Cores stressed to higher B will self-heat, reducing Bsat for ferrites and some other materials.
This core loss has a positive temperature coefficient at the upper end of the temperature range in most materials - setting up the potential for thermal run-away.
Cores heated by their windings will also show reduced Bsat and similar temperature problems.
For simple 'DC' transformers this may be true. Avoiding core saturation is only of primary importance in saturation-limited designs, where minimal support of volt-second withstand is provided at a minimum operating frequency.
Throughput power is typically increased for a fixed core size when higher frequency operation is permitted and core loss limits are probed.
If your topology is saturation-limited, it's only natural to investigate possible improvements available using other materials that exhibit a higher saturation limit - to see if the altered core loss effects of the different materials are over-ridingly detrimental.
Alternately, if your circuit uses resonances to regulate power throughput, you might consider operating more consistently above resonance or at higher resonant frequencies.
On a sunny day (Sat, 13 Jun 2009 14:18:10 -0500) it happened "Tim Williams" wrote in :
If a transformer winding has a DC component, then a gapped core may be needed. A typical example of old were the filter chokes in the tube DC supplies, and the class A audio output transformers, gap to prevent core saturation. Horizontal output transformers [] cores for TVs always had air gaps too. I'd imagine that with ferrite ring-cores there is enough other stuff then iron in teh mixture to double as 'air gap', but then again... Any idea?
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