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How to use the PI Expert magnetics designer results to bild a transfomer

Posted by: MichaSee on 10/14/2021


I used the PI Expert to calculate a flyback design with the InnoSwitch3-EP. I have some trouble to understand the results of the magnetics designer.
Doing the windings is no problem,but I don't understand, which core I have to by and how to "Gap the core halves to get 358 uH +- 5.0%."
The list og materials says:

Core: EFD20, 3F3, gapped for ALG of 96 nH / T^2

Do i have to by a core with 96nH? -> This is not possible. There are only 100nH cores availible.

What does it mean to "Gap the core halves to get 358 uH" in the building preperations?

Thanks in advance



Attachment Size
Design results 1.84 MB


Submitted by PI-Yoda on 10/15/2021

Hi Micha,

Inductance Factor, AL, is often stated by the manufacturer for pre-gapped ferrite cores.

AL = Inductance / Turns^2

You know the right side variables from your design and you can calculate the AL required.

It is unlikely to find the exact one you need in the datasheet. Manual adjustment still maybe required. 

Best Regards