Fabrication method and structure for embedded core transformers
First Claim
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1. An embedded core transformer comprising:
- a base enclosure having a base wall and a perimeter wall forming a cavity with an open top;
a magnetic core disposed inside the cavity comprising a volume of magnetic material formed as a closed magnetic circuit having a plurality of magnetic circuit legs;
a plurality of conductive winding elements disposed inside the cavity, each comprising a conductive sheet metal element formed to partially encircle one of the magnetic circuit legs, wherein each conductive sheet metal element includes three legs with two of the three legs formed to extend above the perimeter wall through the open top;
means, sized to attach to the perimeter wall for closing the open top, for electrically interconnecting with each winding element by connecting with the two legs that extend above the perimeter wall and further configured with first conductive traces for forming a primary winding circuit that includes a first portion of the winding elements and second conductive traces for forming a secondary winding circuit that includes a remaining portion of the winding elements; and
,wherein the primary winding circuit is inductively coupled with the secondary winding circuit through the magnetic core.
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Abstract
An embedded core electrical transformer (120) for DC to DC current conversion at a switching frequency of 1 MHz has reduced volume and weight with increased power density. The electrical transformer (120) utilizes a plurality of conductive elements (132) disposed inside a hollow cavity (128) used to embed two magnetic cores (134, 136). The conductive elements (132) encircle three sides of the embedded cores (134, 136) and interface with a multilayer PCB (137) which includes conductive traces formed therein to encircle a fourth side of the embedded cores and to form primary and secondary winding circuits.
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Citations
37 Claims
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1. An embedded core transformer comprising:
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a base enclosure having a base wall and a perimeter wall forming a cavity with an open top; a magnetic core disposed inside the cavity comprising a volume of magnetic material formed as a closed magnetic circuit having a plurality of magnetic circuit legs; a plurality of conductive winding elements disposed inside the cavity, each comprising a conductive sheet metal element formed to partially encircle one of the magnetic circuit legs, wherein each conductive sheet metal element includes three legs with two of the three legs formed to extend above the perimeter wall through the open top; means, sized to attach to the perimeter wall for closing the open top, for electrically interconnecting with each winding element by connecting with the two legs that extend above the perimeter wall and further configured with first conductive traces for forming a primary winding circuit that includes a first portion of the winding elements and second conductive traces for forming a secondary winding circuit that includes a remaining portion of the winding elements; and
,wherein the primary winding circuit is inductively coupled with the secondary winding circuit through the magnetic core. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An embedded core transformer comprising:
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a base enclosure formed by a base wall and a perimeter wall extending substantially orthogonally from the base wall thereby forming a cavity with an open top; a magnetic core, disposed inside the cavity, comprising one or more volumes of magnetic material formed in one or more closed magnetic loops with each closed magnetic loop having a plurality of magnetic circuit legs; a plurality of winding elements each comprising a layer of conductive sheet metal formed with a substantially horizontal leg, for providing a conductive path between the base wall and one of the plurality of magnetic circuit legs, and two opposing vertical legs formed integral with the horizontal leg and disposed on opposing sides of one of the plurality of magnetic circuit legs for partially encircling one of the plurality of magnetic circuit legs and wherein each of the vertical legs is formed long enough to extend above a height of the magnetic core and the perimeter wall and is further formed with a top section for engaging with a slot; and
,an interconnecting means comprising a plurality of conductive layers each including conductive traces and a plurality of dielectric layers separating and electrically isolating the conductive layers, wherein the interconnecting means attaches to the perimeter wall, and is formed with perimeter dimensions equal to or exceeding perimeter dimensions of the perimeter wall to thereby close the cavity, wherein the interconnecting means includes a plurality of slots passing completely there through and disposed to engage with the top section of each vertical leg for electrically interconnecting each of the winding elements with one or more of the conductive layers, wherein the interconnecting means comprises a plurality of first conductive traces positioned to combine with each of the winding elements to encircle one of the plurality of magnetic circuit legs with a continuous conductive turn, and with a plurality of second conductive traces for electrically interconnecting a first portion of the winding elements to form one or more primary winding circuits and with plurality of third conductive traces for electrically interconnecting a second portion of the winding elements to form one or more secondary winding circuits. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A method for forming an embedded core transformer comprising the steps of:
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forming a plurality of sheet metal stampings each comprising a group of winding elements with each winding element comprising a horizontal leg integrally formed with two opposing vertical legs and a connecting bar joining the group of winding elements together for easy handling; positioning each of the plurality of groups of winding elements into a cavity formed by a base enclosure comprising a substantially horizontal base wall and a perimeter wall extending vertically from a perimeter of the base wall, fastening the plurality of groups of winding elements in predetermined locations inside the cavity with the vertical legs of each group of winding elements extending above the perimeter wall and removing the connecting bar from each group or winding elements; positioning one or more magnetic cores, each comprising a closed magnetic circuit having a plurality of magnetic circuit legs, into the cavity with each magnetic circuit leg positioned between vertical legs of appropriate groups of winding elements; forming an interconnecting means having a plurality of apertures formed there through with each aperture positioned to engage with one of the vertical legs extending above the perimeter wall, further forming the interconnecting means with conductive traces suitable for connecting a first portion of the plurality of winding elements together in a primary winding circuit and a second portion of the plurality of winding elements together in a secondary winding circuit; engaging each of the plurality apertures with one of the vertical legs and attaching the printed circuit board to the perimeter wall; and
,attaching each of the vertical legs to the interconnecting means. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification