CN105784037B - All-digital waveform synthesis Coriolis flowmeter opens the device and method for the signal that shakes - Google Patents
All-digital waveform synthesis Coriolis flowmeter opens the device and method for the signal that shakes Download PDFInfo
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- CN105784037B CN105784037B CN201610289827.8A CN201610289827A CN105784037B CN 105784037 B CN105784037 B CN 105784037B CN 201610289827 A CN201610289827 A CN 201610289827A CN 105784037 B CN105784037 B CN 105784037B
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- mdac
- dds
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- microcontroller
- shakes
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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
- G01F1/8409—Coriolis or gyroscopic mass flowmeters constructional details
- G01F1/8422—Coriolis or gyroscopic mass flowmeters constructional details exciters
Abstract
The present invention relates to the device and methods that a kind of all-digital waveform synthesis Coriolis flowmeter opens the signal that shakes, which includes microcontroller, Direct Digital Frequency Synthesizers DDS, multiplying digital-to-analog converter MDAC, audio-frequency power amplifier；The device is after the power is turned on, DDS is controlled by microcontroller, constantly synthesis output 1Hz square-wave signals, control word is written to MDAC in microcontroller simultaneously, make to carry out amplitude modulation amplification according to control word size by the square-wave signal of MDAC, then through work(to fix multiple amplification so that the final amplitude of square-wave signal is adjusted to 9Vpp, the signal inlet flow buret, to realize that quickly opening for flowtube is shaken.
Description
Technical field
The present invention is directed the drive system of coriolis mass flowmeters, devise a kind of based on Harmonic Decomposition
Vibrating device and method are opened in the total word drives of 1Hz.
Background technology
Coriolis mass flowmeters (hereinafter referred Coriolis flowmeter) are using a kind of straight made of Coriolis principle
Formula mass flowmeter is connect, is one of Developing flowmeter the most rapid, Coriolis flowmeter can not only measure various routines
Liquid, while the measurement for the unconventional fluid such as can also apply to slurries, liquid gas and compressed natural gas, are widely used in oil
The industries such as chemical industry, food pharmaceutical.
Coriolis flowmeter mainly (is also known as by flowtube (also known as vibrating tube), sensor, signal processing system and drive system
Excitation system) composition.Wherein, the quality of drive system performance directly affects the overall measurement accuracy of flowmeter.Traditional drive
Dynamic circuit is made of analog circuit, is opened the process of shaking and is driven by noise, is existed and is started that the time is longer, opens the problems such as shaking poor robustness,
Simultaneously because the gain that noise provides is limited, when the amplitude of flowtube and frequency change, just it is unable to control flowtube and reaches
Stable vibration；Exist simultaneously the problems such as circuit structure is complicated, component is easy to aging, higher to environmental requirement, digital drive scheme
It is research hotspot in recent years.Many companies and R&D institution are directed to the drive system of Coriolis flowmeter, successfully have developed
Based on the digital driving method of direct digital synthesis technique (Direct Digital Frequency Synthesis, DDS), take
Obtained good performance and precision.Chinese patent discloses the initialization in a kind of Coriolis mass flowmeter for drive control and calculates
(R.L. horses Shanxi Nice, coriolis flowmeter are used for the initialization algorithm of drive control, Chinese patent, application number to method：
01806546.5, the applying date：2001.3.12), this kind of method is first to apply 1V, the step letter of duration 10ms to flowtube
Number, by the sensor feedback amplitude in flowtube whether enough to determine whether need increase step signal action time and
Amplitude size then increases the action time of step to 20ms such as the non-starting of oscillation of flowtube, and amplitude increases to 2V, such cycle criterion,
Requirement of shaking is opened until meeting.This method advantage is in the prior information for not needing flowtube intrinsic frequency, but its accumulated time mistake
It is few, it needs additionally to increase amplitude and open shaking；It is alternately sharp that a kind of positive and negative step of Coriolis mass flowmeter is also disclosed in Chinese patent
Excited method of slight and system (the positive and negative step alternative excitation vibration-starting method of Xu Ke armies Coriolis mass flowmeter and system, Chinese patent,
Application number：200910144210.7 the applying date：2009.7.23), the thinking of this kind of method is in the suitable position of vibrating flow tube
It sets, with positive and negative step alternative excitation, then flowtube output will constantly be reinforced, and final realization flowtube, which opens, shakes.But this kind of method is set
Count it is extremely complex, control process it is cumbersome, due to influences such as industrial environment noises, the zero mentioned in method is difficult to look for,
Even if a stagnant annulus b is arranged to avoid the system malfunction of grass in zero crossings, but the value of b is needed according to reality again
Noise size is set, and this method needs to determine the priori noise information at scene in advance in different operative scenarios, not
It can adaptive environment well.In fact, flowtube itself is equivalent to a narrow band filter, have extraordinary frequency-selecting special
Property, frequency opening near flowtube intrinsic frequency shake signal all can opening to shake and apply positive feedback effect to flowtube, therefore not
The signal of same frequency opens the time of shaking, opens effect of shaking and have a major impact for flowtube.The present invention is in theory analysis and largely
On experiment basis, it is proposed that the digital signal driving method of the 1Hz based on Harmonic Decomposition, and design and realize according to this method
A set of digital drive opens vibrating device.
Invention content
Technical problems to be solved
It shakes in order to avoid the shortcomings of the prior art, the present invention proposes that a kind of all-digital waveform synthesis Coriolis flowmeter opens
The device of signal.
Technical solution
A kind of all-digital waveform synthesis Coriolis flowmeter opens the device for the signal that shakes, it is characterised in that including microcontroller, directly
Connect digital frequency synthesizer DDS, multiplying digital-to-analog converter MDAC and audio-frequency power amplifier；Two data of microcontroller export
Pin connect respectively with the input pin of DDS and MDAC realize Waveform composition and amplitude modulation control function, the output pin of DDS with
The input pin of MDAC connects, and the output pin of MDAC and the input pin of audio-frequency power amplifier connect, Audio power amplifier
Device output opens the signal that shakes to Coriolis flowmeter.
A method of opening the signal that shakes using the device synthesis Coriolis flowmeter, it is characterised in that steps are as follows：
Step 1：After system electrification, microcontroller removes all interruptions and interrupt identification, what definition was connect with DDS, MDAC
Pin, and configuring DDS makes it be operated under square wave output services state；MDAC outputs are removed, configuration MDAC comes from microcontroller
Control command data be locked shift register in clock falling edge；
Step 2：Microcontroller makes DDS constantly send out 1Hz square-wave signals to DDS write frequency control words；
Step 3：Amplitude control words are written to MDAC in microcontroller, make MDAC to the 1Hz square-wave signals from DDS by amplitude
The corresponding ratio of control word is adjusted；
Step 4：After power amplifier is amplified the MDAC signals exported, export 9-10Vpp opens the signal that shakes.
Advantageous effect
A kind of all-digital waveform synthesis Coriolis flowmeter proposed by the present invention opens the device for the signal that shakes, the device and method gram
It has taken to simulate to open to shake and has opened the limitation for the signal that shakes with other numbers, had the advantages that：
1, single unit system and control method are simple, compared to other complicated hardware circuits and control method, can greatly reduce
Complexity is controlled, while this opens vibrating device and has also been multiplexed subsequent control flowtube stable vibration device, need not increase additional
Hardware spending, it is only necessary to increase software control part and can open and shake；
2, the method shaken is opened mainly by noise compared to analog drive system, hence it is evident that vibration velocity degree is opened in promotion, opens the effect stability that shakes
Reliably.The signal that shakes is opened compared to other numbers, can not only greatly reduce algorithm complexity and rate-determining steps, while opening vibration velocity degree
It is unaffected.Show originally to open by actual experiment shake signal method can be for the flowtube of intrinsic frequency higher (203Hz)
It opens and shakes in 3.0s, flowtube can be made to open in 4.0s for intrinsic frequency (91Hz) lower flowtube and shaken；
3, open that the signal that shakes is versatile, for intrinsic frequency 40-400Hz flowtube, all with this kind of device and method
It can be achieved quickly to open and shake, show that this kind of method opens the time of shaking and be no more than 6.2s by actual tests；
4, robustness is good, is shaken substantially not by influence of noises such as ambient noises, it can be achieved that quickly opening.
Description of the drawings
Fig. 1 is the hardware annexation of the present invention
Fig. 2 is the work step of the present invention
Specific implementation mode
In conjunction with embodiment, attached drawing, the invention will be further described：
To propose a kind of 1Hz based on Harmonic Decomposition digital for the digital drive system of Coriolis flowmeter by the present invention
Waveform composition Coriolis flowmeter opens the signal method that shakes, and has devised and embodied a set of digital driving device according to this method.
The device includes：Microcontroller, Direct Digital Frequency Synthesizers (hereinafter referred to as DDS), multiplying digital-to-analog converter are (hereinafter referred to as
MDAC), audio-frequency power amplifier (hereinafter referred to as power amplifier).The hardware annexation of the device is as shown in Figure 1.The number of microcontroller
It is connect with the input pin of DDS and MDAC according to output pin, the output pin of DDS and the input pin of MDAC connect, MDAC's
The input of output pin and power amplifier connects, and the output pin of power amplifier is the output end of the present apparatus.
After the power is turned on, DDS is controlled the device by microcontroller, constantly synthesis output 1Hz square-wave signals, while microcontroller to
Control word is written in MDAC, makes to carry out amplitude modulation amplification according to control word size by the square-wave signal of MDAC, then through work(with fixed times
Number amplification so that the final amplitude of square-wave signal is adjusted to 9Vpp, the signal inlet flow buret, to realize quickly opening for flowtube
It shakes.It is used here as the reason of MDAC amplitude modulation and power amplifier amplification, on the one hand, the present invention pertains only to open the process of shaking, and is not related to follow-up
Controlling of amplitude process, during controlling of amplitude, relying solely on the own amplification factor of MDAC can not meet the requirements, therefore
It needs to be amplified with power amplifier again, MDAC mainly realizes that amplification factor is adjusted by program according to the feedback signal of flowtube, work(
It puts and mainly realizes that signal can open the energy requirement that shakes according to flowtube and be amplified.At the same time, it is desirable to which the device can be multiplexed in flowtube
Under Qi Zhen and flowtube fixed ampllitude working condition, to reduce additional hardware spending.
For this starting of oscillation signal propose open vibrating device hardware annexation as shown in Figure 1, microcontroller respectively with DDS,
The control function of Waveform composition and amplitude modulation is realized in MDAC connections；The output end of DDS is connected with the analog input end of MDAC, power amplifier
Input be connected with the output end of MDAC, the output end of power amplifier is the output end of drive system.
What this method was taken is the 1Hz signal driving methods based on Harmonic Decomposition, is described below and is successfully driven with 1Hz signals
The reason of.
Vibrating flow tube system itself is equivalent to a narrow band filter, has extraordinary selecting frequency characteristic, when driving is believed
Number frequency it is equal or close with flowtube intrinsic frequency when, it is minimum that flowtube opens the required energy of shaking, and can open rapidly shake at this time, and
Decay the amplitudes of other frequency signals, to reach resonant condition.According to harmonic analysis method, any period letter about the time
Number can be launched into fourier series, i.e., unlimited number of containing fundamental frequency and a series of sine of harmonic waves for fundamental wave integral multiple
The weighted sum of wave component and cosine component then has if f (t) is periodic function
Wherein,It is fundamental wave angular frequency, T is period, an、bnIt is the coefficient of Fourier space, multinomial first itemDC component is represented, n representatives are n order harmonics.
Using f in the design0The square wave of=1Hz, then fundamental wave angular frequency is ω0=2 π f0, Harmonic Decomposition can indicate
For：
Since its fundamental frequency is 1Hz, higher hamonic wave is the odd number frequency multiplication of fundamental frequency, harmonic components have 1Hz, 3Hz,
5Hz ... ... is incremented by with odd-multiple successively, and 2Hz is only differed between the harmonic frequency of signal, i.e., if with DDS synthetic waveforms,
In using 1Hz square waves as starting of oscillation signal, harmonics frequency component is most.At flowtube starting of oscillation initial stage, due to not detecting
When outflow pipe intrinsic frequency, the abundant square wave of harmonic component is easier to make flowtube starting of oscillation, therefore the side 1Hz compared with other waveforms
Wave opens the signal that shakes and must have higher hamonic wave near flowtube intrinsic frequency；It is put by power amplifier additionally, due to the square wave of 1Hz
It keeps the time of the amplitude that can be up to 1 second in higher amplitude after big, can also meet flowtube and open wanting for the required energy that shakes
It asks.The present apparatus and method are based on above 2 reasons, can finally realize that quickly opening for flowtube is shaken.
The work step of this method is：
1, it initializes.Upon power-up of the system, microcontroller is by all interruptions of program reset and interrupt identification, definition with
The pin of DDS, MDAC connection, and configuring DDS makes it be operated under square wave output services state；Initialize MDAC functions, micro-control
Device processed removes MDAC outputs, and configures the control command data from microcontroller and be locked shift LD in clock falling edge
Device；
2, DDS is enabled.Microcontroller makes DDS constantly export 1Hz square-wave signals to DDS write frequencies, which uses
DDS gives tacit consent to amplitude, is set as V1；
3, MDAC is enabled.Amplitude control words are written to MDAC in microcontroller, make MDAC to the signal from DDS by control word
Corresponding ratio is adjusted, and the coefficient of adjustment here is E1；Output TTL voltage magnitude 3.3Vpp are given tacit consent to for DDS, here
Amplification factor be (1800/4096)；
4, power amplifier is enabled.Power amplifier exports the signal from MDAC with 6-7 times (amplification factor E2) amplification, makes most
The amplitude (i.e. V1E1E2) of whole output signal is between 9-10Vpp.
Claims (1)
1. a kind of method that fully synthetic Coriolis flowmeter opens the signal that shakes opens the signal that shakes using all-digital waveform synthesis Coriolis flowmeter
Device, to open the device for the signal that shakes include microcontroller, Direct Digital frequency to all-digital waveform synthesis Coriolis flowmeter
Synthesizer DDS, multiplying digital-to-analog converter MDAC and audio-frequency power amplifier；Two data output pins of microcontroller respectively with
DDS connects the control function for realizing Waveform composition and amplitude modulation, the input of the output pin and MDAC of DDS with the input pin of MDAC
Pin connects, and the output pin of MDAC and the input pin of audio-frequency power amplifier connect, and audio-frequency power amplifier output, which is opened, shakes
Signal is to Coriolis flowmeter；It is characterized in that steps are as follows：
Step 1：After system electrification, microcontroller removes all interruptions and interrupt identification, defines the pin being connect with DDS, MDAC,
And configuring DDS makes it be operated under square wave output services state；MDAC outputs are removed, controls of the MDAC from microcontroller is configured
Order data is locked shift register in clock falling edge；
Step 2：Microcontroller makes DDS constantly send out 1Hz square-wave signals to DDS write frequency control words；
Step 3：Amplitude control words are written to MDAC in microcontroller, and MDAC is made to control the 1Hz square-wave signals from DDS by amplitude
The corresponding ratio of word is adjusted；
Step 4：After power amplifier is amplified the MDAC signals exported, export 9-10Vpp opens the signal that shakes.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610289827.8A CN105784037B (en) | 2016-05-04 | 2016-05-04 | All-digital waveform synthesis Coriolis flowmeter opens the device and method for the signal that shakes |
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| CN201610289827.8A CN105784037B (en) | 2016-05-04 | 2016-05-04 | All-digital waveform synthesis Coriolis flowmeter opens the device and method for the signal that shakes |
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| CN107167195B (en) * | 2017-05-24 | 2019-04-19 | 西北工业大学 | A kind of Coriolis mass flowmeter vibration-starting method based on digital driving method |
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| CN1837758A (en) * | 2006-03-02 | 2006-09-27 | 西安东风机电有限公司 | Digital signal resolving device and method for Coriolis mass flowmeter based on harmonious decomposition |
| CN101608940A (en) * | 2009-07-23 | 2009-12-23 | 合肥工业大学 | Positive and negative step alternative excitation vibration-starting method of Coriolis mass flowmeter and system |
| CN103528634A (en) * | 2013-10-23 | 2014-01-22 | 山东大学 | Coriolis mass flow meter cloud transmission digital signal processing device and method |
| CN103900653A (en) * | 2012-12-31 | 2014-07-02 | 上海一诺仪表有限公司 | Method for calculating phase difference in Coriolis mass flow meter |
| CN103984228A (en) * | 2014-05-31 | 2014-08-13 | 福州大学 | Method for designing Coriolis mass flow meter digital drive system |
| CN104501890A (en) * | 2015-01-16 | 2015-04-08 | 合肥工业大学 | Control method for coriolis mass flow tube of variable sensor signal setting value |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7490521B2 (en) * | 2005-11-15 | 2009-02-17 | Endress + Hauser Flowtec Ag | Measurement transducer of vibration type |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1837758A (en) * | 2006-03-02 | 2006-09-27 | 西安东风机电有限公司 | Digital signal resolving device and method for Coriolis mass flowmeter based on harmonious decomposition |
| CN101608940A (en) * | 2009-07-23 | 2009-12-23 | 合肥工业大学 | Positive and negative step alternative excitation vibration-starting method of Coriolis mass flowmeter and system |
| CN103900653A (en) * | 2012-12-31 | 2014-07-02 | 上海一诺仪表有限公司 | Method for calculating phase difference in Coriolis mass flow meter |
| CN103528634A (en) * | 2013-10-23 | 2014-01-22 | 山东大学 | Coriolis mass flow meter cloud transmission digital signal processing device and method |
| CN103984228A (en) * | 2014-05-31 | 2014-08-13 | 福州大学 | Method for designing Coriolis mass flow meter digital drive system |
| CN104501890A (en) * | 2015-01-16 | 2015-04-08 | 合肥工业大学 | Control method for coriolis mass flow tube of variable sensor signal setting value |
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