The Use of Foil and Litz Wire in SMPS Transformers

Jacob Campbell, Lead Engineer - Magnetics, West Coast Magnetic

The push to higher frequencies in SMPS power conversion is often limited by winding loss.  Both copper foil and litz wire windings can be a good choice because, in addition to low winding losses, in many cases, they provide high isolation and can be wound to have low leakage and tight coupling between the primary and secondary.  For purposes of this presentation we examined three transformer types, a step-up transformer, a step-down transformer and a one to one transformer, each wound with different litz wires and different copper thicknesses with the aim of determining which configuration was preferred from a loss and a cost perspective. Since frequency of operation is also an important variable, we also looked at performance at 100 kHz, 200 kHz, and 500 kHz.

Jacob received his B.S. degree in Mechanical Engineering from the University of the Pacific in May 2018. He contributes a mechanical-oriented skillset to design work for WCM custom inductor and transformer projects and utilizes every opportunity to further his knowledge of electromagnetic technology.  Jacob is a private pilot, a hobby which complements his mechanical engineering background.

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