A Method of Amplitude Control for Coriolis Mass Flowmeter

Abstract

The invention provides a Coriolis mass flowmeter (CMF) amplitude control method, and relates to the field of fluid measurement. The method comprises: sampling a flow tube start-up signal and subjecting the signal and a preset value to subtraction to obtain a difference value; then forming a controlled quantity by means of linear combination to perform amplitude control on the flow tube, and calculating a group of optimal control parameter values by using a PID parameters setting method based on amplitude margin so as to achieve the optimal parameter setting for a closed-loop system. The method, by optimizing the amplitude response sensitivity range of the flow tube and improving the sampling period of a discretization system, determines an amplitude adjustment objective function, overcomes oversaturation amplitude out of control caused by a short-term increase in the start-up amplitude output, improves amplitude response speed, optimizes amplitude tracking performance by using a digital signal processing mode, ensures high-precision frequency and phase difference output, uses few hardware resources, does not require complex core circuit design, and reduces business use cost.

Description

technical field [0001] The invention relates to the field of fluid measurement, in particular to a control method for a Coriolis mass flowmeter. Background technique [0002] Coriolis mass flowmeter (Coriolis Mass Flowmeter, CMF) is widely used in the field of mass flow measurement of liquid media such as petroleum and petrochemical, food and medicine, due to its advantages of high measurement accuracy, low maintenance cost and the ability to realize multi-parameter measurement. In the case of small-flow gas and liquid two-phase flow / batch material flow that are often encountered in the field of fluid measurement, the analog circuit-driven CMF method currently used in China has slow response speed, poor performance in dynamic tracking of vibration tube amplitude changes, and limited gain output range. There are many shortcomings such as the limit, which leads to the failure of the flow tube vibration control and the decrease of measurement accuracy, and it is impossible to m...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the FPGA-driven closed-loop system needs to be redesigned to meet the expected set indicators when corresponding to different tube types of CMF. The FPGA core digital signal processing circuit should include a digital filter, a signal detector, a phase There are seven parts including controller, amplitude controller, sinusoidal signal generator, FIFO component and clock module. The core structure is complex and the cost of use is very high.

[0003] To sum up, the traditional analog circuit driving amplitude control method used by Coriolis mass flowmeters cannot meet the measurement accuracy of liquid mass flow in the case of small flow two-phase flow / batch flow. The defect of poor performance in tracking the change of the vibration amplitude of the flow tube can also easily lead to the phenomenon of stop vibration or excessive oscillation of the CMF flow tube, while the CMF digital closed-loop control system implemented by FPGA hardware circuit has complex system, difficult design and high cost of use. The problem is that it cannot be applied to all CMF tube types

Images