Method for tracking and estimating high-precision frequency of coriolis mass flowmeter
A mass flow meter and frequency tracking technology, applied in the direction of direct mass flow meter, mass flow measurement device, measurement flow/mass flow, etc., can solve the problems of poor real-time tracking frequency effect, complex algorithm design and large amount of calculation, etc. Achieve the effect of improving the digital signal processing system
Inactive Publication Date: 2017-05-10
NORTHWESTERN POLYTECHNICAL UNIV
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This patent uses FIR filter to realize its described function, and requires the center frequency to be fixed. If the method described in this patent is used to realize CMF high-precision frequency estimation, the problem to be faced is to solve the problem of covering all CMF devices described in it. The design of this algorithm is complicated. Although it can stabilize the filter characteristics, it needs to pay a large amount of computing space and computing time. It uses the least square method to decompose the signal harmonically. Affected by non-integer cycle truncation, but this method is computationally intensive, and the effect of real-time tracking frequency is not good
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[0052] Step 1. For four general-purpose series of CMF flow tubes produced by a domestic manufacturer, the CMF signal output frequency ranges from 40-240Hz. The CMF primary instrument output signal frequency includes various high frequencies in addition to the resonance frequency. In addition, the resonance frequency of the signal output by CMF is also related to the nature, flow velocity and density state of the fluid. When the flow tube is in the state of two-phase flow or batch material flow, the natural frequency and damping ratio of the flow tube will occur. When processing the signal output by the CMF primary instrument, the signal needs to be preprocessed. The present invention uses a low-pass filter to filter out the high-frequency noise of the output signal of the CMF primary instrument. The analog low-pass filter technical index that the present invention uses is determined as: passband cut-off frequency Ω p =400Hz, the maximum attenuation α in the passband p =3dB, s...
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The invention provides a method for tracking and estimating high-precision frequency of a coriolis mass flowmeter, and relates to the field of digital signal processing. An improved segmentation phase difference frequency estimation method is adopted for resolving output signals of the coriolis mass flowmeter to obtain the instantaneous frequency related to fluid flow mass and density. A digital signal processing method is adopted for estimating CMF resonance frequency, is not affected by simulation circuit time delay and RLC parameters, and has the advantages of being flexible and high in speed and precision, no complex algorithm for self-adaptation linear enhance signals and the like needs to be adopted, the processed data complexity is obviously improved compared with a coriolis mass flowmeter digital signal processing system based on AFF and SGA, and it is correctly and stably tracked that the CMF output frequency precision reaches 99.999%.
Description
technical field [0001] The invention relates to the field of digital signal processing, in particular to a frequency tracking and estimation method of a Coriolis mass flow meter. Background technique [0002] Coriolis Mass Flowmeter (Coriolis Mass Flowmeter, CMF) is based on the principle of resonance and the Coriolis effect (the principle of Coriolis force proportional to the mass flow when the fluid moves in a straight line), and can High-end instrumentation for accurate measurement of fluid flow quality with excellent measurement accuracy and reliability. At present, most of the CMFs sold in the domestic market adopt analog drive mode and analog signal processing method, which are easily affected by external vibration and unstable fluid flow rate, which makes the accuracy of mass flow measurement on the industrial site lower than the accuracy calibrated in the experiment. The driving and processing method of the analog circuit is to filter and detect the zero-crossing po...
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CPCG01F1/8436
Inventor 李京华黄熠彬司君国杨昭杰
Owner NORTHWESTERN POLYTECHNICAL UNIV