Signal processing method of high-frequency sine wave excitation electromagnetic flowmeter

Abstract

The invention relates to a signal processing method of a high-frequency sine wave excitation electromagnetic flowmeter. Aiming at the problem of large differential interference of a high-frequency sine wave excitation electromagnetic flowmeter, orthogonal demodulation processing is carried out on a sensor output signal at a zero flow rate of a pipeline to obtain a phase parameter of a differentialinterference component, and then phase adjustment is carried out on an exciting current signal according to the obtained phase parameter value. During actual flow measurement, the phase-adjusted exciting current signal is used as a reference signal; and when the reference signal is used for demodulating a flow signal, a calculation result only containing flow information can be obtained, differential interference is inhibited, and zero output of the system is reduced. Based on the signal processing method, a software system based on a DSP is developed, and flow signals are processed in real time. The software system comprises a main monitoring program, an initialization module, an interruption module, a man-machine interaction module, a watchdog module and a signal processing module.

Description

technical field [0001] The invention belongs to the technical field of flow detection, and more specifically, relates to a signal processing method of a high-frequency sine wave excitation electromagnetic flowmeter. Background technique [0002] Electromagnetic flowmeter is based on the principle of Faraday's electromagnetic induction. It measures the volumetric flow by measuring the induced electromotive force generated by cutting the magnetic force lines when the conductive liquid flows through the pipeline covered by the magnetic field. It is widely used in chemical industry, metallurgy and papermaking and other industries. After a long period of development, electromagnetic flowmeters have been greatly improved in terms of excitation methods and signal processing methods. In order to reduce the influence of the polarization interference caused by the electrochemical effect of the electromagnetic flowmeter, the excitation method has developed from the past DC excitation t...

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Problems solved by technology

However, this process of obtaining the phase value of the reference signal has poor applicability, the implementation process is complicated, and no specific phase adjustment method is given.

In the existing patent "A method for detecting electromagnetic flow signals" (Yang Hongyu, Zhao Hui, Xiao Xiao, Kang Bo, Chen Zijian, Wang Bingfeng, invention patent, 201410325869.3, application date: 2014.07.08, application publication date: 2014.09.24) A sine wave signal processing method based on cross-correlation is proposed to overcome the differential interference of the same frequency and the same-phase interference, but the cross-correlation operation is complicated and requires a long time integral operation, which reduces the real-time performance of the operation

The existing patent "Scalable and continuous auto-zeroing method for AC driven magneto-inductive flowmeters" (Scherrer Rémy, FleckenPeter, Tschambser Florent, invention patent, 12194283.3, application date: 2012.11.26, application publication date: 2014.05.28) adopts double The method of frequency excitation automatically compensates the fluctuation of the zero point by analyzing the signal output by the sensor electrode during dual-frequency excitation, but the implementation of dual-frequency excitation is relatively complicated, and the patent does not give a specific implementation method

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