequency described in specific embodiment one；
Fig. 2 is high accuracy frequency measurement technology analysis diagram in specific embodiment six.
Specific embodiment
Specific embodiment 1: embodiment is described with reference to Fig. 1, a kind of high precision temp frequency benefit described in present embodiment
Repay formula flow-measuring method are as follows: realize to tested by the intelligent turbine flow transducer combination detected fluid temperature signal of DSP
The accurate measurement method of fluid flow；
The intelligent turbine flow transducer of the DSP includes flow signal processing unit 1, DSP2, processes temperature signal list
Member 3 and CAN bus communication unit 4；
After the flow signal processing unit 1 is used to amplify detected fluid flow signal compared with, square-wave signal is generated；
The processes temperature signal unit 3 is used to detected fluid temperature signal being converted to electric signal, and by amplification with
Afterwards, temperature compensation signal is generated；
The DSP2 is used to receive square-wave signal and the life of processes temperature signal unit 3 of the generation of flow signal processing unit 1
At temperature compensation signal, and calculate using the amount of cycles of square-wave signal in the unit time the first step number of detected fluid flow
According to, it is modified in conjunction with preliminary data of the temperature compensation signal to detected fluid flow, final generation detected fluid flow
Precise information；
The CAN bus communication unit 4 is used to the detected fluid flow precise information that DSP2 is generated being sent to special purpose vehicle
Communication system.
In the present embodiment, the intelligent turbine flow transducer of DSP selects high temperature resistant component, it is ensured that product can be long-term
It is worked normally under the conditions of -20 DEG C~+120 DEG C；
CAN bus communication unit 4 is with the communication system communication of the frequency of 10Hz and field special vehicle.
Specific embodiment 2: present embodiment is compensation to a kind of frequency of high precision temp described in specific embodiment one
Flow-measuring method, in the present embodiment, the flow signal processing unit 1 are put including turbine, spiral case, air deflector, No.1
Big circuit and comparison circuit；
The inner wall of the spiral case is equipped with magnetoelectric induction coil；
The turbine is arranged inside spiral case,
After detected fluid passes through air deflector, impulse turbine makes the magnetoelectric induction coil of turbine circumgyration incision spiral case inner wall, magnetic
The variation of electric induction wire loop magnetic resistance generating period generates and tested so that magnetoelectric induction coil flux amount changes
The directly proportional pulse signal of fluid flow size, the pulse signal is after the amplification of No.1 amplifying circuit, using more electric
Road generates square-wave signal.
Flow signal processing unit 1 is made of high-temperature material in the present embodiment, and internal casting glue selects heatproof 200
DEG C or more epoxide-resin glue；Spiral case is made of stainless steel material, meets operating temperature and mechanical environment requirement.
In the present embodiment, turbine includes turbine wheel shaft, bearing and turbo blade；Turbo blade cuts magnetoelectric induction coil
Generated pulse signal is very faint, after the amplification of No.1 amplifying circuit, after comparison circuit Shape correction, finally
The square-wave signal that amplitude is about 3V is generated, DSP2 is sent into and carries out frequency signal acquisition；Detected fluid passes through air deflector impulse turbine
Blade, generated rotating torque make turbine overcome mechanical friction resistance square and flow resistance square and rotate, the turbine leaf of rotation
Piece constantly cuts the magnetoelectric induction coil outside tube wall, therefore induction coil circuit magnetic resistance also periodically changes, and makes to pass through line
The magnetic flux of circle changes, and generates the pulse signal directly proportional to uninterrupted.
The differential equation of motion of the intelligent turbine flow transducer of DSP are as follows:
In formula: J is the rotary inertia of turbine；ω is the angular velocity of rotation of turbine；TrIt is fluid to the pushing torque of blade；
TrmMechanical friction resistance square between turbine wheel shaft and bearing；TrfIt is fluid to the moment of resistance of turbine；TreFor electromagnetic detector pair
The electromagnetic resistance square of turbine.Under normal conditions, electromagnetic resistance square TreSmaller, influence can be ignored；In normal running conditions
Under, turbine is rotated with stable angular velocity omega；After flow is greater than initial-flow value, mechanical resistance square TrmInfluence can neglect
Slightly；The principal element for influencing the intelligent turbine flow transducer flow characteristic of DSP is fluid resistance square Trf, i.e.,
The differential equation of motion obtained under steady working condition is
Tr-Trf=0 (3)
Wherein, pushing torque TrFor
In formula: r is the mean radius of turbo blade；ρ is the density of detected fluid；qvFor the volume flow of detected fluid；F
For the actual internal area of sensor；θ is the angle of turbo blade and axis.
General fluid is in turbulence state, at this time fluid flow resistance square TrfFor
In formula: C is proportionality constant；
The instrument coefficient of the intelligent turbine flow transducer of DSP usually passes through flow standard device experimental calibration and obtains, by
Theoretical equation can not calculate instrument coefficient or the instrument coefficient error of calculating is larger；Instrument obtained by the theoretical analysis and experimental verification
The calculation equation of coefficient:
Wherein, K is instrument coefficient, qvFor the volume flow of fluid, f is pulse frequency；
Wherein, N is the blade quantity of turbine.
Formula (4)~(7) are substituted into formula (3), arrangement can obtain:
By formula (8) it is found that under turbulence state, volume instrument COEFFICIENT K and sensor structure relating to parameters, with flow
qvAnd the physical characteristic parameter (viscosity, Media density etc.) of fluid is unrelated, can be approximately a constant.
In the present embodiment, the operating temperature of the intelligent turbine flow transducer of DSP is -20 DEG C~120 DEG C, output essence
Degree is 5 ‰；In total temperature section, full flow section, the intelligent turbine flow transducer of real liquid calibration DSP is exported as a result, right
Difference between the result and normal data compensates, and is most common compensation method；This method has compensation precision high
Advantage, disadvantage is predominantly cumbersome, and the device is complicated, is not easy practical operation.
It is influenced by fluid temperature (F.T.), sensor internal size changes；The instrument coefficient of turbine flow transducer is produced
It is raw to influence；Its correction factor are as follows:
In formula: α is the sensor air deflector material coefficient of expansion；β is the turbine material coefficient of expansion in sensor；Δ t is work
Make temperature and calibration temperature difference.
Volume instrument coefficient at t DEG C of operating temperature is
Kt=K0K1 (10)
In formula: K0To demarcate volume instrument coefficient when temperature；
The relational expression of fluid density and temperature is
ρt=ρt0-γ(t-t0) (11)
In formula: ρtFluid density when for temperature being t DEG C；ρt0To demarcate fluid density when temperature；γ is fluid density
Temperature coefficient；T is the actual temperature of fluid.
The fluid of certain mass, density change with the variation of temperature, and volume will also change correspondingly；Only measure body
Product flow necessarily introduces large error, will be more reasonable using mass flow measurement；
Define turbine flow transducer quality instrument coefficient be
In formula: qmFor the mass flow of fluid；The absolute change amount of quality instrument coefficient is
ΔKm=Km,t-Km,t0 (13)
In formula: Δ KmFor the absolute change amount of quality instrument coefficient；Km,tWhen for temperature being t DEG C, the quality instrument of sensor
Coefficient；Km,t0When to demarcate temperature, the quality instrument coefficient of sensor；
Formula (11), (12) are substituted into formula (13) and are arranged
In formula: D is proportionality coefficient,
It, can be by under Current Temperatures by formula (14) it is found that in the case where being predicted each temperature lower density of fluid
The density and the density relationship at a temperature of calibration of density fluid, modifying factor temperature change cause the flow error of fluid.
By formula (10) and formula (14), can obtain:
Both:
Wherein, Kv,tFor revised volume instrument coefficient, A is proportionality coefficient；It can compensate for drawing because of temperature by formula (16)
The trueness error of the turbine flow transducer risen.
Instrument coefficient K is generally with the average instrument coefficient in use scopeIt indicates, i.e.,
Wherein, KmaxFor the instrument coefficient in range of flow when maximum stream flow, KminFor in range of flow when minimum discharge
Instrument coefficient；
Within the scope of measurable flow amount, instrument coefficient K is not constant or linear line, according to average instrument coefficientWhirlpool
There certainly will be difference between wheel flow sensor output valve and actual value.The method that gamut piece-wise linearization can be used, as far as possible
Reduce the output difference.
In the use scope of turbine flow transducer, if the characteristic curve at a temperature of calibration is divided into stem portion, according to
According to the difference for the pulse frequency that induction coil generates, the K value in corresponding segment is chosen respectively, substitutes into formula (16), reaches reduction
The purpose of output error.By characteristic curve it is found that within the scope of measurable flow amount, curve is divided into linear zone and minimum discharge is non-linear
Area's two parts；Since minimum discharge inelastic region changes greatly, therefore the segmentation in the part is closeer, and the segmentation of linear zone is dredged.
While guaranteeing computational accuracy, the processing speed of program is improved.
Specific embodiment 3: present embodiment is compensation to a kind of frequency of high precision temp described in specific embodiment two
Flow-measuring method, in the present embodiment, the processes temperature signal unit 3 include platinum resistance temperature probe and No. two amplifications
Circuit；
The opening of the platinum resistance temperature probe through air deflector, is placed in detected fluid；
The electric signal input end of No. two amplifying circuits is connected with the electrical signal that platinum resistance temperature is popped one's head in, and No. two
The output end of amplifying circuit is the temperature compensation signal output end of processes temperature signal unit 3.
In the present embodiment, processes temperature signal unit 3 is used to measure the temperature data of fluid in air deflector, and temperature is surveyed
Amount by the way of Wheatstone bridge, pop one's head in through air deflector by platinum resistance temperature probe model PT1000, platinum resistance temperature
Opening, is placed in detected fluid, when the resistance value of platinum resistance changes because of temperature, potential difference is generated at the both ends of electric bridge, by putting
After big processing of circuit, it is sent into DSP2 and is acquired.The temperature range of processes temperature signal unit 3 is -50 DEG C~130 DEG C, precision
It is 0.5 DEG C, the voltage range of output is 0.1V~3V；ADC is set as subsequent samples mode, using in SEQ1 sequencer
ADCINA0 is as acquisition channel, and DSP2 is internally integrated 12 ADC, and sampling precision is lower, is directly counted using the data that ADC is acquired
Fluid operator temperature error is larger, therefore look-up table is used to calculate fluid temperature (F.T.).
Specific embodiment 4: present embodiment is compensation to a kind of frequency of high precision temp described in specific embodiment three
Reversed Schmidt trigger is arranged in the present embodiment in flow-measuring method in the DSP2；
The square-wave signal that the reversed Schmidt trigger is used to generate flow signal processing unit 1 rectifies.
In the present embodiment, the receiving model of DSP2 is exceeded to the amplitude that Schmidt trigger can be avoided square-wave signal
It encloses, while standardizes square-wave signal more.
In the present embodiment, the model of DSP2 are as follows: TMS320F2812；The integrated enhanced CAN control of TMS320F2812
Device, sensor need not additional CAN controller realization CAN bus underlying protocols.SN65HVD230Q is used to receive and dispatch as CAN bus
Device, it is possible to increase communication distance improves moment anti-interference ability, protects bus, reduces radio frequency interference (RFI), realizes thermal protection etc..
Specific embodiment 5: present embodiment is to a kind of high-precision described in specific embodiment one, two, three or four
The warm compensation flow-measuring method of frequency, in the present embodiment, the intelligent turbine flow transducer of the DSP further include that power supply becomes
Change circuit 5；
The power converting circuit 5 is for being respectively flow signal processing unit 1, DSP2 and processes temperature signal unit 3
Power supply.
Specific embodiment 6: embodiment is described with reference to Fig. 2, present embodiment is to described in specific embodiment one
A kind of compensation flow-measuring method of high precision temp frequency, in the present embodiment, flow signal processing unit 1 uses " middle boundary
Frequency " algorithm carries out traffic frequency acquisition to detected fluid flow signal.
In the present embodiment, " middle boundary's frequency " algorithm is one of high accuracy frequency measurement algorithm, high accuracy frequency measurement algorithm
It is the method for guaranteeing the intelligent turbine flow transducer of DSP and realizing high-acruracy survey precision.
In order to guarantee frequency collection precision, in conjunction with the characteristics of Measuring Frequency Method and cycle test method, carried out using " middle boundary's frequency " algorithm
Traffic frequency acquisition, is analyzed by abundant experimental results, finds out " middle boundary's Frequency point f0", f0Cycle test method, f are used below0With
It is upper to use Measuring Frequency Method, while interference is sealed in using the filtering algorithms such as average filter and recursion smothing filtering removal signal, in this way may be used
To effectively improve frequency measurement accuracy, while high-speed data acquisition and operation are carried out using digital processing unit on hardware, after optimization
Frequency Measurement Algorithm be the real-time for not only having measurement, largely improve measurement accuracy, precision up to 0.05 ‰,
Solves the contradiction in the prior art between the real-time and accuracy of turbine flow signal measurement.
Claims (6)
1. a kind of compensation flow-measuring method of high precision temp frequency, which is characterized in that the measurement method are as follows: pass through the intelligence of DSP
Turbine flow transducer combination detected fluid temperature signal realizes the accurate measurement method to detected fluid flow；
The intelligent turbine flow transducer of the DSP includes flow signal processing unit (1), DSP (2), processes temperature signal list
First (3) and CAN bus communication unit (4)；
After the flow signal processing unit (1) is used to amplify detected fluid flow signal compared with, square-wave signal is generated；
The processes temperature signal unit (3) is used to be converted to detected fluid temperature signal electric signal, and after amplification,
Generate temperature compensation signal；
The DSP (2) is used to receive the square-wave signal and processes temperature signal unit (3) of flow signal processing unit (1) generation
The temperature compensation signal of generation, and the preliminary of detected fluid flow is calculated using the amount of cycles of square-wave signal in the unit time
Data are modified in conjunction with preliminary data of the temperature compensation signal to detected fluid flow, final to generate detected fluid flow
Precise information；
The CAN bus communication unit (4) is used to the detected fluid flow precise information that DSP (2) generate being sent to special purpose vehicle
Communication system.
2. a kind of compensation flow-measuring method of high precision temp frequency according to claim 1, which is characterized in that the flow
Signal processing unit (1) includes turbine, spiral case, air deflector, No.1 amplifying circuit and comparison circuit；
The inner wall of the spiral case is equipped with magnetoelectric induction coil；
The turbine is arranged inside spiral case,
After detected fluid passes through air deflector, impulse turbine makes the magnetoelectric induction coil of turbine circumgyration incision spiral case inner wall, magnetoelectricity sense
The variation of wire loop magnetic resistance generating period is answered, so that magnetoelectric induction coil flux amount changes, generation and detected fluid
The directly proportional pulse signal of uninterrupted, the pulse signal, using comparison circuit, produce after the amplification of No.1 amplifying circuit
Raw square-wave signal.
3. a kind of compensation flow-measuring method of high precision temp frequency according to claim 2, which is characterized in that the temperature
Signal processing unit (3) includes platinum resistance temperature probe and No. two amplifying circuits；
The opening of the platinum resistance temperature probe through air deflector, is placed in detected fluid；
The electric signal input end of No. two amplifying circuits is connected with the electrical signal that platinum resistance temperature is popped one's head in, No. two amplifications
The output end of circuit is the temperature compensation signal output end of processes temperature signal unit (3).
4. a kind of compensation flow-measuring method of high precision temp frequency according to claim 3, which is characterized in that the DSP
(2) the reversed Schmidt trigger of setting in；
The square-wave signal that the reversed Schmidt trigger is used to generate flow signal processing unit (1) rectifies.
5. a kind of compensation flow-measuring method of high precision temp frequency according to claim 1,2,3 or 4, which is characterized in that
The intelligent turbine flow transducer of the DSP further includes power converting circuit (5)；
The power converting circuit (5) is for being respectively flow signal processing unit (1), DSP (2) and processes temperature signal unit
(3) it powers.
6. a kind of compensation flow-measuring method of high precision temp frequency according to claim 1, which is characterized in that flow signal
Processing unit (1) carries out traffic frequency acquisition to detected fluid flow signal using " middle boundary's frequency " algorithm.
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