Ripple-current reduction for transformers

• US 20050073863A1
• Filed: 05/14/2004
• Published: 04/07/2005
• Est. Priority Date: 10/01/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: de Rooij, Michael Andrew, Schutten, Michael Joseph, Steigerwald, Robert Louis
• Granted Patent: US 7,142,440 B2
• Time in Patent Office: Days
• US Class Current: 363/39
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 1/143 using compensating arrangements for reducing noise from the supply in transmission systems H04B15/005
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

Abstract

A ripple current reduction circuit is provided that reduces the ripple current of a transformer by providing a substantially opposite or inverse ripple of an auxiliary current that can be combined with the ripple current of the transformer for cancellation or reduction of the ripple current.

Claims

1. A ripple current reduction circuit connectable to a transformer having primary and secondary windings, a leakage inductance and a first ripple current, the reduction circuit comprising:

a first capacitor across which an output voltage is provided; and

an auxiliary circuit operably connected to the transformer and said first capacitor, wherein said auxiliary circuit has an auxiliary current having a second ripple current, wherein said second ripple current is substantially an inverse of the first ripple current, and wherein said auxiliary circuit combines said auxiliary current with the first ripple current to create a substantially high frequency ripple free current.

2. The reduction circuit of claim 1, wherein said auxiliary circuit comprises:

an auxiliary transformer having an auxiliary primary winding and an auxiliary secondary winding, said auxiliary transformer being operably coupled to the leakage inductance of the transformer; and

a second capacitor in series with said auxiliary secondary winding.

3. The reduction circuit of claim 2, wherein said auxiliary circuit further comprises an auxiliary inductor and a damping resistor in series with said second capacitor and said auxiliary secondary winding.

4. The reduction circuit of claim 1, wherein said auxiliary circuit comprises:

a first auxiliary winding connected to the primary winding of the transformer;

an auxiliary transformer having an auxiliary primary winding and an auxiliary secondary winding, said auxiliary transformer being operably coupled to the leakage inductance of the transformer; and

a second capacitor in series with said auxiliary secondary winding.

5. The reduction circuit of claim 4, wherein said auxiliary circuit further comprises an auxiliary inductor and a damping resistor in series with said second capacitor and said auxiliary secondary winding.

6. The reduction circuit of claim 1, wherein said auxiliary circuit comprises:

a first auxiliary winding connected to the secondary winding of the transformer; and

a second auxiliary winding connected to the primary winding of the transformer.

7. The reduction circuit of claim 6, wherein said auxiliary circuit further comprises:

a second capacitor in series with said first and second auxiliary windings;

an auxiliary inductor in series with said second capacitor and said first and second auxiliary windings; and

a damping resistor in series with said second capacitor and said first and second auxiliary windings.

8. The reduction circuit of claim 6, wherein said auxiliary circuit further comprises an auxiliary inductor connected to a portion of a core of the transformer that has minimal flux.

9. The reduction circuit of claim 6, wherein said auxiliary circuit further comprises a second capacitor that is integrally formed with said first and second auxiliary windings.

10. The circuit of claim 9, wherein said auxiliary circuit further comprises a damping resistor that is integrally formed with said second capacitor and said first and second auxiliary windings.

11. The circuit of claim 10, wherein said damping resistor is integrally formed with said second capacitor and said first and second auxiliary windings through use of a lossy dielectric material.

12. The circuit of claim 1, wherein said auxiliary circuit comprises a first auxiliary winding wound between the primary and secondary windings of the transformer.

13. The reduction circuit of claim 12, wherein said first auxiliary winding is separated from either or both of the primary and secondary windings of the transformer.

14. The reduction circuit of claim 12, wherein said auxiliary circuit further comprises:

a second capacitor in series with said first auxiliary winding;

an auxiliary inductor in series with said second capacitor and said first auxiliary winding; and

a damping resistor in series with said second capacitor and said first auxiliary winding.

15. The reduction circuit of claim 12, wherein said auxiliary circuit further comprises a second capacitor that is integrally formed with said first auxiliary winding.

16. The reduction circuit of claim 15, wherein said auxiliary circuit further comprises a damping resistor that is integrally formed with said second capacitor and said first auxiliary winding.

17. The reduction circuit of claim 16, wherein said damping resistor is integrally formed with said second capacitor and said first auxiliary winding through use of a lossy dielectric material.

18. A ripple current reduction transformer circuit comprising:

a main transformer having primary and secondary windings, a leakage inductance and a first ripple current;

a first capacitor across which an output voltage is provided; and

an auxiliary circuit operably connected to said main transformer and said first capacitor, wherein said auxiliary circuit has an auxiliary current having a second ripple current, wherein said second ripple current is substantially an inverse of said first ripple current, and wherein said auxiliary circuit combines said auxiliary current with said first ripple current.

19. The reduction transformer circuit of claim 18, wherein said auxiliary circuit comprises:

an auxiliary transformer having an auxiliary primary winding and an auxiliary secondary winding, said auxiliary transformer being operably coupled to said leakage inductance of said main transformer; and

a second capacitor in series with said auxiliary secondary winding.

20. The reduction transformer circuit of claim 19, wherein said auxiliary circuit further comprises an auxiliary inductor and a damping resistor in series with said second capacitor and said auxiliary secondary winding.

21. The reduction transformer circuit of claim 18, wherein said auxiliary circuit comprises:

a first auxiliary winding connected to said primary winding of said main transformer;

an auxiliary transformer having an auxiliary primary winding and an auxiliary secondary winding, said auxiliary transformer being operably coupled to said leakage inductance of said main transformer; and

a second capacitor in series with said auxiliary secondary winding.

22. The reduction transformer circuit of claim 21, wherein said auxiliary circuit further comprises an auxiliary inductor and a damping resistor in series with said second capacitor and said auxiliary secondary winding.

23. The reduction transformer circuit of claim 18, wherein said auxiliary circuit comprises:

a first auxiliary winding connected to said secondary winding of said main transformer; and

a second auxiliary winding connected to said primary winding of said main transformer.

24. The reduction transformer circuit of claim 23, wherein said auxiliary circuit further comprises:

a second capacitor in series with said first and second auxiliary windings;

an auxiliary inductor in series with said second capacitor and said first and second auxiliary windings; and

a damping resistor in series with said second capacitor and said first and second auxiliary windings.

25. The reduction transformer circuit of claim 23, wherein said auxiliary circuit further comprises an auxiliary inductor connected to a portion of a core of said main transformer that has minimal flux.

26. The reduction transformer circuit of claim 23, wherein said auxiliary circuit further comprises a second capacitor that is integrally formed with said first and second auxiliary windings.

27. The reduction transformer circuit of claim 26, wherein said auxiliary circuit further comprises a damping resistor that is integrally formed with said second capacitor and said first and second auxiliary windings.

28. The reduction transformer circuit of claim 27, wherein said damping resistor is integrally formed with said second capacitor and said first and second auxiliary windings through use of a lossy dielectric material.

29. The reduction transformer circuit of claim 18, wherein said auxiliary circuit comprises a first auxiliary winding wound between said primary and secondary windings of said main transformer.

30. The reduction transformer circuit of claim 29, wherein said first auxiliary winding is separated from either or both of said primary and secondary windings of said main transformer.

31. The reduction transformer circuit of claim 29, wherein said auxiliary circuit further comprises:

a second capacitor in series with said first auxiliary winding;

an auxiliary inductor in series with said second capacitor and said first auxiliary winding; and

a damping resistor in series with said second capacitor and said first auxiliary winding.

32. The reduction transformer circuit of claim 29, wherein said auxiliary circuit further comprises a second capacitor that is integrally formed with said first auxiliary winding.

33. The reduction transformer circuit of claim 32, wherein said auxiliary circuit further comprises a damping resistor that is integrally formed with said second capacitor and said first auxiliary winding.

34. The reduction transformer circuit of claim 33, wherein said damping resistor is integrally formed with said second capacitor and said first auxiliary winding through use of a lossy dielectric material.

35. A method of reducing a first ripple current of a transformer passing into a filter capacitor comprising:

providing an auxiliary current having a second ripple current that is substantially an inverse of the first ripple current; and

combining said auxiliary current with the first ripple current.

36. The method of claim 35, wherein said auxiliary current is provided by an auxiliary circuit operably connected to the transformer and comprising an auxiliary transformer, a second capacitor, an auxiliary inductor and a damping resistor, wherein said auxiliary transformer is operably coupled to a leakage inductance of the transformer.

37. The method of claim 35, wherein said auxiliary current is provided by an auxiliary circuit operably connected to the transformer and comprising a first auxiliary winding, an auxiliary transformer, a second capacitor, an auxiliary inductor and a damping resistor, wherein said first auxiliary winding is tightly coupled magnetically to a primary winding of the transformer, and wherein said auxiliary transformer is operably coupled to a leakage inductance of the transformer.

38. The method of claim 35, wherein said auxiliary current is provided by an auxiliary circuit operably connected to the transformer and comprising a first auxiliary winding, a second auxiliary winding, a second capacitor, an auxiliary inductor, and a damping resistor, wherein said first auxiliary winding is tightly coupled magnetically to a secondary winding of the transformer, and wherein said second auxiliary winding is tightly coupled magnetically to a primary winding of the transformer.

39. The method of claim 35, wherein said auxiliary current is provided by an auxiliary circuit operably connected to the transformer and comprising a first auxiliary winding, a second capacitor, an auxiliary inductor, and a damping resistor, wherein said first auxiliary winding is wound between primary and secondary windings of the transformer.