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Fabrication of High-Frequency Transformers With Programmable Windings

IP.com Disclosure Number: IPCOM000046799D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 68K

Publishing Venue

IBM

Related People

Dobberstein, EA: AUTHOR

Abstract

Described is a method for constructing power supply magnetics, traditionally done by winding turns on a bobbin or toroid, which uses a common set of components and printed circuit programming to meet the design specifications. High-frequency (10 KHz-100 KHz) power transformers and inductors historically follow a traditional construction pattern. Turns of enamelled wire are wound on a bobbin which is then installed over an "E"-shaped ferrite core. The tips of the "E" are bridged by an "I" bar, or another "E"-shaped ferrite, and the assembly is held together by a channel frame which is also used to mount the unit to the next level assembly. Alternate construction employs a toroidal core to achieve a flatter geometry, but is more complicated to wind.

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Fabrication of High-Frequency Transformers With Programmable Windings

Described is a method for constructing power supply magnetics, traditionally done by winding turns on a bobbin or toroid, which uses a common set of components and printed circuit programming to meet the design specifications. High-frequency (10 KHz-100 KHz) power transformers and inductors historically follow a traditional construction pattern. Turns of enamelled wire are wound on a bobbin which is then installed over an "E"-shaped ferrite core. The tips of the "E" are bridged by an "I" bar, or another "E"-shaped ferrite, and the assembly is held together by a channel frame which is also used to mount the unit to the next level assembly. Alternate construction employs a toroidal core to achieve a flatter geometry, but is more complicated to wind. Although traditional construction is effective in producing a compact and efficient component, the form factor is rather cubic, preventing such desirable power supply form factors such as a "textbook" shape. The evolution of power supplies for electronic equipment has created an environment of many different types of multi-voltage supplies with various loading requirements. Each usually requires the release of a customized magnetic component with a unique set of turns and the associated control documentation that supports each new part number. These problems are precluded by the following technique. Fig. 1 shows the construction of a transformer or inductor according to this new technique. An insulated core basket constructed of a plastic material with good high-voltage dielectric strength is seated in a designated location on a printed circuit board. Alignment holes in the board and locating tabs molded into the basket can be used to facilitate orientation. A ferrite core is then laid into the basket; plastic snap-in retainers are placed over the core and basket assembly and pressed through mating holes in the photoconductor board until they snap in, locking the assembly to the board. A set of winding cages, as many as one for each side of the core, is placed over the core and basket assembly with the protruding cage wires inserted into mating plated-through holes in the photoconductor board. These plated-through holes represent the terminals of printed circuitry on the board. Other components are then inserted in the photoconductor board, and the entire assembly is wave- soldered to form a higher level power supply assembly. The winding cages comprise U-shaped wires, electrically isolated from each other and held in position by an encapsulating dielectric material (typically, a winding cage consists of 24 wires and resembles a segment of multi-conductor flat cable formed about a U-shaped mandrel). The subject construction technique can be extended to other geometries, such as exemplified by Fig. 2. The advantage of this approach is the technique by which the wires of the winding cages can be interconnected by the pho...