A Novel Planar Transformer Design Based on a Variable Width Winding

A. Savu(1*), C. Radoi(2), A. Florescu(3)

(1) University of Bucharest (P.U.B.), Romania
(2) University of Bucharest (P.U.B.), Romania
(3) University of Bucharest (P.U.B.), Romania
(*) Corresponding author

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The trend toward high power density, high operating frequency and low profile packaging in power converters will determine designers to replace the conventional Cu-wires transformers with planar transformers. In this paper a novel variable track width per turn design is proposed for the transformer windings. The basic design idea consists of matching the winding resistances per turn in order to maintain a flux balance among turns. The complete design methodologies for both variable and constant width windings are presented and compared. Theoretical design equations are confirmed using  a finite element analysis (FEA) simulation. A 10W half bridge LLC converter prototype has been constructed employing both winding structures. Experimental results show a 0.4% converter efficiency improvement using the novel planar transformer based on the new variable width design compared to the conventional constant width approach
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Planar Transformer; Variable Width Turns; Finite Element Analysis (FEA); LLC Converter

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