Minimal-length windings for reduction of copper power losses in magnetic elements

• US 20090302986A1
• Filed: 06/10/2008
• Published: 12/10/2009
• Est. Priority Date: 06/10/2008
• Status: Abandoned Application

• Current Assignee: Tiberiu A. Bedea
• Original Assignee: Tiberiu A. Bedea
• Inventors: Bedea, Tiberiu A.
• Application Number:
  US12/155,781
• Publication Number:
  US 20090302986A1
• Time in Patent Office: Days
• US Class Current: 336/55
• CPC Class Codes: H01F 27/006 with special arrangement or spacing of turns of the winding(s), e.g. to produce desired self-resonance
• CPC Class Codes: H01F 27/2847 Sheets; Strips H01F27/2866 takes precedence
• CPC Class Codes: H01F 27/34 Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• CPC Class Codes: H01F 3/08 made from powder powder coatings on sheets H01F3/02; on strips or ribbons H01F3/04; on wires H01F3/06

Abstract

The present invention discloses means for reducing copper power losses in windings of magnetic elements by minimizing their length. This is achieved by winding a continuous copper foil of a specific geometrical design at least one turn over a ferromagnetic core with the surface of the foil parallel to the surface of the core The transformer may have high or low turn ratios, may also use winding coil formers to achieve proper creepage and clearance and may use a compressible, thermally conductive pad for facilitating heat dissipation.

Claims

1. A method to minimize copper losses in magnetics of at least one winding turn, the method comprising the minimization of the length of the said at least one turn by winding a continuous copper foil of a specific geometrical design at least one turn over a ferromagnetic core with the surface of the foil parallel to the surface of the core, so as to achieve a winding turn-length quasi-equal to the length of the core cross-section perimeter, effectively surrounding the entire cross-sectional area of the ferromagnetic core.

2. The method of claim 1, wherein the ferromagnetic core is a ferrite.

3. The method of claim 1, wherein said at least one winding turn is made of copper foil.

4. The method of claim 1, wherein said at least one winding turn is made of flexible PCB.

5. The method of claim 1, wherein said at least one winding turn features a central tap.

6. The method of claim 1, wherein said at least one winding turn is made of multiple layers.

7. A magnetics winding comprising at least one winding turn that, for a given magnetics core volume, features a minimized length obtained by winding a continuous copper foil of a specific geometrical design at least one turn around a ferromagnetic core to achieve a winding turn-length quasi-equal to the length of the core cross-section perimeter, thus effectively surrounding the entire cross-sectional area of the ferromagnetic core.

8. The winding of claim 7, wherein the ferromagnetic core is a ferrite.

9. The winding of claim 7, wherein said at least one winding turn is made of copper foil.

10. The winding of claim 7, wherein said at least one winding turn is made of flexible PCB.

11. The winding of claim 7, wherein said at least one winding turn features a central tap.

12. The winding of claim 7, wherein said at least one winding turn is made of multiple layers.

13. A transformer comprising a secondary winding with at least one winding turn that features reduced copper losses by minimizing the said at least one turn length by winding a continuous copper foil of a specific geometrical design at least one turn over a ferromagnetic core with the surface of the foil parallel to the surface of the core, so as to achieve a winding turn-length quasi-equal to the length of the core cross-section perimeter, thus effectively surrounding the entire cross-sectional area of the ferromagnetic core.

14. The transformer of claim 13, wherein a low turn ratio is used.

15. The transformer of claim 13, wherein a high turn ratio is used.

16. The transformer of claim 13, wherein proper creepage and clearance are provided by using secondary winding coil formers.

17. The transformer of claim 13, wherein proper creepage and clearance are provided by using primary winding coil formers.

18. The transformer of claim 17, wherein the primary winding coil former supports Litz wire windings.

19. The transformer of claim 13, wherein said transformer core is placed in contact with a thermally conductive U-shaped top and a thermally conductive base plate via a compressible conductive pad featuring holes for facilitating its attachment to an external heat-sink.