Ae parameter for different transformer cores

Question

I am trying to select a transformer for designing a dc dc isolated forward converter. Now, I see in an example a core of ETD34 (AN 2013-03 application note from infineon,page 5).

Now, as partof the primary turns calculations, the formula is as shown below, there is a factor/term called as Ae.I have highlighted that factor there.

Now, it is assumed to be 97.1x10^-5 for ETD34 core. Why is such a core selected arbitrarily? Also, if I select a different core what will be the impact on the Ae parameter ? Also, what exactly is this Ae parameter ?

For example - if I use the transformer - transformer datasheet. How can I find the Bsat and the Ae parameter for it ? It is not specified.

Answer 1

Ae is a core parameter, not a transformer parameter. It's the effective area of the core.

The cross section changes a bit through the core, but if you use effective length for the length, and effective area for the area, you get the right results for that core, without having to do volume integration of the difficult shapes, the manufacturer has done it for you.