CN103148897A - Digital intelligent vortex shedding flowmeter based on DSP and metering method of same - Google Patents

Abstract

The invention discloses a DSP-based digital intelligent vortex flowmeter and its measurement method, including a signal detection module, a spectrum analysis module, a signal output module, a man-machine interface module, a parameter storage module, a monitoring module and a power supply module, wherein the signal The detection module includes a vortex signal detection circuit and an interference detection circuit. The spectrum analysis module is completed by a digital signal processing chip, including an analog-to-digital conversion unit, a digital band-pass filter unit, an interpolation FFT calculation unit, and an intelligent algorithm rule unit. On the basis of two-way signal detection and spectrum analysis, the metering method of the present invention can effectively extract the vortex signal frequency under the condition that the vortex signal intensity is less than the on-site vibration interference intensity through intelligent algorithm rules, and has the advantages of anti-interference, reliability and stability. Sexuality and other aspects have a good performance.

Description

A DSP-based digital intelligent vortex flowmeter and its measurement method

technical field

The invention belongs to the field of flow detection, and in particular relates to a digital intelligent vortex flowmeter based on a digital signal processor DSP and a measurement method.

Background technique

The vortex flowmeter develops rapidly and its application range is more and more extensive. Vortex sensor and vortex signal frequency extraction technology are two key technologies in the design process of vortex flowmeter. The vortex sensor involves the knowledge of fluid mechanics, and we pay more attention to the related research of the secondary instrument based on the frequency extraction technology of the vortex signal.

The traditional vortex signal extraction method is mainly realized through four steps of amplification, filtering, shaping, and counting. The first three main tasks are completed by analog hardware circuits, and the counting is realized by MCU. The system designed by this vortex signal extraction method has a low range and is susceptible to electromagnetic and field interference. From the traditional method, it can be concluded that there are two technical points of vortex signal extraction, which are signal filtering and acquisition of vortex signal spectrum information. Since the research on signal spectrum analysis methods is relatively mature, scholars have studied signal analysis methods such as wavelet transform, modern spectrum analysis, notch filter, and FFT in vortex street signal extraction. Compared with traditional methods, the frequency resolution of these spectrum analysis methods implemented by software algorithms is higher than traditional methods, but considering the real-time nature of offline work of secondary instruments, these methods are relatively rare in practical applications. FFT can meet the real-time requirements, but it often causes spectrum leakage due to the existence of "fence effect".

The vortex street signal has the characteristics of easy noise interference in the low frequency band and obvious characteristics in the high frequency band, and it is easy to be interfered by on-site noise in the low frequency band. The current research on vortex signal extraction is often based on single-channel signals. The result is that when the interference signal is stronger than the vortex signal, the former will cover the latter, and the final vortex signal is actually an interference signal.

Contents of the invention

Aiming at technical problems such as the hardware signal processing circuit is susceptible to external interference, the real-time and accuracy requirements of the instrument offline work, and the defects of single-channel sensing signal acquisition, the present invention provides a digital intelligent vortex flowmeter based on DSP and its measurement method.

A digital intelligent vortex flowmeter based on DSP, including a signal detection module, a signal output module, a man-machine interface module and a power module, the signal detection module includes a vortex signal detection circuit and an interference detection circuit; the intelligent vortex The flow meter also includes a spectrum analysis module, which includes:

An analog-to-digital conversion unit, configured to convert the two detection signals output by the signal detection module into digital signals;

A digital band-pass filter unit, configured to band-pass filter the digital signal output by the analog-to-digital conversion unit;

An interpolation FFT calculation unit, configured to perform spectrum analysis on the filtered digital signal output by the digital bandpass filter unit, to obtain the spectrum information of the harmonics of the two detection signals of the signal detection module;

The intelligent algorithm rule unit is used to compare the spectrum information of the harmonics of the two detection signals, and extract the frequency of the vortex signal.

Further, the intelligent vortex flowmeter also includes a monitoring module connected to the spectrum analysis module, and the monitoring module is a watchdog circuit. The watchdog circuit sets a certain duty cycle as the time period for feeding the dog. If the smart vortex flowmeter of the present invention breaks down in work, it cannot feed the dog in time, and the watchdog circuit will reset the DSP chip. The terminal sends a system reset signal.

Further, the intelligent vortex flowmeter also includes a parameter storage module connected to the spectrum analysis module, which is used to store important parameters such as accumulated flow, so as to prevent parameters from being lost when the flowmeter is powered off.

Further, the hardware circuits of the vortex signal detection circuit and the interference detection circuit both include a sensor, a charge amplifier and a pre-filter circuit, and the sensor is a piezoelectric sensor. It is used to collect vortex street signals and on-site vibration interference in two channels, amplify them, and then output them to the spectrum analysis module after low-pass filtering and buffer isolation.

Further, the spectrum analysis module is a digital signal processor DSP (Digital Signal Processing, DSP for short). The main work of the vortex flowmeter, including filtering, signal spectrum analysis, and intelligent algorithm rules for eliminating main interference on site, are all implemented in DSP through software.

Further, the digital intelligent vortex flowmeter also includes a voltage stabilizing circuit, and the voltage stabilizing circuit includes a voltage stabilizer for converting the reference voltage output by the power supply module into the input of the analog-to-digital conversion module Voltage, the special voltage stabilization circuit is better than the internal reference voltage in terms of stability.

The present invention also proposes a measurement method based on the above-mentioned digital intelligent vortex flowmeter, comprising steps:

(1) Detect the vortex signal and the interference signal respectively to obtain two detection signals;

(2) Sampling the detected two detection signals and converting them into digital signals;

(3) Filter the digital signal and perform amplitude-based interpolation FFT to obtain the spectrum information of the harmonics of the two detection signals;

(4) Compare the spectrum information of the harmonics of the two detection signals, and extract the frequency of the vortex signal through intelligent algorithm rules;

(5) Output flow metering information after conversion.

Wherein, the spectrum information of the harmonic includes the average value of the harmonic amplitude, the amplitude of the harmonic, and the frequency index value of the harmonic.

Further, the step (3) includes the steps of:

(3.1), filter the digital signal, perform FFT on the filtered digital signal, store the spectrum information of the corresponding harmonic, and the first one of the storage array is the average value of the harmonic amplitude;

(3.2) Determine the main lobe through the spectrum, find the maximum amplitude spectral line in the main lobe, and record its amplitude information X1 and frequency index value K1;

(3.3) Find the spectral lines corresponding to the frequency index values (K1-1) and (K1+1), and the spectral line with the larger amplitude among the two spectral lines is recorded as the second largest value spectral line, and its amplitude is X2, and the frequency index value is K2;

(3.4), calculate the frequency index value correction parameter δ through X1 and X2, the specific calculation is as follows

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ;</span>$

(3.5). Finally, the frequency index K of the main frequency signal can be obtained from the correction parameters δ and K1. The specific calculation is as follows:

K=K1±δ.

Further, assume that A1 is the maximum harmonic amplitude of the vortex signal branch, A2 is the maximum harmonic amplitude of the interference signal branch, and F1 is the frequency index of the spectral line corresponding to the maximum harmonic amplitude of the vortex signal branch F2 is the frequency index value of the spectral line corresponding to the maximum harmonic amplitude of the interference signal branch, Aa1 is the average amplitude of the vortex signal branch, Aa2 is the average amplitude of the interference signal branch, and F is the final vortex street signal main frequency frequency index value, then the step (4) includes the steps of:

(4.1) Compare the maximum value of the harmonic amplitude of the two detection signals. If A1<A2, it means that the measurement is abnormal and is illegal data. The vortex flowmeter will give an abnormal warning and give up the measurement result this time; if A1≧A2 , then go to the next step;

(4.2) Determine whether the maximum harmonic amplitude values A1 and A2 of the two detection signals are equal. If they are equal, continue to compare the average amplitude values of the two harmonics. If Aa1=Aa2, it can be judged that the vortex street signal branch is Empty tube, end; if Aa1≠Aa2, reset the amplitudes of the spectral lines corresponding to F1 and F2 to zero, and return to step (4.1); if A1>A2, proceed to the next step;

(4.3) Compare F1 and F2, if F1≧F2, then judge the frequency index value of the vortex signal to be F1; otherwise, it means that the measurement is abnormal, which is illegal data, and the vortex flowmeter will issue an abnormal warning and give up the measurement result this time .

Compared with the traditional method, the DSP-based digital intelligent vortex flowmeter and its measurement method proposed by the present invention only use one DSP, reduce the number of devices, reduce the cost, enhance the anti-interference and reliability, and use digital Chebyshev band-pass filter The implementation of software algorithm improves the flexibility of the system for filtering; the use of amplitude-based interpolation FFT meets the real-time requirements of the system's offline work, and at the same time improves the lack of spectrum leakage caused by FFT due to the "fence effect", improving The accuracy of spectrum analysis is improved; at the same time, the intelligent algorithm rules widen the low-frequency range, which can effectively extract the vortex signal frequency when the vortex signal intensity is lower than the on-site vibration interference intensity; based on two-way signal detection and two-way signal spectrum analysis, Therefore, the measurement range of the low frequency band can be expanded, and the main frequency signal detection when the interference intensity is greater than the vortex street signal intensity can be completed.

Description of drawings

Fig. 1 is a schematic structural view of a digital intelligent vortex flowmeter of the present invention;

Fig. 2 is the circuit diagram of charge amplifier in the detection circuit of the present invention;

Fig. 3 is a pre-filter circuit diagram in the detection circuit of the present invention;

Fig. 4 is the circuit diagram of the voltage-stabilizing generating circuit of the analog-to-digital conversion unit of the present invention;

Fig. 5 is the watchdog circuit diagram of monitoring module of the present invention;

Fig. 6 is a flow chart of the digital intelligent vortex flow metering method of the present invention;

Fig. 7 is the flow chart of the interpolation FFT algorithm based on amplitude in the present invention;

Fig. 8 is a flowchart of intelligent algorithm rules of the present invention.

Detailed ways

The technical solution of the present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments, and the following embodiments do not constitute a limitation of the present invention.

The present invention provides a digital intelligent vortex flowmeter based on DSP, the hardware structure of which is shown in Figure 1, including a signal detection module, a spectrum analysis module, a signal output module, a man-machine interface module, a parameter storage module, a monitoring module and power module. The signal detection module includes two signal detection circuits, namely the vortex signal detection circuit and the interference detection circuit, one for collecting the vortex signal, including the vortex signal and field vibration interference, and the other for collecting field vibration interference. The hardware processing circuits of the two detection circuits are the same, including sensors, charge amplifiers, and pre-filtering.

As shown in Figure 2, the charge amplifier unit is mainly used to amplify the charge of the piezoelectric sensor signal, which includes an operational amplifier U2, three resistors R3, R4, R5, four capacitors C3, C4, C5, C6, and an operational amplifier The OP07 of TI Company is used; the connection relationship is: one end of C3, R4, and C5 is connected to port 3 of U2, one end of C4, R5, and C6 is connected to port 2 of U2, and ports 7 and 4 of U2 are respectively connected to Positive and negative 12V DC, the No. 6 port of U2 outputs the amplified analog signal and is connected to the other end of R5 and C6, the other end of R4 and C5 is connected to the ground, the other end of C3 and one end of R3 are connected to the sensor signal input end, The other end of C4 and the other end of R3 are connected to the other input end of the sensor signal.

As shown in Figure 3, it is the circuit diagram of pre-filtering, which performs simple low-pass filtering on the signal, and plays the role of buffering and isolation. It includes an operational amplifier U1B, 2 resistors R12, R23, 1 capacitor C27, and a regulator Tube D2 and the voltage regulator tube play a role in limiting the maximum voltage value. The operational amplifier uses TI's LM324N; the connection relationship is: one end of R12, R23, and C27 is connected to the No. 5 port of U1B, and the other end of R12 is connected to the charge amplifier unit The output terminals of R23 and C27 are connected to the ground, the ports 6 and 7 of U1B are connected to the inverting terminal of the voltage regulator tube D2, the positive terminal of D2 is grounded, and the output port of U1B, which is port 7, is connected to the spectrum The input terminals of the analog-to-digital conversion unit (A/D) in the analysis module are connected.

The frequency spectrum analysis module of the present invention is realized by a digital signal processor DSP, including a 10-bit analog-to-digital conversion unit (A/D), a digital band-pass filter unit, an interpolation FFT calculation unit and an intelligent algorithm rule unit. The main work of the vortex flowmeter, including filtering, signal spectrum analysis, and intelligent algorithm rules for eliminating main interference on site, are all implemented in DSP through software. The DSP main control chip adopted in this embodiment is TMS32LF2407A of TI Company.

The two-way detection signals output by the signal detection module are converted into digital signals through the analog-to-digital conversion unit in the DSP, and input to the digital band-pass filter unit, and then calculated by the interpolation FFT calculation unit, and the spectrum information of the calculated two-way signals On the basis of , the frequency of the vortex signal is extracted through the intelligent algorithm rule unit. Among them, the digital band-pass filter unit adopts a digital Chebyshev band-pass filter, which avoids the analog interference brought by hardware filtering. The digital Chebyshev band-pass filter is a commonly used filtering technology. The width of the pipe is based on the diameter of the pipe and the medium type of the fluid in the pipe; followed by the selection of three parameters such as cut-off frequency, passband attenuation ripple ratio, and stopband attenuation ratio, which are determined according to engineering requirements. The specific digital filter design is divided into four steps, as follows:

(1) Analog low-pass filter design;

(2) Analog frequency band conversion - low-pass variable band-pass;

(3) Filter transformation—analog to digital, using two-line transformation;

(4) Calculate the filter parameters and analyze whether the parameters meet the design requirements.

The designed digital Chebyshev band-pass filter is used to perform digital band-pass filtering on the sampled data. This function mainly realizes the function of analog hardware filtering in the traditional method.

It should be noted that the analog-to-digital conversion unit in the DSP samples the two detection signals, the sampling frequency is set according to the industrial application background, and the number of sampling points N is an integer power of 2. For example, the number of sampling points in this embodiment is 128, which is 2 to the 7th power. The digital band-pass filter unit performs digital filtering on the sampled data, using a Chebyshev band-pass filter, whose bandwidth frequency is set according to the specific industrial application background, and the bandwidth of the vortex signal corresponding to different calibers and fluid media is different , which will not be repeated here.

The A/D in the DSP chip can provide a reference voltage through the internal circuit, but the special voltage stabilization generating circuit is better than the internal reference voltage in stability. In this embodiment, the 2.5V voltage generated by the external voltage stabilization generating circuit is used as the A/D voltage. The reference source of D, as shown in Figure 4, the generating circuit includes a resistor R9, a capacitor CL, and a voltage regulator U5. In this embodiment, TI’s TL431 is sampled; the connection relationship is: R9, CL One end of R9, the reference output end of U5 is connected to the A/D reference source input end, the other end of R9, the anode end of U5 is connected to VCC, the other end of CL, the cathode port of U5 is grounded.

The sampled data filtered by the digital band-pass filter unit is input to the interpolation FFT calculation unit for spectrum calculation, and the harmonic spectrum information of the two detection signals of the vortex signal channel and the interference signal channel are respectively obtained. The harmonic spectrum information includes The average value of the harmonic amplitude, the harmonic amplitude value, and the harmonic frequency index value corresponding to the harmonic amplitude value. The algorithm used is the magnitude-based interpolated FFT.

The frequency spectrum information output by the interpolation FFT calculation unit is input to the intelligent algorithm rule unit for comparison, and the frequency of the vortex signal is extracted. On the basis of the three parameter estimates of the two-way signal amplitude, frequency index, and amplitude average value, the current vibration interference is eliminated according to the rules of the intelligent algorithm, and the frequency of the vortex street signal is obtained.

The signal output module includes RS485 communication channel, 4~20mA current output channel and pulse output channel. RS485 communication is mainly used for the communication between the flowmeter and the upper computer, the current output channel is used for the industrial application control of the current transmitter, and the pulse output channel is used for the cumulative flow quantitative output. In order to prevent external circuits from affecting the main control chip, hardware circuits such as RS485 communication, pulse output, and 4~20mA current output are connected to the I/O of the DSP control chip through photocoupler devices.

The man-machine interface mainly includes liquid crystal display and keys, the liquid crystal display is used to display the flow rate and cumulative flow, and the keys are used for parameter setting. The parameter storage module adopts the electrically erasable programmable read-only memory EEPROM, which is used to store important parameters such as accumulated flow and prevent the parameters from being lost when the flowmeter is powered off.

In order to monitor the work of the system correctly, the present invention provides an off-chip monitoring module. The present embodiment adopts a watchdog circuit. In this embodiment, 140 ms is used as a cycle to feed the watchdog. Feed the dog in time, then the watchdog circuit will send a system reset signal to the reset terminal of the DSP chip. In this embodiment, the watchdog circuit unit is as shown in Figure 5, including a watchdog integrated chip U4, 1 resistor R7, and the watchdog integrated chip adopts the CAT823 of ON Semiconductor; its connection relationship is: one end of R7, 1 of U4 The other end of R7 is connected to the No. 2 port of U4, the No. 3 port of U4 is connected to the other end of the button that is grounded, and the No. 4 port of U4 is connected to the dog feeding program output port of the DSP chip. The No. 5 port of U4 is connected to VCC, and VCC is a positive 3V DC voltage.

The present invention also proposes a measurement method of a digital intelligent vortex flowmeter based on DSP at the same time, as shown in Figure 6, including steps:

Step 61. Detecting the vortex signal and the interference signal respectively to obtain two detection signals;

Step 62, sampling the detected two detection signals and converting them into digital signals;

Step 63, filter the digital signal, perform amplitude-based interpolation FFT, and obtain the spectrum information of the harmonics of the two detection signals;

Step 64, comparing the spectrum information of the harmonics of the two detection signals, and extracting the frequency of the vortex signal through intelligent algorithm rules;

Step 65, output flow metering information after conversion. (How to convert frequency information into flow measurement information output?)

Through the above step 64, the amplitude and frequency index value information of the harmonic with the highest intensity in the vortex signal can be obtained. This harmonic is the main frequency vortex signal, and its frequency can be calculated by the following formula:

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; N</span>}}\mathrm{<span\; class="notranslate">\; K</span>}$

Where f is the frequency of the vortex signal, f _s is the A/D sampling frequency, N is the number of sampling points, and K is the above-mentioned frequency index value. The calculated vortex signal frequency is converted in the signal output module to output flow information.

The present invention collects the vortex street signal and the interference signal respectively in two ways, one is used to collect the vortex street signal, which includes the vortex street signal and the on-site vibration interference, and the other way collects the on-site vibration interference; the two-way detected signals are sampled, Convert it into a digital signal and perform digital band-pass filtering; perform interpolation FFT on the filtered signal to obtain the spectrum information of the harmonics of the two detection signals, and then propose vibration interference through intelligent algorithm rules to obtain the frequency of the vortex signal.

Specifically, the method of performing amplitude-based interpolation FFT to obtain the spectral information of the harmonics of the signal is shown in Figure 7, including steps:

Step 71: Filter the digital signal, perform FFT on the filtered digital signal, store the spectrum information of the corresponding harmonic, and the first element of the storage array is the average value of the harmonic amplitude.

For example, if the storage array is DATA[], then DATA[0] is the average value of the amplitude, DATA[i] is the amplitude of the i-th harmonic, and i is the frequency index value of the harmonic.

Step 72: Determine the main lobe through the frequency spectrum, find the maximum amplitude spectral line in the main lobe, and record its amplitude information X1 and frequency index value K1.

Step 73. Find the spectral lines corresponding to the frequency index values (K1-1) and (K1+1), and record the spectral line with the larger amplitude among the two spectral lines as the next largest value spectral line, and its amplitude is X2, the frequency index value is K2;

Step 74, calculate the frequency index value correction parameter δ from X1 and X2, the specific calculation is as follows

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}$

Step 75. Finally, the frequency index K of the main frequency signal can be obtained from the correction parameters δ and K1, and the specific calculation is as follows

K=K1±δ.

Compared with the FFT, this calculation method of the frequency spectrum modifies the frequency index on the basis of the FFT. The correction parameters are obtained from the amplitude information of the two spectral lines with the largest amplitudes in the main lobe of the FFT spectrum, and the frequency information of the main frequency signal can be obtained from the frequency index estimation of the spectral lines with the largest amplitudes in the main lobe and the correction parameters. It should be noted that when K1>K2, the frequency index of the main frequency signal is K=K1-δ, and when K1<K2, the frequency index of the main frequency signal is K=K1+δ. The main frequency signal here refers to the signal of the detected branch.

After obtaining the spectrum information of the two signals, the frequency of the vortex signal can be extracted through the intelligent algorithm rules. The process of implementing the intelligent algorithm rules is shown in Figure 8, including steps:

Step 81. Compare the maximum value of the harmonic amplitude of the two signals. If A1<A2, it means that the measurement is abnormal and the data is illegal. The vortex flowmeter gives an abnormal warning and discards the measurement result; otherwise, go to the next step.

Step 82. Determine whether the maximum values of the harmonic amplitudes of the two signals are equal. If they are equal, continue to compare the average values of the two harmonic amplitudes. If Aa1=Aa2, it can be judged that the vortex street signal branch is an empty pipe. End ; If Aa1≠Aa2, reset the amplitudes of the spectral lines corresponding to F1 and F2 to zero, and return to step (1); if A1>A2, proceed to the next step.

Step 83. Compare F1 and F2. If F1≧F2, judge that the frequency index value of the vortex signal is F1; otherwise, it means that the measurement is abnormal, which is illegal data. The vortex flowmeter issues an abnormal warning and discards the measurement result this time. .

In fact, when F1=F2, the frequency of the vortex signal is equal to the frequency of the interference signal, and the frequency index value is F1. If F1>F2, the frequency index value of the vortex signal is F1.

It should be noted that there are two prerequisites for the implementation of intelligent algorithm rules: one is the hardware prerequisite, that is, two-way signal detection; the other is the software prerequisite, that is, the interpolation FFT spectrum analysis. The intelligent algorithm rules realize that the vortex signal can still be extracted under the condition that the interference is stronger than the vortex signal strength. The most obvious feature of the vortex signal is that the low frequency band is susceptible to interference. Traditional methods to deal with low-frequency interference often take measures to reduce the low-frequency range. The intelligent algorithm rules in the present invention can effectively improve this deficiency. When the vortex frequency is greater than the interference frequency, the spectrum characteristics of the two signals are that the maximum value of the harmonic amplitude in the vortex signal branch is greater than the maximum harmonic amplitude in the interference signal branch, and the corresponding frequency index of the former is greater than that of the latter The corresponding frequency index; when the frequency of the vortex street is equal to the interference frequency, the spectral characteristics of the two signals are that the maximum value of the harmonic amplitude in the vortex signal branch is not equal to the maximum value of the harmonic amplitude in the interference signal branch, but The corresponding frequency indexes of the two are equal, and the average value of the amplitude of the vortex signal branch is greater than the average value of the amplitude of the interference signal branch; when the vortex frequency is smaller than the interference frequency, the spectral characteristics of the two signals are, The maximum value of the harmonic amplitude in the branch is equal to the maximum value of the harmonic amplitude in the branch of the interference signal. At this time, if the average values of the amplitudes of the two channels are equal, it can be known that the vortex street signal branch is an empty tube; when the vortex street frequency is lower than the interference frequency, the spectrum characteristics of the two signals are that the harmonic amplitude The maximum value is equal to the maximum value of the harmonic amplitude in the interference signal branch. If the average amplitude of the vortex signal branch is greater than the average amplitude of the interference signal branch, it can be known that the frequency of the interference signal covers the frequency of the vortex signal. . When the interference frequency covers the vortex signal frequency, in order to obtain the accurate vortex frequency, it is necessary to eliminate the spectrum information of the harmonic with the largest amplitude in the two channels, and then extract the vortex frequency again according to the algorithm rules from the remaining harmonics .

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and changes according to the present invention. deformation, but these corresponding changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. A digital intelligent vortex flowmeter based on DSP, comprising a signal detection module, a signal output module, a man-machine interface module and a power supply module, characterized in that the signal detection module comprises a vortex signal detection circuit and an interference detection circuit The intelligent vortex flowmeter also includes a spectrum analysis module, and the spectrum analysis module includes: An analog-to-digital conversion unit, configured to convert the two detection signals output by the signal detection module into digital signals; A digital band-pass filter unit, configured to band-pass filter the digital signal output by the analog-to-digital conversion unit; An interpolation FFT calculation unit, configured to perform spectrum analysis on the filtered digital signal output by the digital bandpass filter unit, to obtain the spectrum information of the harmonics of the two detection signals of the signal detection module; The intelligent algorithm rule unit is used to compare the spectrum information of the harmonics of the two detection signals, and extract the frequency of the vortex signal. 2. The digital intelligent vortex flowmeter based on DSP according to claim 1, characterized in that: the intelligent vortex flowmeter also includes a monitoring module connected to the spectrum analysis module, and the monitoring module is a watchdog circuit . 3. The digital intelligent vortex flowmeter based on DSP according to claim 1, characterized in that: the intelligent vortex flowmeter further comprises a parameter storage module connected with the spectrum analysis module. 4. According to claim 1, 2, the digital intelligent vortex flowmeter based on DSP according to any one of claims 3, it is characterized in that: the hardware circuits of the vortex signal detection circuit and the interference detection circuit all include sensors, charge An amplifier and a pre-filter circuit, the sensor is a piezoelectric sensor. 5. The digital intelligent vortex flowmeter based on DSP according to claim 1, characterized in that: the spectrum analysis module is a digital signal processor (DSP). 6. The digital intelligent vortex flowmeter based on DSP according to claim 1, characterized in that: the digital intelligent vortex flowmeter also includes a voltage stabilizing circuit, and the voltage stabilizing circuit includes a voltage regulator for for converting the reference voltage output by the power supply module into the input voltage of the analog-to-digital conversion module. 7. A DSP-based digital intelligent vortex flow metering method, characterized in that it comprises steps: (1) Detect the vortex signal and the interference signal respectively to obtain two detection signals; (2) Sampling the detected two detection signals and converting them into digital signals; (3) Filter the digital signal and perform amplitude-based interpolation FFT to obtain the spectrum information of the harmonics of the two detection signals; (4) Compare the spectrum information of the harmonics of the two detection signals, and extract the frequency of the vortex signal through intelligent algorithm rules; (5) Output flow metering information after conversion. 8. The digital intelligent vortex flow metering method based on DSP according to claim 7, characterized in that, the frequency spectrum information of the harmonics includes the amplitude mean value of the harmonics, the amplitude of the harmonics and the frequency of the harmonics index value. 9. The DSP-based digital intelligent vortex flow metering method according to claim 8, characterized in that the step (3) includes the steps of: (3.1), filter the digital signal, perform FFT on the filtered digital signal, store the spectrum information of the corresponding harmonic, and the first one of the storage array is the average value of the harmonic amplitude; (3.2) Determine the main lobe through the spectrum, find the maximum amplitude spectral line in the main lobe, and record its amplitude information X1 and frequency index value K1; (3.3) Find the spectral lines corresponding to the frequency index values (K1-1) and (K1+1), and the spectral line with the larger amplitude among the two spectral lines is recorded as the second largest value spectral line, and its amplitude is X2, and the frequency index value is K2; (3.4) Calculate the frequency index value correction parameter δ through X1 and X2, and the specific calculation is as follows: $\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ;</span>$ (3.5). Finally, the frequency index K of the main frequency signal can be obtained from the correction parameters δ and K1. The specific calculation is as follows K=K1±δ. 10. The DSP-based digital intelligent vortex flow metering method according to claim 9, wherein it is assumed that A1 is the maximum harmonic amplitude value of the vortex signal branch, and A2 is the maximum harmonic amplitude value of the interference signal branch F1 is the frequency index value of the spectral line corresponding to the maximum harmonic amplitude of the vortex street signal branch, F2 is the frequency index value of the maximum harmonic amplitude of the interference signal branch corresponding to the spectral line, Aa1 is the vortex street signal branch The average value of the amplitude, Aa2 is the average value of the amplitude of the interference signal branch, and F is the index value of the main frequency of the final vortex signal, then the step (4) includes the steps: (4.1) Compare the maximum value of the harmonic amplitude of the two detection signals. If A1<A2, it means that the measurement is abnormal and is illegal data. The vortex flowmeter will give an abnormal warning and give up the measurement result this time; if A1≧A2 , go to the next step; (4.2) Determine whether the maximum harmonic amplitude values A1 and A2 of the two detection signals are equal. If they are equal, continue to compare the average amplitude values of the two harmonics. If Aa1=Aa2, it can be judged that the vortex street signal branch is Empty tube, end; if Aa1≠Aa2, reset the amplitudes of the spectral lines corresponding to F1 and F2 to zero, and return to step (4.1); if A1>A2, proceed to the next step; (4.3) Compare F1 and F2, if F1≧F2, then judge the frequency index value of the vortex signal to be F1; otherwise, it means that the measurement is abnormal, which is illegal data, and the vortex flowmeter will issue an abnormal warning and give up the measurement result this time .

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