Geometric-constants-based design of transformers for isolated switching converters

This paper discusses issues related to the design method of transformers for switching converters based on the use of the geometric constant K_gfe of magnetic cores. It is shown that some inherent assumptions in the application of the method can be misleading if the effects of specific combinations of geometric measures and thermal properties of the magnetic cores are not properly considered. An example regarding the design of the transformer for a low-power multi-output isolated dc-dc forward converter is presented and discussed.