Method for controlling coil current of a magneto inductive, flow measuring device

Patent metadata

Field	Value
Publication number	US-9893611-B2
Application number	US-201314410680-A
Country	US
Kind code	B2
Filing date	Jun 4, 2013
Priority date	Jun 28, 2012
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

A method for controlling coil current of a magneto inductive, flow measuring device with a first value representing an overvoltage U O and a second value representing a holding voltage U H , wherein the first value is greater than the second value, characterized by steps as follows: setting a first switching point I S for the electrical current level, up to which a coil should be supplied with the overvoltage U O ; applying an overvoltage U O until the electrical current level rises to the switching point IS set for the electrical current level; switching from the overvoltage U O to the holding voltage U H , in order to hold the electrical current level at a constant electrical current end value I H . Also intended is a magneto inductive, flow measuring device.

First claim

The invention claimed is:

1. A method for controlling coil current of a magneto inductive, flow measuring device with a first value representing an overvoltage UO and a second value representing a holding voltage UH, wherein the first value is greater than the second value, comprising the steps of:
setting a first switching point IS for the electrical current level, up to which a coil should be supplied with the overvoltage UO;
applying an overvoltage UQ until the electrical current level rises to the switching point Is set for the electrical current level;
switching from the overvoltage UQ to the holding voltage UH, in order to hold the electrical current level at a constant electrical current end value IH; and
after said switching, an evaluation of a current electrical current level I occurs, along with an adjusting of the switching point L of the electrical current level is performed by a comparator.

2. The method as claimed in claim 1 , wherein:
a comparison of the current electrical current level I R with said switching point I S of the electrical current level is performed by a comparator.

3. The method as claimed in claim 2 , wherein:
said switching from the overvoltage U O to the holding voltage U H is initiated by said comparator; and
said switching of said comparator is evaluated, in order to prevent a switching back to the overvoltage U O .

4. The method as claimed in claim 3 , wherein:
said switching back of the holding voltage U H to the overvoltage U O is prevented by a flip-flop circuit.

5. The method as claimed in claim 1 , wherein:
a comparison of an input signal E of an electrical current equivalent voltage with a desired value for an electrical current level equivalent voltage S of the switching point I S occurs time independently before said switching.

6. The method as claimed in claim 1 , wherein:
said setting of the first switching point I S occurs according to the following:
i) ascertaining a value, which represents a current electrical current level I R , after said switching;
ii) comparing the current electrical current level I R with a preset desired end value for the electrical current end value I End , which occurs in the case of continued holding voltage U H ; and
iii) changing the switching point I S , in the case of a deviation of the current electrical current level I R from the electrical current end value I End .

7. The method as claimed in claim 1 , wherein:
the first value representing the overvoltage U O is greater than twice as large as the second value representing the holding voltage U H .

8. The use of the method as claimed in claim 1 , for controlling the coil current of a magneto inductive, flow measuring device in two conductor technology.

9. A magneto inductive, flow measuring device, comprising:
a coil arrangement; and
a circuit for controlling a coil current, according to a method which comprises a method for controlling coil current of a magneto inductive, flow measuring device with a first value representing an overvoltage U O and a second value representing a holding voltage U H , wherein the first value is greater than the second value, comprising the steps of: setting a first switching point IS for the electrical current level, up to which a coil should be supplied with the overvoltage U O ; applying an overvoltage U O until the electrical current level rises to the switching point I S set for the electrical current level; and switching from the overvoltage U O to the holding voltage U H , in order to hold the electrical current level at a constant electrical current end value I H , which circuit is designed to supply the coil arrangement with an overvoltage U O and a holding voltage U H , wherein:
said circuit has a comparator for comparing the current electrical current level I R with a switching point I s of the electrical current level;
said circuit is adapted to switch from the overvoltage U O to the holding voltage U H upon reaching the switching point I S of the electrical current level; and
after switching, an evaluation of a current electrical current level I occurs, along with an adjusting of the switching point I S of the electrical current level is performed by a comparator.

10. The magneto inductive flow measuring device as claimed in claim 9 , wherein:
said magneto inductive flow measuring device is embodied preferably as a two conductor field device.

11. The magneto inductive flow measuring device as claimed in claim 10 , wherein:
said circuit additionally contains a flip-flop circuit for preventing switching back from the holding voltage U H to the overvoltage U O .

Assignees

• Endress & Hauser Flowtec Ag

Inventors

• Rufenacht Markus
• Spahlinger Andre
• Kung Thomas

Classifications

• G01R19/165

  Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values · CPC title

• H02M3/04 Primary

  by static converters · CPC title

• G01F1/60 Primary

  Circuits therefor · CPC title