Precision rogowski coil and method for manufacturing same

• US 20060176140A1
• Filed: 02/04/2005
• Published: 08/10/2006
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: James Kesler, Veselin Skendzic
• Inventors: Kesler, James R., Skendzic, Veselin
• Granted Patent: US 7,227,441 B2
• Time in Patent Office: Days
• US Class Current: 336/225
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 21/12 discontinuously variable, e.g. tapped
• CPC Class Codes: H01F 27/40 Structural association with built-in electric component, e.g. fuse
• CPC Class Codes: H01F 5/003 Printed circuit coils
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling

Abstract

An improved Rogowski coil is formed on a toroidal core made of a thermoplastic or other moldable material, the core having a preferably continuous groove or grooves extending around the core. The grooves correspond in size to magnet wire which registers within the grooves, thus controlling the specific location of the wires. The grooving may be helical. A return loop can be provided for return path cancellation, or a reverse winding can be added in a direction opposite to the direction of advancement of the main coil. In using the return loop, a resistive network can be added to improve the cancellation of the return path due to the effect of geometries. In addition, it can compensate for thermal and other variations.

Claims

1. A coil comprising:

a generally toroidally-shaped core;

grooving on the exterior surface of said core; and

a conductive coil extending about said core, said conductive coil being registered in said grooving.

2. The coil of claim 1 further comprising a coating layer overlying and securing the position of said coil.

3. The coil of claim 1 wherein said core is made of a non-magnetic insulating material.

4. The coil of claim 1 wherein said core comprises a moldable polymeric material.

5. The coil of claim 1 wherein said core comprises a thermoplastic material.

6. The coil of claim 1 wherein said conductive coil comprises magnet wire.

7. The coil of claim 1 wherein said grooving comprises a substantially continuous, helical groove.

8. The coil of claim 1 wherein said grooving comprises a discontinuous groove along portions of a helix.

9. The coil of claim 1 wherein said toroidal core is segmented into consecutive arc sections, each arc section having respective grooving substantially across the arc section, wherein a coil section is registered in the grooving of the arc section.

10. The coil of claim 1, said conductive coil extending about said core constituting a main coil, and further comprising a return loop wrapped generally circumferentially about said core.

11. The coil of claim 10 further comprising a resistive network electrically coupled to said return loop and said main coil.

12. The coil of claim 1, said conductive coil extending about said core constituting a main coil, and further comprising a return winding wrapped on top of said main coil in a reverse direction of advancement as said main coil.

23. The coil of claim 1 wherein said grooving comprises:

a substantially radially-oriented components at first locations of the toroid, and

sequential, non-radially oriented components at second locations of the toroid,

said second locations being disposed radially outward of said first locations,

each said radially-oriented component being connected to a corresponding non-radially oriented component,

wherein wire wound in said grooving proceeds radially at said first locations and non-radially at said second locations.

42. The coil according to claim 1 wherein said conductor comprises a conductive material.

43. The coil according to claim 42 wherein said conductor comprises first portions of a conductive material applied to said core after processing to remove second portions of said conductive material.

44. A coil according to claim 1 used to implement a Rogowski coil.

46. A coil according to claim 11 wherein said resistive network compensates for differing radii as between a return path and said coil effective advancement path radius.

47. The coil according to claim 11 wherein said resistive network compensates for thermal effects on the coil.

13. A coil comprising:

a generally toroidally-shaped core comprising a non-magnetic insulating material;

grooving on the exterior surface of said core, at least a portion of said grooving being helical, said grooving being configured to receive wire; and

a wire coil wound in a helical configuration about said core and registered in said grooving.

14. The coil of claim 13 further comprising a coating layer overlying and securing the position of said wire coil.

15. The coil of claim 13 wherein said core comprises a moldable polymeric material.

16. The coil of claim 13 wherein said grooving comprises a substantially continuous groove.

17. The coil of claim 13 wherein said grooving is sized to receive wire of a predetermined gauge, and wherein said wire coil uses wire of said predetermined gauge.

18. The coil of claim 13 wherein said grooving comprises a discontinuous groove along portions of a helix.

19. The coil of claim 13 wherein said toroidal core is segmented into consecutive arc sections, each arc section having respective grooving substantially across the arc section, wherein a coil section is registered in the grooving of the arc section.

20. The coil of claim 13, said wire coil wound about said core constituting a main coil, said main coil having advancing in a first direction and further comprising a return loop wrapped generally circumferentially about said core and advancing in a second direction.

21. The coil of claim 20 further comprising a resistive network electrically coupled to said return loop and said main coil.

22. The coil of claim 13, said wire coil wound about said core constituting a main coil, and further comprising a return winding wrapped on top of said main coil in a reverse direction of advancement as said main coil.

24. The coil of claim 13 wherein said grooving comprises:

a substantially radially-oriented components at first locations of the toroid, and

sequential, non-radially oriented components at second locations of the toroid,

said second locations being disposed radially outward of said first locations,

each said radially-oriented component being connected to a corresponding non-radially oriented component,

wherein wire wound in said grooving proceeds radially at said first locations and non-radially at said second locations.

45. A coil according to claim 13 used to implement a Rogowski coil.

25. A method of making a coil comprising the steps of:

molding a core, including forming grooving on an exterior surface of said core,

winding wire about said core to form a main coil, including using said grooving during said winding to control the location of the wire on said core.

26. The method of claim 25 wherein said molding step comprises molding a generally toroidal core.

27. The method of claim 25 wherein said forming includes forming grooving corresponding to a helical pattern on said core.

28. The method of claim 25:

wherein said molding step comprises molding a toroidal core;

wherein said forming includes forming grooving corresponding to a helical pattern on said core;

wherein said grooving is formed to receive wire of a predetermined gauge; and

wherein said winding step uses wire of said predetermined gauge.

29. The method of claim 25 further comprising applying a coating over said wire wound about said core.

30. The method of claim 29 further including providing a return path cancellation winding.

31. The method of claim 30 wherein said step of providing a return path cancellation winding comprises winding a return loop circumferentially around said core, and further comprising including adding a resistive network to said return loop.

32. The method of claim 25 wherein said step of adding a return path cancellation winding comprises winding a return coil on top of said main coil, said winding of the return coil advancing in a direction opposite to a direction of advancement of the main coil.

33. The method of claim 25 further including providing a resistive network for temperature compensation.

34. The method of claim 25 wherein said molding the core and forming grooving comprise molding said core with said grooving on its exterior.

35. A method of making a coil comprising the steps of:

molding a core, including forming grooving on an exterior surface of said core,

forming a conductive winding about said core to form a main coil, including using said grooving during said winding to control the location of the winding on said core.

36. The method of claim 35 wherein said first-named step produces a molded, grooved core;

and

wherein said step of forming a conductive winding comprises

(a) applying a conductive material on said molded, grooved core, and

(b) selectively removing conductive material from said core.

37. The method of claim 35 wherein said molding step comprises molding a generally toroidal core;

and

wherein said step of forming grooving includes forming grooving corresponding to a helical pattern on said core.

38. The method of claim 35 further including providing a return path cancellation winding.

39. The method of claim 38 comprising including adding a resistive network to said return path cancellation winding.

40. The method of claim 38 wherein said step of providing a return path cancellation winding comprises winding a return loop circumferentially around said core.

41. The method of claim 38 wherein said step of adding a return path cancellation winding comprises winding a return coil on top of said main coil, said winding of the return coil advancing in a direction opposite to a direction of advancement of the main coil.