High frequency winding design for planar switch mode transformers

Switch mode power supplies as a mass produced article leave room for optimization especially at the voluminous magnetic components. Hereby planar component designs can reduce the overall height of the power supply and give it a more compact design. Since cores are available in standard sizes the optimal winding layout has to be found. Due to increased parasitic capacitance interleaving is not a good option to reduce losses in the windings at high frequency resonant power supplies. This article presents and evaluates different winding designs for resonant switch mode transformers operating in power supplies with frequencies larger than 500kHz. This article shows that the revolved parallel design performs best of the tested designs under the given conditions. In addition, the revolved design can compete with solutions as planar litz when it comes to value meaning cost and production complexity. Furthermore, the article shows the abilities of a heat measurement prototype.