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Magnetic components (inductors and transformers), when present in power electronics converters, consist undoubtedly, along with the semiconductor switches, the main power loss contribution. This fact emerges the necessity of having some easily applicable tools for their effective resistance accurate calculation. The up to now widely used relative theoretical or empirical formulas have been extracted under assumptions or experimental conditions that invalidate their results over several application cases. Some lately released computer aided analyses, though useful, do not make it to escape from the strictly bounded logic and assumptions on which the previous formulas were based. In this paper a new expression for the calculation of high frequency copper losses in transformer and inductor coils with round conductors, more general than the existent models and without any of the traditionally imposed assumptions and limitations, is proposed and established by finite element analysis (FEA) and measurement results. No complicated tables with coefficient numerical values are necessary and the final formula extracted is simple and ready to use. Additional to this work, a comparison between the results determined by the existent theoretical analyses and FEA clarifies their discrepancy over specific ranges of the several parameters involved.
Date of Conference: 2-5 Sept. 2007