Gapped Ferrite Transformer

[babinton]

Hello,

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.)

Regards.

 

[andre_luis]

There is no restriction regarding topology involved.

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[Orson Cart]

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.

 

[babinton]

Thanks orson cart

 

[andre_luis]

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.

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[Orson Cart]

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.