Intelligent frequency conversion, current transform type excitation electromagnetic flow meter

Abstract

The method of excitation utilizes the continuous adjustable exciting current with frequency conversion and variable current as well as the optimized frequency and intensity of the exciting current obtained by using the optimizing algorithm at the calibration. The communication pin of the meter processor in the flowmeter is conencted to the pins of the communication module, PC, the excitation circuit, the excitation coil and measuring pole, the sampling hold circuit, the differential amplification and D / A converter etc. The pins of the meter processor through the photoelectric circuit are connected to the output circuit of the standard signal. The display is directly connected to the pins of the meter processor. The invention makes the excitation output signal of the electromagnetic flowmeter change corresponding to the change of the input signal measured.

Description

technical field [0001] The invention relates to an intelligent frequency conversion and variable flow excitation electromagnetic flowmeter. Background technique [0002] Electromagnetic flowmeter is an instrument that measures the volume flow of conductive liquid by Faraday's law of electromagnetic induction. [0003] According to Faraday's law of electromagnetic induction, when a conductor moves in a direction perpendicular to the magnetic field under a uniform magnetic field, the induced electromotive force is: [0004] U=Hdv (1) [0005] In the formula U - induced potential; [0006] H - magnetic field strength; [0007] d - conductor width; [0008] v - the velocity of the conductor. [0009] Let the flow rate of conductive fluid in the pipe with inner diameter d be q v , [0010] but: [0011] q v = vπ ( d 2 ...

AI Technical Summary

Problems solved by technology

The flow rate of the liquid to be measured is constantly changing, and although the diameter of the pipe does not change for the same meter, in the excitation mode 1, the frequency and amplitude of the excitation current do not change due to the different diameters of the meter. In the excitation mode 2, although there is a change, it is not a continuous change. In the excitation mode 3, it is played by human experience, and the instrument is not continuous intelligent frequency conversion or variable current excitation.

[0021] Therefore, when multiple factors affecting the measured signal are changing, the disadvantages of the traditional excitation method are obvious.

The instrument cannot automatically make corresponding changes according to changes in the measurement conditions, and it is difficult to obtain more accurate measurement results

This is not obvious in small-caliber instruments, but it is more obvious in large-caliber instruments, such as: serious zero drift, unstable readings, large jumping range of measured values, difficult calibration, etc.

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