Flux density in an LLC core

Piotr Wyderski · 2018-09-30T22:06:11+00:00

Various application notes on LLC design consistently assume some maximal deltaB in order to calculate the number of primary turns. They take 200mT, sometimes ~400mT. But then they correct mu of the core by introducing a gap (most often) or a low permeability shunt in the case of the hi-tech planar transformers. This is to adjust Lm to the desired value. Clear. No, not exactly, the sequence of events is pretty mysterious. Gapping the ferrite decreases its Bpeak considerably, so what's the point in limiting oneself to 400mT from the very beginning? I see no post-gapping core losses correction calculation stage. Why is that? Best regards, Piotr

Sep 30, 2018 20 Replies

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piglet 8 years ago

I spoke to Snelling on the phone in about 1978. I phoned for applications advice and got put through to him. He was very superior, unfriendly and unhelpful.

piglet

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