Finding inductance and core loss for a powered iron torroid inductor in an "2TFC" SMPS

[zenerbjt]

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Hi,
Would you agree that the following PFC application note calculates the wrong value for core loss?

PFC Application note:

https://www.infineon.com/dgdl/InfineonApplicationNote_PFCCCMBoostConverterDesignGuide-AN-v02_00-EN.pdf?fileId=5546d4624a56eed8014a62c75a923b05

It concerns the equation for calculating B at the top of page 7.
The values for a,b,c,d,e, and x are wrong?

They should be as at page 72 of this below, or am I missing something?

https://www.mag-inc.com/Media/Magnetics/File-Library/Product%20Literature/Powder%20Core%20Literature/Magnetics-Powder-Core-Catalog-2020.pdf?ext=.pdf

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[FvM]

As mentioned before fitting parameters in Magnetics catalogs are often changed between issues. A different parameter set isn't necessarily wrong, as long as it results in a similar loss order of magnitude.

 

[zenerbjt]

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Thanks, What is the maximum flux density use-able with "Kool Mu" inductors?

Page 9 of the following Mag-Inc powder core catalog says that “kool mu” material has a saturation flux density of 1 Tesla.
So why does the "Kool Mu" B vs H graph on page 48 only show flux densitys up to 550mT?

Mag-Inc powder core catalog

https://www.mag-inc.com/Media/Magnetics/File-Library/Product%20Literature/Powder%20Core%20Literature/2017-Magnetics-Powder-Core-Catalog.pdf

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[Easy peasy]

Maximum "useable" flux density depends on: ability of ckt to handle the lowered Ur, the flux ripple at or about that peak flux, temperature, and the cooling available ...

--- Updated Dec 27, 2020 ---

Notice the saturation B = 1.0 Tesla, you may have read the 550 mW/cc @ 100kHz, 1000 Gauss ( 0.1 Tesla ac peak )

--- Updated Dec 27, 2020 ---

You can see from the graph, p48 that 1T requires likely more than 1000 A-t / cm - so getting up to high levels of applied H.

--- Updated Dec 27, 2020 ---

you can see above for Kool mu at H = 1000 Oe = 79600 A-t / m = 796 A-t/cm, the residual permeability is very low for all grades and the thing is tending towards being an air cored magnetic ...

 

[zenerbjt]

Thanks, i see what you mean, from that, i believe we would not want to operate kool mu at much above 100 A.t/cm

 

[Easy peasy]

Indeed, the -26 grade has only dropped to ~ 82% at 100 Oe ( = H of 7960, = 796.0 A-t/cm ) wheras grade -60 has dropped to ~ 47%