Start-up method for coriolis mass flowmeter based on full-digital driving mode

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...

AI Technical Summary

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 differ

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