Method for operating a magnetic inductive flowmeter and magnetic inductive flowmeter

Patent metadata

Field	Value
Publication number	US-11313708-B2
Application number	US-201816954028-A
Country	US
Kind code	B2
Filing date	Nov 14, 2018
Priority date	Dec 14, 2017
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

The present disclosure relates to a method for operating a magnetoinductive flowmeter in which, during a constant phase having a constant magnetic field, a plurality of raw measured values of the raw measurement voltage are determined, the raw measurement voltage including a flow-dependent component, an interference component and a noise component, wherein each raw measured value assigned a flow measured value and an interference voltage value, wherein a raw measured value from a preceding first constant phase and a raw measured value from a second constant phase following the first constant phase are used to calculate a second flow measured value and a second interference voltage value of the interference component, wherein first flow measured values from the first constant phase and/or second constant phase are corrected using the knowledge of the second flow measured value and the calculated second interference voltage value.

First claim

The invention claimed is:

1. A method for operating a magnetic inductive flow meter for measuring the volumetric flow or the flow rate of a medium flowing through a measuring tube of the flow meter, the method comprising:
providing a magnetic inductive flow meter comprising:
a magnet system configured to generate a magnetic field;
a measuring tube having a measuring tube axis;
at least one pair of measuring electrodes, including a first measuring electrode and a second measuring electrode; and
an electronic measuring/operating circuit configured to evaluate raw measurement voltages and to determine flow measurement values, the measuring/operating circuit electrically connected to the at least one pair of measuring electrodes;

applying a magnetic field to a medium flowing thorough the measuring tube, the magnetic field perpendicular to the measuring tube axis;
generating a magnetic field curve having constant phases, during which the magnetic field is constant over time, and alternating phases during which the magnetic field is variable over time, the alternating phases configured to change from a first constant phase having a first magnetic field into a subsequent, second constant phase having a second magnetic field, the second magnetic field being dissimilar from the first magnetic field;
tapping a flow-dependent, electric raw measurement voltage induced in the medium by the magnetic field using the at least one pair of measuring electrodes;
determining a plurality of raw measurement values of the raw measurement voltage during each constant phase using the measuring/operating circuit, the raw measurement voltage comprising a flow-dependent component, an interference component and a noise component;
calculating from each raw measurement value a first flow measurement value and a first interference voltage value from each raw measurement value using the measuring/operating circuit;
calculating a second flow measurement value and a second interference voltage value of the interference component based on a raw measurement value of a preceding first constant phase and a raw measurement value of a second constant phase following the first constant phase using the measuring/operating circuit; and
adapting the first flow measurement values of the first constant phase and/or second constant phase based on the second flow measurement value and the calculated second interference voltage value using the measuring/operating circuit.

2. The method of claim 1 , further comprising:
predicting a subsequent forecast value of the flow based on the first flow measurement value;
predicting a subsequent forecast value of the interference voltage based on the first interference voltage value;
measuring a further raw measurement value;
calculating a first flow measurement value based on the forecast value of the flow and the further raw measurement value;
calculating a further first interference voltage value based on the forecast value of the interference voltage and the further raw measurement value; and
repeating the method to determine further first flow measurement values and further first interference voltage values.

3. The method of claim 2 , wherein a weighting of the forecast values of the flow and of the interference voltage and of the raw measurement value are flow dependent.

4. The method of claim 2 , wherein the predicting of the forecast values of the flow and of the interference voltage is based on linear or quadratic continuation or on Taylor expansion.

5. The method of claim 2 , wherein a first variance is assigned to the forecast value of the flow, a second variance is assigned to the forecast value of the interference voltage, and a third variance is assigned to the raw measurement value, and
wherein the calculating of the first flow measurement value or the first interference voltage value is based on the associated first, second and/or third variances using a weighting of the respective forecast value and of the raw measurement value.

6. The method of claim 5 , wherein an estimation of each of the first, second and third variances is based on a difference between the corresponding forecast value of the flow or interference voltage and the raw measurement value or a signal-to-noise ratio.

7. The method of claim 5 , wherein the occurrence of at least one of the following criteria prompts an alternating phase:
the first variance exceeds a first threshold;
the second variance exceeds a second threshold;
the third variance exceeds a third threshold; and
a deviation of a forecast interference component from a first interference value exceeds a fourth threshold value.

8. The method of claim 2 , wherein a Kalman filter is used in the calculation of the forecast values of the flow and interference voltage and in the calculation of the first flow measurement value and of the first interference voltage value.

9. The method of claim 1 , wherein:
at least two flow-dependent electric raw measurement voltages induced in the medium are tapped;
curves of the raw measurement voltages are compared;
a change in the raw measurement voltage is interpreted as interference when the raw measurement voltage curve changes in the absence of a corresponding change in the respective at least one other raw measurement voltage curve; and
a change in the raw measurement voltage is interpreted as a change in the flow when the raw measurement voltage curves are essentially constant.

10. The method of claim 9 , wherein:
a first comparison voltage is tapped between the first measuring electrode and a ground and a second comparison voltage is tapped between the second measuring electrode and the ground;
the ground is a ground electrode or a pipe connected to the measuring tube or a grounding disk; and/or
a flow-dependent electric raw measurement voltage is tapped using at least two pairs of measuring electrodes.

11. The method of claim 9 , wherein the comparing of the raw measurement voltages is performed based on the raw measurement voltages or first flow measurement values derived therefrom or second flow measurement values and/or first interference voltage values or second interference voltage values.

12. The method of claim 1 , wherein at least two raw measurement values of the raw measurement voltage are determined during each constant phase.

13. The method of claim 1 , wherein each raw measurement value is calculated by averaging a plurality of tapped raw measurement voltages, the averaging including at least two and/or no more than 100 tapped raw measurement voltages.

14. The method of claim 1 , wherein:
the magnetic field is at least partially generated by at least one remanence magnet during the constant phases, and wherein, during the alternating phases, a remanent field of the remanence magnet is changed by reversing a polarity thereof using a coil system including at least one coil; or
the magnetic field is at least partially generated by at least one permanent magnet or at least partially by a coil system, including at least one coil, during the constant phases, and wherein, during the alternating phases, the magnetic field is changed by changing the magnetic field component generated by the coil system; or
the magnetic field is generated by a coil system including at least one coil.

15. A magnetic inductive flow meter configured for measuring the volumetric flow or the flow rate of a medium flowing through the flow meter, the flow meter comprising:
a measuring tube having a measuring tube axis and configured to guide the flowing medium therethrough;
a magnet system configured to generate a magne

Assignees

• Flowtec Ag

Inventors

• Linnert Michael
• Mariager Simon

Classifications

• G01F1/588

  combined constructions of electrodes, coils or magnetic circuits, accessories therefor · CPC title

• G01F1/60 Primary

  Circuits therefor · CPC title