I have a salvaged ferrite transformer with a tiny gap between its center legs, I want to know if I can use the transformer for a push-pull DC-DC converter of 250Watts power rating. ( the area product of the transformer shows that it can support the power level i want to design for.)
The centre leg gap will mean that the magnetising current will be greater than without a gap (i.e. lower primary inductance than for no gap) - and there will be some fringing flux from the gap - so you won't want solid wire or Cu foil near the gap where the heating from the fringing field would be noticeable. for your push-pull there will be more turn off current in the fets due to the lower Lpri - so make sure the pri wdgs are closely coupled to reduce voltage spiking on turn off - Regards, Orson Cart.
I´m surprised and never worried about this, designing the SMPS in the past.
Surelly, this phenomen may be predicted by core manufacturers, wich also design and provide the reel kit.
Hello andre, all of a cores parameters - gapped and ungapped - can be found on the data sheet usually, a high performance transformer has no gap, while a flyback will almost always have a gap as it has to store energy in the gap just like an inductor - Regards, Orson Cart.