A signal processing method for 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 high-frequency sine wave excitation electromagnetic flowmeter, when the pipeline is at zero flow velocity, the output signal of the sensor is subjected to quadrature demodulation processing to obtain the phase parameter of the differential interference component, and then the excitation is adjusted according to the obtained phase parameter value. Phase adjustment of the current signal. In the actual flow measurement, the excitation current signal after phase adjustment is used as the reference signal. The reference signal is used to demodulate the flow signal, and the calculation result containing only the flow information can be obtained, the differential interference can be suppressed, and the zero point output of the system can be reduced. Based on the signal processing method, a software system based on DSP is developed to process the flow signal in real time. The software system includes a main monitoring program, an initialization module, an interrupt module, a human-computer 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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