CN104266693A - Electromagnetic flowmeter measurement system - Google Patents

Abstract

The present invention discloses an electromagnetic flowmeter measurement system, comprising: an excitation coil, an excitation device, electrodes, a signal processing circuit, an A/D converter, a flow value calculation device, and a flow value output device. The excitation device of the present invention provides a rectangular excitation current to the excitation coil in at least two excitation cycles, and selectively converts multiple excitation cycles to obtain initial flow signals of multiple excitation frequencies, which can effectively eliminate measurement errors caused by induced noise without performing zero-point adjustment that causes fluid flow to stop, and improves measurement accuracy and has high reliability.

Description

Electromagnetic flowmeter measurement system

technical field

The invention relates to an electromagnetic flowmeter measuring system.

Background technique

The weight function of the electromagnetic flowmeter is a fictitious physical quantity. Its physical meaning is: when the electromagnetic flowmeter is working, it measures the contribution of the induced electromotive force generated by each point in the pipe space to the output voltage between the electrodes. Scientists have made a clear definition of the numerical value of the weight function of a certain point in the pipe space measured by the electromagnetic flowmeter, that is, when the unit current flows through two electrodes to form a current loop, the current density of the point. Therefore, there are also many literatures that call the weight function virtual current, and the measurement system of the electromagnetic flowmeter is used to calculate the flow through this current, but the current measurement system is difficult to eliminate the measurement error caused by the induced noise, and the reliability is low .

Contents of the invention

In order to overcome the deficiencies of the prior art, the invention provides an electromagnetic flowmeter measuring system.

The technical solution adopted by the present invention to solve its technical problems is:

Electromagnetic flowmeter measurement system, including:

Exciting coils arranged on the upper and lower sides of the measuring tube, the exciting coils provide a magnetic field to the inside of the measuring tube;

An excitation device, the excitation device is connected to the excitation coil, and provides a rectangular excitation current to the excitation coil with at least two excitation cycles;

An electrode, which is arranged on the left and right sides of the measuring pipe, is used to detect the current generated by cutting the magnetic field line by the flow in the measuring pipe;

a signal processing circuit, the signal processing circuit is connected to the electrodes and is used to process the current signals detected by the electrodes;

an A/D converter connected to a signal processing circuit for converting an analog signal into a digital signal;

flow value calculation means, which is connected to the A/D converter, and is used to generate an electromotive force between the electrodes in each of the excitation periods, based on the electromotive force generated during the excitation period. Pushing the flow signal so as to obtain the flow value signal that will be obtained when the excitation period is infinite;

The flow value output means, the flow value output means and the flow value calculation means are used to output the flow value signal obtained by means of the flow value calculation means by extrapolation.

The flow value calculation device performs extrapolation calculation according to the linear function of the excitation period.

The rectangular excitation current is selectively switched in three excitation cycles, wherein the flow value calculation device obtains flow value signals from the flow signals of the three excitation cycles.

The signal processing circuit includes an amplifier circuit and a filter circuit, and the signal is output after passing through the amplifier circuit and the filter circuit in sequence.

The flow value calculating device is a microprocessor.

The flow value output device is a display.

The beneficial effects of the present invention are: at least two excitation cycles of the excitation device of the present invention provide a rectangular excitation current to the excitation coil, and selectively switch multiple excitation cycles, so that initial flow signals of multiple excitation frequencies can be obtained, The measurement error caused by the induction noise can be effectively eliminated without zero point adjustment causing fluid flow to be stopped and the measurement accuracy is improved with high reliability.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of the structure of the present invention.

Detailed ways

Referring to Fig. 1, Fig. 1 is a schematic structural diagram of a specific embodiment of the present invention, as shown in the figure, the electromagnetic flowmeter measuring system includes:

The excitation coil 2 arranged on the upper and lower sides of the measuring tube, the exciting coil 2 provides a magnetic field to the inside of the measuring tube;

An excitation device, the excitation device is connected to the excitation coil, and provides a rectangular excitation current to the excitation coil with at least two excitation cycles;

Electrode 1, the electrode 1 is arranged on the left and right sides of the measuring pipe fitting, and is used to detect the current generated by cutting the magnetic force line of the flow in the measuring pipe fitting;

A signal processing circuit, the signal processing circuit is connected to the electrode 1, and is used to process the current signal detected by the electrode 1;

an A/D converter connected to a signal processing circuit for converting an analog signal into a digital signal;

flow value calculation means, which is connected to the A/D converter, and is used to generate an electromotive force between the electrodes in each of the excitation periods, based on the electromotive force generated during the excitation period. Pushing the flow signal so as to obtain the flow value signal that will be obtained when the excitation period is infinite;

The flow value output means, the flow value output means and the flow value calculation means are used to output the flow value signal obtained by means of the flow value calculation means by extrapolation.

Preferably, the rectangular excitation current is selectively switched in three excitation cycles, wherein the flow value calculation device obtains the flow value signal from the flow signals of the three excitation cycles, and the flow value calculation device obtains the flow value signal according to the excitation cycle The linear function of the linear function is extrapolated. Since the initial flow signals of the three excitation frequencies can be obtained, the measurement error caused by the induction noise can be effectively eliminated, and the zero point adjustment that causes the stop of the fluid flow is not performed, and the measurement accuracy is improved, and it is reliable. high sex.

Further, the signal processing circuit includes an amplifier circuit and a filter circuit, and the signal is output after passing through the amplifier circuit and the filter circuit in sequence, that is, the filter circuit filters the output of the signal amplifier circuit to reduce the influence of interference noise and obtain the fundamental wave of the flow velocity signal, And make the power of various interference noises decrease as the bandwidth decreases, improve the signal-to-noise ratio, and improve the measurement accuracy of the electromagnetic flowmeter.

Preferably, the flow value calculation device is a microprocessor, and the flow value output device is a display, and the microprocessor is preferably an MSP430 single-chip microcomputer of Hong Kong TI Company or an 80C552 single-chip microcomputer of Netherlands PHILIPS company.

The preferred implementation of the present invention has been described in detail above. Of course, the present invention can also adopt different forms from the above-mentioned embodiments. Those skilled in the art can make equivalent transformations or corresponding equivalents without violating the spirit of the present invention. Any changes should fall within the protection scope of the present invention.

Claims (6)

1. electromagnetic flowmeter survey system, is characterized in that: comprising:

Be arranged on the magnetizing coil (2) measuring the upper and lower both sides of pipe fitting, this magnetizing coil (2) provides magnetic field to described measuring tube inside;

Magnetizer, this magnetizer is connected with magnetizing coil, and provides rectangle exciting curent with the excitation cycle of at least two to described magnetizing coil;

Electrode (1), this electrode (1) is arranged on measures the pipe fitting left and right sides, the electric current produced for detecting flow cutting magnetic line in measurement pipe fitting;

Signal processing circuit, this signal processing circuit is connected with electrode (1), for the treatment of the current signal detected by electrode (1);

A/D converter, this A/D converter is connected with signal processing circuit, for being digital signal by analog-signal transitions;

Flow value calculation element, this flow value calculation element is connected with A/D converter, when being used for producing electromotive force in excitation cycle when between described electrode often kind described, according to the described electromotive force extrapolation flow signal produced during described excitation cycle, to obtain the flow value signal that will obtain when described excitation cycle is infinity;

Flow value output unit, this flow value output unit and flow value calculation element, be used for exporting the described flow value signal obtained by means of described flow value calculation element by extrapolation method.

2. electromagnetic flowmeter survey system according to claim 1, is characterized in that: described flow value calculation element carries out extrapolation computing according to the linear function of excitation cycle.

3. electromagnetic flowmeter survey system according to claim 1, it is characterized in that: described rectangle exciting curent is selectivity conversion in three excitation cycles, and wherein said flow value calculation element obtains flow value signal from the flow signal of described three excitation cycles.

4. electromagnetic flowmeter survey system according to claim 1, it is characterized in that: described signal processing circuit comprises amplifying circuit, filtering circuit, signal exports successively after amplifying circuit, filtering circuit.

5. electromagnetic flowmeter survey system according to claim 1, is characterized in that: described flow value calculation element is a microprocessor.

6. electromagnetic flowmeter survey system according to claim 1, is characterized in that: described flow value output unit is a display.