Vertical winding structures for planar magnetic switched-mode power converters
View Patent ↗A vertical winding structure for planar integrated magnetics used in switched-mode power converters maintains close coupling between the different windings but reduces the eddy current losses, lowers the DC winding resistance and reduces the number of layers of the PCB. Vertical and horizontal windings can be used together without sacrificing these performance advantages and further minimizing the capacitive coupling between the outer-leg windings and the center-leg winding. This winding structure can be used in a wide range of magnetic structures including isolated and non-isolated CDRs, interleaved CDRs, and buck and boost converters.
1. A power converter, comprising:
a multi-layer printed circuit board (PCB) having first, center and second holes formed therethrough, said PCB having a split-primary and secondary windings formed horizontally thereon around said first and second holes;
a magnetic core having a base below said PCB, first, center and second legs on said base and extending through said respective holes in said PCB so that said split-primary and secondary windings are wound around said first and second legs, and a plate above said PCB on said first and second legs; and
a vertical inductor winding around said center leg.
2. The power converter as recited in claim 1 wherein said vertical inductor winding is approximately orthogonal to said base and said plate and approximately parallel to said center leg.
3. The power converter as recited in claim 1 wherein said vertical inductor winding makes a single physical and magnetic turn.
4. The power converter as recited in claim 1 wherein said vertical inductor winding comprises a winding termination on said PCB.
5. The power converter as recited in claim 1 wherein said vertical inductor winding is thicker than said split-primary and secondary windings.
6. The power converter as recited in claim 1 wherein said vertical inductor winding is implemented by winding a piece of copper foil around said center leg.
7. The power converter as recited in claim 1 wherein said vertical inductor winding and said secondary windings make a single physical and magnetic turn, and said primary windings make two physical and magnetic turns.
8. The power converter as recited in claim 1 wherein an air gap is formed between said center leg and said plate.
9. The power converter as recited in claim 1 wherein said center hole is larger than said first and second holes.
10. The power converter as recited in claim 1 wherein said split-primary and secondary windings are arranged alternately on said PCB around said first and second holes.
11. A power converter, comprising:
a matrix integrated magnetic (MIM) core, including:
a base,
first, second, third and fourth legs disposed at opposite corners of said base to define windows therebetween,
a center leg disposed at a center of said base and extending in a plus shape into said windows and separated from said first, second, third and fourth legs, and
a plate opposite said base; and
a vertical winding around at least one of said first, second, third, fourth and center legs.
12. The power converter as recited in claim 11 further comprising horizontal windings around said first, second, third and fourth legs.
13. The power converter as recited in claim 11 further comprising horizontal windings formed in a multi-layer printed circuit board (PCB) around said first, second, third and fourth legs.
14. The power converter as recited in claim 11 further comprising split-primary and secondary windings formed as horizontal windings around said first, second, third and fourth legs.
15. The power converter as recited in claim 11 wherein said vertical winding is around said center leg.
16. The power converter as recited in claim 11 wherein said vertical winding is an inductor winding.
17. The power converter as recited in claim 11 wherein said vertical winding is implemented by winding a piece of copper foil around said center leg.
18. The power converter as recited in claim 11 wherein an air gap is formed between said center leg and said plate.
19. The power converter as recited in claim 11 wherein said plate is disposed on said first, second, third and fourth legs.
20. The power converter as recited in claim 11 wherein said base is a rectangular base.