Fault detection method for electromagnetic flowmeter

Excitation electromagnetic flowmeter fault detection method, research and development of electromagnetic flowmeter automatic control system, is put forward based on the linear power supply design of constant current source circuit, and adopts high pressure source incentive improves the performance of the system has rapid response, according to the design of H bridge driving circuit for waveform excitation coil, design flow circuit to keep the excitation current of accurate detection, according to the design of DSP excitation timing circuit to keep single frequency or single frequency excitation.

The experiment shows that the excitation automatic control system can maintain accurate high frequency or single frequency excitation and ensure that the output data signal of the electromagnetic flowmeter has a stable 0 point, thus laying a foundation for improving its measurement rate and precision.

At present, the electromagnetic flowmeter in China basically adopts the low-frequency square wave excitation mode to obtain the stable zero point.However, according to Faraday's law of electromagnetic induction, the electromagnetic flowmeter cannot realize fast measurement and ensure the accuracy of slurry measurement by excitation.

For the magnetic coil to apply the magnetic field to the measured body, so as to detect the magnetic field, high frequency excitation and dual-frequency excitation methods are proposed abroad. For example, the induction electromotive force of the moving fluid in Japan is used to measure the volume of the conductive liquid. The dual-frequency electromagnetic flowmeter of yokogawa and the high-frequency electromagnetic flowmeter of Toshiba are proposed.

However, in the case of high frequency excitation (there is also high frequency excitation in dual-frequency excitation), due to the inductive load characteristics of the excitation coil, the excitation current can hardly reach steady state in the excitation half cycle, which makes it difficult for the signal to obtain stable zero.Therefore, the fast response characteristic of constant current control is the focus of high frequency excitation control system design.At the same time, accurate detection of excitation current and accurate control of excitation frequency are the preconditions for obtaining high precision signal processing results.However, foreign companies do not disclose the details of these key technologies.

Aimed at the rapidity of constant current control, the excitation current of accuracy and precision of the excitation frequency control, the purpose of the constant current control circuit based on the linear power supply design, and USES the high voltage source motivation, make it has a fast response performance, based on the H bridge driving circuit design realization of square wave excitation, the H bridge between low-end and to access galvanometer circuit, and through the control the flow of H bridge works to realize accurate inspection with peripheral devices design based on DSP excitation circuit realization of single frequency and dual-frequency precise excitation sequence.

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