for example we have a buck converter with 10amps output current and 0.5amps ripple current at 200Khz.Core losses are invariably larger than estimated - we have designed a lot of buck and similar converters
core losses from off the shelf inductors are actually very poor - we need to oversize significantly to get reasonable losses esp above 50kHz
high AC ripple of current ( and hence flux ) is the big killer here, along with Rdc ...
yes but that graph is "peak ac flux density VS core loss"but what about dc bias condition?i think that graph isn't useful for calculate losses due to dc bias or dc magnetizing.am i right?Hi,
You could use the core loss density graph presented for the core material. Trace the loss density at your switching frequency and multiply it by the core volume to get the core loss.
What you need to do is to determine the actual material, then look for a datasheet for that material so you could trace the graph to obtain the core loss density value.
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Since you already have the datasheet, then you could post a link to the datasheet here.
https://selfelectronic.net/wp-content/uploads/2017/10/06.pdfPlease post a link to the datasheet.
I couldn't open the pdf and the website is not very good looking.
for example we have a buck converter with 10amps output current and 0.5amps ripple current at 200Khz.
you mean DC term of 10Amps didn't produce losses in core?(or is negligible)and that 0.5Amps ripple is cause of core losses?
Core losses result only from AC excitation. DC bias applied to any core does not cause any core losses, regardless of the magnitude of the bias.
DC current affects permeability and actual inductance. You need to take care that the core isn't saturated.
if AC ripple current produce loss in core then can we decrease loss by increasing wire turn resault in increasing inductance and decreasing ripple current?!!
Not necessarily because additional turns increases the magnetic field change (thus core losses) for a given ripple amplitude. I guess I'm not sure of that exact relationship but increasing turns also adds wire which also increases restive losses. So for a given inductor size there is always a sweet spot for inductor value vs efficiency.
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