Current Shunt

• US 20130328547A1
• Filed: 12/11/2012
• Published: 12/12/2013
• Est. Priority Date: 12/23/2011
• Status: Active Grant

• Current Assignee: GE Energy Power Conversion Technology Limited (General Electric Company), Sensata Technologies Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Sendyne Corp. (Sensata Technologies Holding Plc)
• Inventors: Marten, Victor
• Granted Patent: US 9,217,759 B2
• Time in Patent Office: Days
• US Class Current: 324/126
• CPC Class Codes: G01R 1/20 Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
• CPC Class Codes: G01R 1/203 Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G11B 2005/001 Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure
• CPC Class Codes: G11B 2005/0016 of magnetoresistive transducers
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/455 Arrangements for functional testing of heads; Measuring arrangements for heads

Abstract

Methods and circuits for reduction of errors in a current shunt are disclosed, for example sensing lines for Kelvin sensing in which the sensing lines are of identical material to the high-resistance portions of the shunt, and welded thereto. This allows application of a current shunt with lower output voltage and thus lower power losses than the contemporary art implementations, while maintaining high accuracy with regard to temperature changes.

Claims

1. A method for measurement of a current, the method comprising the steps of:

passing the current through a shunt, the passage of the first current through the shunt defining a flow path from a first point to a second point to a third point to a fourth point;

the shunt composed between the first point and the second point of a first material;

the shunt composed between the third point and the fourth point of a third material;

communicating a potential from the second point through an electrical conductor to a fifth point, the conductor composed between the second point and the fifth point of a fourth material;

communicating a potential from the third point through an electrical conductor to a sixth point, the conductor composed between the sixth point and the third point of a fifth material;

the first and fourth materials being of respective identical composition and being electrically and mechanically bonded, said bond substantially free of anything other than said respective identical composition;

the third and fifth materials being of respective identical composition and being electrically and mechanically bonded, said bond substantially free of anything other than said respective identical composition;

the first and third materials being electrically conductive;

wherein the respective identical composition of the third and fifth materials and the respective identical composition of the first and fourth materials are identical;

and wherein the shunt between the second point and the third point is composed of a second material identical to the first and third materials;

the method further comprising providing a conductor from the fifth point to a seventh point, said conductor composed of a sixth material non-identical to the fourth material, and providing a conductor from the sixth point to an eighth point, said conductor composed of a seventh material non-identical to the fifth material,

the fifth and sixth points closely juxtaposed and the fifth and sixth points thermally isolated, whereby the fifth and sixth points tend to be nearby to each other in temperature;

the method further comprising the step of communicating a potential from the fifth point to the seventh point, and communicating a potential from the sixth point to the eighth point;

the method further comprising measuring voltage between the seventh point and the eighth point at a voltage measurement apparatus.

2. The method of claim 1 wherein the bonds are welded.

3. The method of claim 1 further comprising the steps of:

providing a conductor from a ninth point, the ninth point nearby to the second point, to a tenth point;

the conductor composed between the ninth point and the tenth point of an eighth material;

providing a conductor from an eleventh point to a twelfth point, the twelfth point nearby to the third point;

the conductor composed between the eleventh point and the twelfth point of a ninth material;

the eighth material and the first material being non-identical;

the ninth material and the third material being non-identical;

measuring a potential at the tenth point, said potential indicative of temperature at the ninth point; and

measuring a potential at the eleventh point, said potential indicative of temperature at the twelfth point.

4. The method of claim 3 wherein the eighth and ninth materials are identical to each other and wherein the first and second materials are identical to each other.

5. The method of claim 3 wherein determination of the first current is corrected for temperature changes within the shunt by means of the temperatures indicated at the ninth point and at the twelfth point.

6. The method of claim 1 further comprising the steps of:

providing a conductor from a thirteenth point, the thirteenth point midway between the second point and the third point, to a fourteenth point;

the conductor composed between the thirteenth point and the fourteenth point of a tenth material;

the seventh material and the material between the second point and the third point being non-identical;

measuring a potential at the fourteenth point, said potential indicative of temperature at the thirteenth point.

7. The method of claim 6 wherein determination of the first current is corrected for temperature changes within the shunt by means of the temperature indicated at the thirteenth point.

8. Apparatus for current measurement, the apparatus comprising a shunt, the shunt defining a current flow path from a first point to a second point to a third point to a fourth point;

the shunt composed between the first point and the second point of a first material;

the shunt composed between the third point and the fourth point of a third material;

the apparatus further comprising an electrical conductor from the second point to a fifth point, the electrical conductor composed between the second point and the fifth point of a fourth material;

the apparatus further comprising an electrical conductor from a sixth point to the third point, the electrical conductor composed between the sixth point and the third point of a fifth material;

the first and fourth materials being of respective identical composition and being electrically and mechanically bonded, said bond substantially free of anything other than said respective identical composition;

the third and fifth materials being of respective identical composition and being electrically and mechanically bonded, said bond substantially free of anything other than said respective identical composition;

the first and third materials being electrically conductive;

wherein the respective identical composition of the first and fourth materials and the respective identical composition of the third and fifth materials are identical;

wherein the shunt between the second point and the third point is composed of a second material identical to the first and third materials;

the apparatus further comprising;

a conductor from the fifth point to a seventh point, said conductor composed of a sixth material non-identical to the fourth material,

a conductor from the sixth point to an eighth point, said conductor composed of a seventh material non-identical to the fifth material,

the fifth and sixth points closely juxtaposed and the fifth and sixth points thermally isolated, whereby the fifth and sixth points tend to be nearby to each other in temperature;

the seventh point and the eighth point disposed for connection to a voltage measurement apparatus.

9. The apparatus of claim 8 wherein the bonds are welded.

10. The apparatus of claim 8 further comprising:

an electrical conductor from a ninth point, the ninth point nearby to the second point, to a tenth point, the conductor composed between the ninth point and the tenth point of an eighth material, the eighth material and the first material being non-identical;

an electrical conductor from an eleventh point to a twelfth point, the twelfth point nearby to the third point, the conductor composed between the eleventh point and the twelfth point of a ninth material, the ninth material and the third material being non-identical;

the tenth and eleventh points disposed for connection to voltage measurement apparatus.

11. The apparatus of claim 10 further comprising:

voltage measurement apparatus connected to the tenth and eleventh points, and computational means responsive to potentials measured at the tenth point and at the eleventh point for correcting determination of current through the shunt by means of the temperatures indicated at the ninth point and at the twelfth point by the potentials measured thereat.

12. The apparatus of claim 10 wherein the eighth and ninth materials are identical to each other and wherein the first and third materials are identical to each other.

13. The apparatus of claim 10 further comprising:

an electrical conductor from a thirteenth point, the thirteenth point midway between second point and the third point, to a fourteenth point, the conductor composed between the thirteenth point and the fourteenth point of a tenth material, the tenth material and the material between the second point and the third point being non-identical,

the fourteenth point disposed for connection to voltage measurement apparatus.

14. The apparatus of claim 13 further comprising:

voltage measurement apparatus connected to the fourteenth point, and

computational means responsive to potentials measured at the fourteenth point for correcting determination of current through the shunt by means of the temperature indicated at the thirteenth point by the potential measured thereat.

15. The apparatus of claim 8 wherein the current flow path from the first point to the second point to the third point to the fourth point is substantially along a straight line.

16. The apparatus of claim 8 further comprising a voltage measurement apparatus connected with the seventh point and the eighth point.

17. A method for measurement of a current, the method comprising the steps of:

passing the current through a shunt, the passage of the first current through the shunt defining a flow path from a first point to a second point to a third point to a fourth point;

the shunt composed between the first point and the second point of a first material;

the shunt composed between the third point and the fourth point of a third material;

communicating a potential from the second point through an electrical conductor to a fifth point, the conductor composed between the second point and the fifth point of a fourth material;

communicating a potential from the third point through an electrical conductor to a sixth point, the conductor composed between the sixth point and the third point of a fifth material;

the first and fourth materials being of non-identical composition and being electrically and mechanically bonded;

the third and fifth materials being of non-identical composition and being electrically and mechanically bonded;

the first and third materials being electrically conductive;

wherein the shunt between the second point and the third point is composed in part of a second material non-identical to the first and third materials, the second material being electrically conductive but less conductive than said first and third materials;

the fifth and sixth points closely juxtaposed and the fifth and sixth points thermally isolated, whereby the fifth and sixth points tend to be nearby to each other in temperature;

the method further comprising the step of communicating a potential from the fifth point to a seventh point, and communicating a potential from the sixth point to an eighth point;

the method further comprising measuring voltage between the seventh point and the eighth point.

18. The method of claim 17 wherein the bonds are welded.

19. The method of claim 17 wherein the composition of the fifth material and the composition of the fourth material are identical.

20. The method of claim 19 wherein the composition of the second material is identical to that of the fourth and fifth materials.

21. The method of claim 17 wherein the material between the fifth and seventh points is of differing composition than the material between the fifth and second points, and wherein the material between the sixth and eighth points is of differing composition than the material between the sixth and third points.

22. Apparatus for current measurement, the apparatus comprising a shunt, the shunt defining a current flow path from a first point to a second point to a third point to a fourth point;

the shunt composed between the first point and the second point of a first material;

the shunt composed between the third point and the fourth point of a third material;

the apparatus further comprising an electrical conductor from the second point to a fifth point, the electrical conductor composed between the second point and the fifth point of a fourth material;

the apparatus further comprising an electrical conductor from a sixth point to the third point, the electrical conductor composed between the sixth point and the third point of a fifth material;

the first and fourth materials being of non-identical composition and being electrically and mechanically bonded;

the third and fifth materials being of non-identical composition and being electrically and mechanically bonded;

the first and third materials being electrically conductive;

wherein the shunt between the second point and the third point is composed in part of a second material non-identical to the first and third materials, the second material being electrically conductive but less conductive than said first and third materials;

a conductor from the fifth point to a seventh point, said conductor composed of a sixth material non-identical to the fourth material,

a conductor from the sixth point to an eighth point, said conductor composed of a seventh material non-identical to the fifth material,

the fifth and sixth points closely juxtaposed and the fifth and sixth points thermally isolated, whereby the fifth and sixth points tend to be nearby to each other in temperature;

the seventh point and the eighth point disposed for connection to a voltage measurement apparatus.

23. The apparatus of claim 22 wherein the bonds are welded.

24. The apparatus of claim 22 wherein the composition of the fourth material and the composition of the fifth material are identical.

25. The apparatus of claim 24 wherein the composition of the second material is identical to that of the fourth and fifth materials.

26. The apparatus of claim 22 further comprising a current measurement apparatus connected to the seventh point and to the eighth point.

27. The apparatus of claim 22 wherein the current flow path from the first point to the second point to the third point to the fourth point is substantially along a straight line.

28. The apparatus of claim 22 wherein the material between the fifth and seventh points is of differing composition than the material between the fifth and second points, and wherein the material between the sixth and eighth points is of differing composition than the material between the sixth and third points.