Startup techniques for a digital flowmeter
First Claim
1. A method comprising:
- inputting a first signal at a flowmeter, the first signal corresponding to a vibration of a flowtube;
generating a second signal that is compensated for a delay of the first signal, the delay being associated with a digital element associated with the flowmeter, and wherein generating the second signal comprises buffering the first signal at a buffer, the buffer storing a first cycle and a second cycle of the first signal, selecting a value from the first cycle of the first signal, and outputting the value from the buffer; and
applying the second signal to a driver coupled to the flowtube and operable to impart motion to the flowtube.
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Accused Products
Abstract
Startup and operational techniques for a digital flowmeter are described. The techniques select an optimal mode of operation for the digital flowmeter, depending on a current environment of the flowmeter. For example, during a startup operation of the flowmeter, the mode of operation might include a random sequence mode, in which filtered, random frequencies are applied as a drive signal to a flowtube associated with the digital flowmeter. Once the flowtube reaches a resonant mode of vibration, the digital flowmeter may transition to a positive feedback mode, in which a sensor signal representing a motion of the flowtube is fed back to the flowtube as a drive signal, as part of a feedback loop. Once an oscillation of the flowtube is achieved and analyzed, a digital synthesis mode of operation may be implemented, in which the analyzed sensor signals are used to synthesize the drive signal. In either the positive feedback mode or the digital synthesis mode, the digital flowmeter may revert to a previous mode to regain stable and desired oscillation of the flowtube, such as might be required during a recovery operation associated with a disturbance to an operation of the digital flowmeter.
90 Citations
22 Claims
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1. A method comprising:
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inputting a first signal at a flowmeter, the first signal corresponding to a vibration of a flowtube; generating a second signal that is compensated for a delay of the first signal, the delay being associated with a digital element associated with the flowmeter, and wherein generating the second signal comprises buffering the first signal at a buffer, the buffer storing a first cycle and a second cycle of the first signal, selecting a value from the first cycle of the first signal, and outputting the value from the buffer; and applying the second signal to a driver coupled to the flowtube and operable to impart motion to the flowtube. - View Dependent Claims (2, 3, 4)
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5. A method comprising:
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inputting a first signal at a flowmeter, the first signal corresponding to a vibration of a flowtube; filtering the first signal to obtain a filtered signal, wherein the filtered signal substantially reduces components of the first signal having a frequency outside of a pre-determined range from a resonant frequency of the flowtube; generating a second signal that is compensated for a delay of the first signal, the delay being associated with a digital element associated with the flowmeter, and wherein compensating for the delay of the first signal comprises detecting a first pre-determined marker on the filtered signal, calculating an actual frequency of the filtered signal, based on samples associated with the filtered signal, and waiting a total wait time for outputting the second signal, based on the actual frequency; and applying the second signal to a driver coupled to the flowtube and operable to impart motion to the flowtube. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A method comprising:
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inputting a first signal at a flowmeter, the first signal corresponding to a vibration of a flowtube; generating a second signal that is compensated for a delay of the first signal, the delay being associated with a digital element associated with the flowmeter, wherein compensating for the delay of the first signal comprises inputting the second signal from an output of the flowmeter to an input of the flowmeter, comparing the second signal to the first signal to determine a phase difference between the second signal and the first signal, and outputting a revised second signal from the flowmeter that is adjusted from the second signal, based on the phase difference; and applying the second signal to a driver coupled to the flowtube and operable to impart motion to the flowtube. - View Dependent Claims (12, 13)
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14. A digital flowmeter, comprising:
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a vibratable flowtube; a sensor connected to the flowtube and operable to relay information about a motion of the flowtube by way of a sensor signal; a driver connected to the flowtube and operable to impart motion to the flowtube by way of a drive signal; and a digital control and measurement system connected to the driver and the sensor, the digital control and measurement system comprising circuitry to maintain the sensor signal and the drive signal substantially in phase with one another, the digital control and measurement system comprising; a buffer operable to store a first cycle and a second cycle of the sensor signal; and a processor operable to select a value from the first cycle of the sensor signal. - View Dependent Claims (15, 16)
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17. A digital flowmeter, comprising:
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a vibratable flowtube; a sensor connected to the flowtube and operable to relay information about a motion of the flowtube by way of a sensor signal; a driver connected to the flowtube and operable to impart motion to the flowtube by way of a drive signal; a filter operable to filter the sensor signal to obtain a filtered signal, wherein the filtered signal does not include signals having a frequency outside of a pre-determined range from a resonant frequency of the flowtube; and a digital control and measurement system connected to the driver and the sensor, the digital control and measurement system comprising circuitry to maintain the sensor signal and the drive signal substantially in phase with one another, the digital control and measurement system being further operable to; synthesize the drive signal as a sine wave, detect a first pre-determined marker on the filtered signal, calculate an actual frequency of the filtered signal, based on samples associated with the filtered signal, and wait a total wait time for outputting the second signal, based on the actual frequency. - View Dependent Claims (18, 19, 20)
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21. A digital flowmeter, comprising:
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a vibratable flowtube; a sensor connected to the flowtube and operable to relay information about a motion of the flowtube by way of a sensor signal; a driver connected to the flowtube and operable to impart motion to the flowtube by way of a drive signal; and a digital control and measurement system connected to the driver and the sensor, the digital control and measurement system comprising circuitry to maintain the sensor signal and the drive signal substantially in phase with one another, the digital control and measurement system being operable to compare the sensor signal and the drive signal, to thereby determine a phase difference therebetween, and the digital control and measurement being further operable to cause the driver to apply the drive signal with a phase altered by an amount determined by the phase difference. - View Dependent Claims (22)
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Specification