CIRCUIT ARRANGEMENT FOR REDUCING POWER LOSS IN THE CASE OF AN ACTIVE ELECTRICAL CURRENT OUTPUT OF A FIELD DEVICE

• US 20150002111A1
• Filed: 11/22/2012
• Published: 01/01/2015
• Est. Priority Date: 12/29/2011
• Status: Active Grant

• Current Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Original Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Inventors: Simon, Antoine, Fink, Nikolai, Brudermann, Matthias, Kollmer, Daniel, Koudal, Ole
• Granted Patent: US 9,225,244 B2
• Time in Patent Office: Days
• US Class Current: 323/265
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G05B 19/0423 Input/output
• CPC Class Codes: G05B 2219/21119 Circuit for signal adaption, voltage level shift, filter noise
• CPC Class Codes: G05B 2219/25428 Field device
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

The invention relates to a circuit arrangement for reducing power loss in the case of an active electrical current output of a field device for determining and/or influencing a process variable, wherein the process variable is represented via a selectable electrical current value, comprising an external voltage supply, a voltage regulator and a control loop associated with the voltage regulator, wherein the control loop is so embodied that the voltage regulator, as a function of the presently set electrical current value, so controls the voltage to an external load connected in parallel with the electrical current output that the external load receives essentially only the respectively required voltage.

Claims

1-11. -11. (canceled)

12. A circuit arrangement for reducing power loss in the case of an active electrical current output of a field device for determining and/or influencing a process variable, wherein the process variable is represented via a selectable electrical current value, comprising:

an external voltage supply

a voltage regulator; and

a control loop associated with said voltage regulator, wherein;

said control loop is so embodied that the voltage regulator, as a function of the presently set electrical current value, so controls the voltage to an external load connected in parallel with the electrical current output that the external load receives essentially only the respectively required voltage.

13. The circuit arrangement as claimed in claim 12, wherein:

said control loop controls said voltage regulator in predetermined voltage steps and excess power occurring in given cases is converted into power loss.

14. The circuit arrangement as claimed in claim 12, wherein:

said control loop includes an electrical current controller, especially a transistor, for setting the electrical current value;

an analog-digital converter;

a computation/control unit; and

a reference resistor connected in series with said electrical current controller.

15. The circuit arrangement as claimed in claim 14, wherein:

the analog-digital converter is so arranged that it measures the voltage applied to the reference resistor connected to a reference potential, especially to ground, digitizes the measured voltage and forwards the digital voltage value to said control unit.

16. The circuit arrangement as claimed in claim 12, wherein:

said computation/control unit, based on the measured voltage, the known resistance value and the electrical current value currently to be set, calculates the voltage required by the load and operates the voltage regulator correspondingly.

17. The circuit arrangement as claimed in claim 12, wherein:

said voltage regulator is so embodied that it has a high efficiency.

18. The circuit arrangement as claimed in claim 12, wherein:

said voltage regulator comprises a DC/DC converter.

19. The circuit arrangement as claimed in claim 12, wherein:

said control loop is so embodied that for the case, in which a malfunction occurs, especially an overload at said external load, an interruption of the electrical current supply to said external load or a wiring fault at the signal output of the field device, said voltage regulator turns said electrical current output off.

20. The circuit arrangement as claimed in claim 19, wherein:

said computation/control unit detects the malfunction by noting that said electrical current controller cannot set an electrical current value corresponding to the process variable, even though voltage regulator is delivering the maximum required voltage.

21. The circuit as claimed in claim 12, wherein:

an additional circuit is provided, which supplementally modulates a HART signal onto the signal of said electrical current output.

22. The circuit as claimed in claim 12, wherein:

a circuit for demodulating a HART signal is supplementally connected to said electrical current output, respectively the signal output.