Reduced noise sensitivity in magnetic flowmeter
AssigneeRosemount Inc.
InventorsScot R. Foss, Kirk A. Hunter
Life of this patent
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Abstract
A magnetic flowmeter for measuring flow of a process fluid includes a coil configured to apply a magnetic field to the process fluid. Electrodes are arranged to sense a fluid voltage signal related to the applied magnetic field and fluid flow. An analog to digital converter provides a digital output comprising a plurality of digital samples related to the sensed fluid voltage signal. Computation circuitry receives the digitized samples and responsively provides an output related to flow.
Claims17
A magnetic flowmeter for measuring flow of a process fluid, comprising:
- a coil configured to apply a magnetic field to the process fluid;
- a coil driver configured to apply a coil drive signal to the coil;
- electrodes arranged to sense a fluid voltage signal related to the applied magnetic field and fluid flow;
- an analog to digital converter having a digital output comprising a plurality of digital samples related to the sensed fluid voltage signal;
- digital computation circuitry configured to receive the digitized samples, filter the samples in accordance with a non-linear filter implemented in software, and responsively provide an output related to flow;
- wherein the digital computation circuitry inverts at least a portion of the digitized sensed fluid signal;
- and
- the portion comprises a trailing portion of a half cycle of the fluid voltage signal.
A magnetic flowmeter for measuring flow of a process fluid, comprising:
- a coil configured to apply a magnetic field to the process fluid;
- a coil driver configured to apply a coil drive signal to the coil;
- electrodes arranged to sense a fluid voltage signal related to the applied magnetic field and fluid flow;
- an analog to digital converter having a digital output comprising a plurality of digital samples related to the sensed fluid voltage signal;
- computation circuitry configured to receive the digitized samples and provide an output related to flow by inverting using software at least a portion of the digitized sensed fluid voltage signal;
- and
- the portion comprises a trailing portion of a half cycle of the fluid voltage signal.
A method for measuring flow in a process fluid, comprising:
- applying a coil drive signal to a coil proximate the process fluid and thereby applying a magnetic field to the process fluid;
- sensing a fluid voltage signal in the process fluid related to the applied magnetic field and to fluid flow;
- digitizing samples of the voltage signal;
- digitally filtering samples of the digitized voltage signal using a non-linear filter implemented in software;
- including inverting at least a portion of the digitized sensed fluid flow signal;
- the portion comprising a trailing portion of a half cycle of the fluid voltage signal;
- and outputting flow based upon the filtered samples.
Dependencies are inferred from the claim text.