Continuously adaptive digital coil driver for magnetic flowmeter

Patent metadata

Field	Value
Publication number	US-11204267-B2
Application number	US-201916587615-A
Country	US
Kind code	B2
Filing date	Sep 30, 2019
Priority date	Sep 5, 2019
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

A magnetic flowmeter for measuring a fluid flow includes flow tube assembly receiving the flow having a coil with first and second coil wires for receiving a coil current to produce a magnetic field in the fluid. This generates an EMF in the fluid representative of the flow. An EMF sensor is arranged to sense the EMF and generate an output related to the flow rate. Current supply circuitry provides the coil current to the first and second wires of the coil in response to a command signal. A digital control circuit provides the command signal to the current supply circuitry as a function of a control algorithm. In one aspect, the control algorithm is adapted to changes in electrical parameters of the coil. A method of implementing the magnetic flowmeter is also provided.

First claim

What is claimed is:

1. A magnetic flowmeter for measuring a fluid flow, comprising:
a flow tube assembly receiving the flow having a coil with first and second coil wires for receiving a coil current producing a magnetic field generating an EMF in the fluid representative of the flow;
an EMF sensor arranged to sense the EMF and generate an output indicating the flow;
current supply circuitry configured to provide the coil current to the first and second wires of the coil in response to a command input; and
digital control circuit which provides the command input to the current supply circuitry as a function of a control algorithm,
wherein the command input comprises a pulse wave modulated (PWM) signal that controls a direction the coil current travels through the coil.

2. The magnetic flowmeter of claim 1 wherein the current supply circuitry includes a current source and at least one switch for selectively coupling the current source to the coil.

3. The magnetic flowmeter of claim 2 wherein the PWM signal is applied to the at least one switch.

4. The magnetic flowmeter of claim 1 , including a low pass filter which connects the current supply circuitry to the coil to provide a DC coil current to the coil.

5. The magnetic flowmeter of claim 1 wherein the control algorithm is configured to control the command input as a function of a current profile.

6. The magnetic flowmeter of claim 5 wherein the current profile includes at least one of amplitude, frequency, waveform and overshoot.

7. The magnetic flowmeter of claim 1 wherein the digital control circuitry includes an impedance identification algorithm configured to determine an impedance of the coil and the command input is a function of the determined impedance.

8. The magnetic flowmeter of claim 7 wherein the impedance identification algorithm receives a current feedback signal related to current through the coil for use in determining impedance of the coil.

9. The magnetic flowmeter of claim 1 wherein the current supply circuitry includes four switches configured to control the current through the coil.

10. The magnetic flowmeter of claim 9 wherein the command input comprises four signals individually applied to each of the four switches.

11. The magnetic flowmeter of claim 9 wherein the command input comprises two signals applied to two pairs of the four switches.

12. The magnetic flowmeter of claim 1 wherein the control algorithm configured to generate the command input as a function of a sensed current flowing through the coil and the digital control circuit includes:
an impedance identification algorithm configured to identify impedance of the coil as a function of the sensed current and the command input and responsively control parameters of the control algorithm.

13. The magnetic flowmeter of claim 1 wherein parameters of the control algorithm are adapted to changes in electrical parameters of the coil.

14. A method for measuring flow of a process fluid using a magnetic flowmeter, comprising:
receiving a flow of process fluid through a flow tube assembly having a coil with first and second wires for receiving a coil current and responsively producing a magnetic field and generating EMF in the fluid representative of a flow rate;
sensing the EMF with a sensor and generating an output indicating flow rate;
providing the coil current to the first and second wires of the coil using current supply circuitry which is responsive to a command input;
generating the command input comprising a pulse wave modulated (PWM) signal; and
controlling a direction the coil current travels through the coil comprising applying the command input to the current supply circuitry.

15. The method of claim 14 wherein the control algorithm is configured to control the command input as a function of a current profile.

16. The method of claim 15 wherein the current profile includes at least one of amplitude, frequency, waveform and overshoot.

17. The method of claim 14 wherein the digital control circuitry includes an impedance identification algorithm for determining an impedance of the coil and the command input is a function of the determined impedance.

18. The method of claim 17 wherein the impedance identification algorithm receives a current feedback signal related to current through the coil for use in determining impedance of the coil.

19. A magnetic flowmeter for measuring a fluid flow, comprising:
a flow tube assembly receiving the flow having a coil with first and second coil wires for receiving a coil current producing a magnetic field generating an EMF in the fluid representative of the flow;
an EMF sensor arranged to sense the EMF and generate an output indicating the flow;
current supply circuitry configured to provide the coil current to the first and second wires of the coil in response to a command input; and
digital control circuit which provides the command input to the current supply circuitry as a function of a control algorithm,
wherein:
the current supply circuitry includes four switches configured to control the current through the coil;
the command input comprises a pulse wave modulated (PWM) signal that is applied to each of the four switches; and
a direction the coil current travels through the coil is controlled by the command input.

Assignees

• Micro Motion Inc

Inventors

• Ameri Masoud

Classifications

• G01F1/586 Primary

  constructions of coils, magnetic circuits, accessories therefor (G01F1/582 takes precedence; magnet; inductances; transformers; selection of materials for their magnetic properties per se H01F) · CPC title

• G01F15/066

  involving magnetic transmission devices · CPC title

• G01F1/60 Primary

  Circuits therefor · CPC title