Vortex street flowmeter signal digital processing system based on MCU (Microprogrammed Control Unit)

Abstract

The invention relates to a vortex street flowmeter signal digital processing system based on an MCU (Microprogrammed Control Unit), characterized in that after a detected charge signal detected by a sensor (1) is preprocessed by a signal preprocessing part (2), a time domain voltage signal is converted into a frequency domain signal after converted by an FFT (Fast Fourier Transform Algorithm); detailing and frequency spectrum correction are carried out on a frequency range in which vortex street signals are possibly located through an MCU control chip and a control circuit part (3) thereof; the vortex street signals mixed in sensor signals are identified through an MCU software processing part (5) by utilizing an amplitude-frequency characteristic curve for the vortex street signals; and signal modulation is input to a modulating signal output part (4) through the signal processing arithmetic of the software of the MCU software processing part (5). The invention adopts a universal lower-power consumption singlechip to realize the digital signal processing arithmetic; by adopting an amplitude-frequency windage analysis (AFWA) technology, the field application anti-vibration property of the meter is improved, the lower limit of flow is expanded, and the measurement range ratio is broadened and can reach 1:36; and when a measurement medium is water, the minimum measurable flow rate can reach 0.2m / s. The system has small size, low cost, lower power consumption and complete functions.

Description

Technical field: [0001] The invention relates to an MCU-based signal digital processing system of a vortex flowmeter. Background technique: [0002] The vortex flowmeter uses the principle of the Kalman vortex street in fluid mechanics, according to the characteristic that the frequency of the sensor output signal is proportional to the flow velocity within a certain range of flow velocity, and measures the frequency of the sensor output signal through various forms of detection elements. The volumetric flow rate of the fluid. The stress-type vortex flowmeter generally places the stress sensing element downstream of the generating body to detect the lateral alternating lift force of the vortex street, and converts this alternating force into a charge signal for measurement. However, domestic manufacturers generally use analog signal processing methods. This method has a simple circuit structure and short development cycle, and the signal output response speed is fast, but t...

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Problems solved by technology

[0003] At present, the method of digital signal processing for vortex street signals is generally to directly and simply perform frequency domain transformation or digital filtering algorithm on vortex street signals, which has obvious effects on sensor signals with high signal-to-noise ratio, especially to solve the problem of random vibration interference. It overcomes some disadvantages of analog signal processing and improves stability, but there are various complex signal interferences in practical applications, such as power frequency vibration interference and electromagnetic interference signals that are common in working conditions, and its signal-to-noise ratio is low Directly using simple spectrum analysis at 0dB will not get good results, so the lower limit of the measurable flow velocity often depends on the strength of the periodic interference signal, and the stability is limited

Secondly, the digital signal processing technology is used for the vortex street signal. Under the premise of meeting the measurement accuracy, the microprocessor needs a lot of calculations, otherwise the real-time performance of the measurement cannot be satisfied. At present, DSP chips with fast calculation speed are generally used, such as Chinese patent 200510041058.1, etc. , but its high power consumption cannot meet the requirements of the two-wire system of industrial instruments, so this problem needs to be solved from two aspects

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