I have designed fly-backs and inductors and understand the basics about flux density, saturation and core losses. What I have never been very clear on is design of SMPS transformers. I get the concept that ideally you want to transformer to not hold any magnetic energy and instead to transfer it all, but what material properties allow this?
I’m assuming you want to have a high permittivity \$\mu_o\$ to transfer flux better but also a linear \$\mu_o\$ so there is a linear transfer of energy, what else? I have spent time over the years looking for good tutorials or information on this topic and never found anything very complete, there is a lot of information on inductors, or sometimes the application is not really clear but someone with a bit of experience can discern between true transformer design vs inductor based on if the design holds a lot of flux?
For instance I want to design an impedance matching transformer (1:3 step-up) for driving a load at ~300khz. I’m having a hard time selecting core materials, I was going to use a toroid because they are readily available but most of them are metal power instead of true ferrite. I know that metal powder “can work” but what properties of it should one look for it to be more ideal then other metal powder.
For reference I have posted images of some metal powder cores provided by Micrometals, For a high current inductor I would pick the -2 material, but for a transformer what would I want the \$\mu_o\$ curve to look like, and what is a good B-H curve for a transformer vs. inductor?
I guess my real question is, does anyone know of a book or good resource for high frequency transformer design that also goes into material property selection?