Method for performing temperature compensation of maximum sensor current and test tone amplitude during meter verification
AssigneeMicro Motion, Inc.
InventorsTimothy J. Cunningham, Miles Keeney-Ritchie
Life of this patent
Estimating the term…
Abstract
A method of determining optimal resistance and compensating for temperature variations in determining a test tone is presented. The optimal resistance in a drive circuit amplifier and drive coil and using the optimal resistance to improve the accuracy of a test tone used in the calibration of a flow meter is presented. The optimal resistance is calculated using a linear extrapolation of the resistance change of the circuit with respect to temperature. The optimal resistance is then used to calculate the proper maximum sensor current (MSC) value using an equation derived from Ohm's law, and from the MSC a test tone level is calculated.
Claims19
A method for determining and employing a test tone level during a meter verification of a vibrating flow meter, the method comprising:
- calculating an electrical resistance of a coil wire of a driver, the coil wire receiving a plurality of drive currents to test an integrity of flow tubes of the vibrating flow meter;
- calculating a maximum sensor current (MSC) using the electrical resistance, the maximum sensor current (MSC) being the maximum current a drive amplifier can deliver to the coil wire;
- measuring the plurality of drive currents during an appropriate period of time;
- averaging the plurality of drive currents;
- calculating a buffer value using the average of the plurality of drive currents;
- calculating the test tone level of a test tone on either side of a drive frequency of the vibrating flow tubes using the maximum sensor current (MSC) and the buffer value;
- and
- operating the vibrating flow meter at the test tone level calculated during meter verification, the test tone level being within a range that avoids voltage clipping, thereby reducing stiffness uncertainty in the vibrating flow meter.
A method of performing temperature compensation of a test tone amplitude during meter verification in a vibrating flow meter with a test tone level, comprising:
- calculating an electrical resistance using one of a curve-fit of test data and the known resistance change of a coil wire of a driver with temperature, the coil wire receiving a plurality of drive currents to test an integrity of a flow tube of the vibrating flow meter;
- calculating a maximum sensor current (MSC) using the electrical resistance, maximum voltage and an EMF voltage, the maximum sensor current (MSC) being the maximum current a drive amplifier can deliver to the coil wire;
- measuring the plurality of drive currents for an appropriate period of time;
- averaging the plurality of drive currents;
- calculating a buffer value using the average of the drive currents;
- calculating the test tone level of a test tone on either side of a drive frequency of the vibrating flow tubes using the maximum sensor current (MSC) and the buffer value;
- and
- operating the vibrating flow meter at the test tone level calculated during meter verification, the test tone level being within a range that avoids voltage clipping, thereby reducing stiffness uncertainty in the vibrating flow meter.
A meter electronics for dynamically optimizing maximum sensor current in a vibrating flow meter with a test tone level, comprising:
- an interface for receiving a plurality of temperature values and corresponding electrical resistance values, sensor current, maximum voltage, EMF voltage and drive currents;
- a storage system for storing and retrieving the plurality of temperature values and the corresponding electrical resistance values, sensor current, maximum voltage, EMF voltage and drive currents;
- and
- a processing system for measuring a plurality of drive currents to test an integrity of flow tubes of the vibrating flow meter for an appropriate period of time and for performing calculations using the interface, the calculation comprising:
- extrapolation calculations using the plurality of temperature values and the corresponding electrical resistance values and produce an optimal resistance;
- maximum sensor current calculations using the electrical resistance, a maximum voltage and an EMF voltage computed;
- averaging the plurality of drive currents;
- buffer value calculations using the average of the drive currents in the processing system;
- and
- calculation of the test tone level of a test tone on either side of a drive frequency of the vibrating flow tubes using the maximum sensor current (MSC),
- wherein the processing system is configured to operate the vibrating flow meter at the test tone level calculated during meter verification, the test tone level being within a range that avoids voltage clipping, thereby reducing stiffness uncertainty in the vibrating flow meter.
Dependencies are inferred from the claim text.