A Vibration Starting Method of Coriolis Mass Flowmeter Based on All-digital Drive Mode

A technology of mass flowmeter and driving method, which is applied in the direction of direct mass flowmeter, mass flow measurement device, measurement flow/mass flow, etc., which can solve the problems of poor flow tube state tracking performance and long start-up time, etc., to improve tracking performance and reliability, shortening the time of change, and improving the effect of vibration start-up time

Active Publication Date: 2019-04-19
NORTHWESTERN POLYTECHNICAL UNIV +1
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Problems solved by technology

[0004] In order to overcome the shortcomings of the existing technology, such as the long start-up time for driving the CMF flow tube and the poor performance of tracking the state of the flow tube, the present invention provides an all-digital drive method based on equal interval frequency sweep output square wave excitation signal to drive the start-up of the CMF flow tube. method, the method outputs a continuous frequency square wave excitation signal to drive the flow tube by sweeping at equal intervals, and uses the fundamental wave component contained in the square wave signal and other abundant odd-order sinusoidal harmonic components of different frequencies to excite the flow tube. The peak value comparison method detects the amplitude of the output signal of the flow tube. When the square wave signal of a certain frequency is close to the natural frequency of the CMF flow tube, it is detected that the output signal of the CMF flow tube has the largest amplitude. The square wave signal drives the flow tube to reach the resonance state, calls the frequency rough estimation method to estimate the frequency of the flow tube output signal, and finally uses the sine wave of the resonant frequency of the CMF flow tube obtained by rough estimation to drive the flow tube to a stable working state

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  • A Vibration Starting Method of Coriolis Mass Flowmeter Based on All-digital Drive Mode
  • A Vibration Starting Method of Coriolis Mass Flowmeter Based on All-digital Drive Mode
  • A Vibration Starting Method of Coriolis Mass Flowmeter Based on All-digital Drive Mode

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Embodiment Construction

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] Step 1. Initialize the frequency range, signal amplitude, and output duration of each frequency of the output square wave signal: the frequency range of the output square wave signal covers the resonance frequency of all types of Coriolis flow tubes, and the amplitude of the square wave signal passes through a The first-stage gain conditioning circuit composed of OPA4277 (Operational Amplifier, OPA) high-precision operational amplifier amplifies the amplitude by 15 times, and the amplitude of the square wave signal after 15 times of amplitude amplification remains unchanged, and the frequency range of the initialized square wave signal is adjusted. Sweep frequency output, the sweep frequency resolution is set to 1Hz according to the CMF flow tube start-up vibration sweep frequency bandwidth, each square wave frequency continues to output for 20ms,...

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Abstract

The invention provides a start-up method for a coriolis mass flowmeter based on a full-digital driving mode, relating to the field of fluid measurement. The method comprises the following steps: driving a flow tube by outputting square wave stimulation signals with continuous frequencies at equal intervals through sweeping frequency, utilizing fundamental components contained in square wave signals and odd sine harmonic components with different frequencies to carry out shock excitation on the flow tube, detecting the amplitude of an output signal of the flow tube through a peak value comparing method wherein the output signal amplitude of the CMF flow tube is the highest when the frequency of a certain square wave signal comes close to the inherent frequency of the CMF flow tube, capturing the square wave signal, and driving again the flow tube to reach the resonance state by the square wave signal with the above frequency, calling a frequency coarse estimation algorithm to estimate frequencies of the output signals of the flow tube; finally, driving the flow tube to reach the stable working state by sine waves of resonant frequencies of the CMF flow tube through coarse estimation. The start-up method for the coriolis mass flowmeter based on the full-digital driving mode is capable of stably capturing changed frequencies to drive the flow tube again, thereby greatly improving tracking performance and reliability of the flow tube.

Description

technical field [0001] The invention relates to the field of fluid measurement, in particular to a method for starting a vibration of a Coriolis mass flowmeter. Background technique [0002] Coriolis drive system is an important part of Coriolis mass flowmeter (Coriolis Mass Flowmeter, CMF). The phase difference between the two ends of the vibrating tube is formed, and the measurement of the mass flow is realized by detecting the phase difference. The current practical Coriolis flowmeter drive system uses analog circuits or semi-digital circuits, which are susceptible to noise interference, low measurement accuracy at low flow rates, and limited lower range limits. When the CMF is in the state of two-phase flow and batch material flow, the frequency and phase tracking performance is poor, and it may even cause the flow tube to vibrate excessively or stop, which greatly affects the improvement of CMF measurement accuracy. Xu Kejun of Hefei University of Technology and other...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01F1/84
CPCG01F1/8422
Inventor 李京华黄熠彬惠全民李博
Owner NORTHWESTERN POLYTECHNICAL UNIV
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