MAGNETIC FLOWMETER WITH AUTOMATIC OPERATING SETPOINT SELECTION

• US 20150177035A1
• Filed: 12/20/2013
• Published: 06/25/2015
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Rovner, Bruce D., Foss, Scot Ronald, Rogers, Steven B.
• Granted Patent: US 10,641,627 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01F 1/58 by electromagnetic flowmeters
• CPC Class Codes: G01F 1/584 constructions of electrodes, accessories therefor
• CPC Class Codes: G01F 1/60 Circuits therefor
• CPC Class Codes: G01F 25/10 of flowmeters
• CPC Class Codes: G05B 13/00 Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion G05B19/00 takes precedence
• CPC Class Codes: G06F 17/40 Data acquisition and logging for input to computer G06F3/00
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A magnetic flowmeter includes a flowtube with electrodes and field coil and a transmitter that automatically determines an operating setpoint for the magnetic flowmeter based upon sensed coil inductance, sensed coil resistance, a power rating for the transmitter, the flowtube, or both, and selected performance criteria.

Claims

1. A magnetic flowmeter comprising:

a flowtube that includes;

a pipe through which fluid flows;

a field coil mounted on the pipe; and

electrodes for sensing voltage induced by a magnetic field generated by the field coil in the fluid that flows through the tube; and

a transmitter that includes;

a coil driver for exciting the field coil; and

a processor for producing a flow measurement value as a function of the voltage sensed by the electrodes, and for controlling operation of the coil driver according to an operating setpoint determined by the processor based upon flowmeter parameters including coil resistance, coil inductance, a power rating, and a performance criteria selection.

2. The magnetic flowmeter of claim 1, wherein at least one of the coil resistance, the coil inductance, and magnetic flux density is measured by the transmitter.

3. The magnetic flowmeter of claim 1, wherein the operating setpoint includes an excitation frequency and a coil drive current.

4. The magnetic flowmeter of claim 3, wherein the operating setpoint further includes a coil drive duty cycle.

5. The magnetic flowmeter of claim 1, wherein the flowmeter parameters further include flowtube gain.

6. The magnetic flowmeter of claim 1, wherein the flowmeter parameters further include at least one of coil current, electrode noise, signal-to-noise ratio, and electrode voltage zero shift characteristics.

7. The magnetic flowmeter of claim 1, wherein the power rating comprises at least one of flowtube power rating and transmitter power rating.

8. The magnetic flowmeter of claim 1, wherein the performance criteria comprises at least one of fastest response, highest signal-to-noise ratio for a particular excitation frequency, highest-signal-to-noise ratio for a particular accuracy, and power efficiency.

9. The magnetic flowmeter of claim 1, wherein the processor continuously adjusts the operating setpoint.

10. A magnetic flowmeter comprising:

a flowtube having a coil for producing an alternating magnetic field and electrodes for sensing voltage induced by the magnetic field in fluid flowing through the tube;

a coil driver connected to the coil to produce the alternating magnetic field at a coil drive frequency and at a current setpoint, the coil driver including circuitry for sensing coil current; and

a processor that generates a flow output as a function of a sensed voltage between the electrodes, wherein the processor controls the coil driver based on a coil resistance value, a coil inductance value, a power rating, and a performance criteria selection.

11. The magnetic flowmeter of claim 10, wherein at least one of the coil resistance, the coil inductance and magnetic flux density is measured by the transmitter.

12. The magnetic flowmeter of claim 10, wherein the processor controls a coil drive duty cycle.

13. The magnetic flowmeter of claim 10, wherein the processor further controls the coil driver based upon at least one of flowtube gain, coil current, electrode noise and electrode voltage zero shift characteristics.

14. The magnetic flowmeter of claim 10, wherein the power rating comprises at least one of flowtube power rating and transmitter power rating.

15. The magnetic flowmeter of claim 10, wherein the performance criteria comprises at least one of fastest response, highest signal-to-noise ratio for a particular excitation frequency, highest-signal-to-noise ratio for a particular accuracy, and power efficiency.

16. A transmitter for use with a magnetic flowtube, the transmitter comprising:

a coil driver for supplying a current to a coil of the magnetic flowtube; and

a processor for determining an operating setpoint based on coil resistance, coil inductance, a power rating, and a performance criteria selection; and

controlling operation of the coil driver based on the operating setpoint.

17. The transmitter of claim 16, wherein the operating setpoint includes an excitation frequency and a coil drive current.

18. The transmitter of claim 17, wherein the operating setpoint further includes a coil drive duty cycle.

19. The transmitter of claim 16, wherein the flowmeter parameters further include at least one of flowtube gain, coil current, electrode noise, signal-to-noise ratio, and electrode voltage zero shift characteristics.

20. The transmitter of claim 16, wherein the power rating comprises at least one of flowtube power rating and transmitter power rating.

21. The transmitter of claim 16, wherein the performance criteria comprises at least one of fastest response, highest signal-to-noise ratio for a particular excitation frequency, highest-signal-to-noise ratio for a particular accuracy, and power efficiency.

22. The transmitter of claim 16, wherein the processor continuously adjusts the operating setpoint.

23. A method of controlling operation of a magnetic flowmeter, the method comprising:

obtaining flowmeter parameters including coil resistance, coil inductance, and a power rating;

obtaining a performance criteria selection;

determining an operating setpoint that includes current and frequency setpoint values based upon the flowmeter parameters and the performance criteria selection; and

controlling field coil excitation of the magnetic flowmeter based on the operating setpoint.

24. The magnetic flowmeter of claim 23, wherein the operating setpoint further includes a coil drive duty cycle setpoint value.

25. The method of claim 23, wherein the flowmeter parameters further include at least one of flowtube gain, coil current, electrode noise, signal-to-noise ratio, and electrode voltage zero shift characteristics.

26. The method of claim 23, wherein the power rating comprises at least one of flowtube power rating and transmitter power rating.

27. The method of claim 23, wherein the performance criteria selection comprises at least one of fastest response, highest signal-to-noise ratio for a particular excitation frequency, highest-signal-to-noise ratio for a particular accuracy, and power efficiency.

28. The method of claim 23 and further comprising:

adjusting the operating setpoint to account for changes in the flowmeter parameters during operation of the magnetic flowmeter.