Amidon T200-2 core suitability for 1kWrms?

[jwagnerhki]

Hi,

ok the simplest way of course would be to plug one in and try it out, but our mosfet bridge design is still a proto and doesn't go beyound a few 100W yet, so...

Two questions to you class D output inductor design gurus here:

- do you know if the Amidon T200-2 or T200-6 non-gapped toroidal powdered iron core is useable in 1000Wrms (4ohm) ~400kHz class D applications, too, as opposed to their traditional use in multi-kW RF applications?

- how well are gapped toroidal cores really suited for >500Wrms output inductors? do they leak just too much or are they still useable?

- Jan

[Genomerics]

No, is the simple answer.

However, since you have asked the question I felt the need to try and explain how to design filter inductors.... it's something I'll need to try sometime so this seems like a good time to start.

The beginning is at

http://www.genomerics.org/inductors/inductors.html

Don't get too excited.... I'll let you know when there is actually something worth reading. In the mean time I'm just playing.

Cheers

DNA

[Eva]

I can only find permeability figures for those cores, being 12nH/turn^2 for T200-2 and 10nH/turn^2 for T200-6. That would give suitable inductance values around 30uH with 50 turns, but I can't find data on energy storage capabilities and core losses versus frequency and flux density.

As a reference, I have standard yellow-white iron-powder cores of similar dimensions whose permeability is around 200nH/turn and whose measured energy storage capability is 8mJ (.5*L*Isat^2). That energy storage figure seems quite insufficient for most applications, and these cores will become quite hot if even operated above 50Khz, so I'm sticking to gapped ferrite inductors. However, the Amidon ones feature much lower permeability so they should feature considerably higher energy storage figures and lower losses allowing for operation at higher frequencies.

By the way, could anybody recommend me affordable iron powder materials with high energy storage capabilities? High frequency operation is not a requirement for some of my projects.

[Genomerics]

That's the old...... 'Not enough useful Data' problem.

I'm not certain but I think you might find that Arnold are doing lots of business because they provide 'useful' data.

Arnold

You might find that companies that provide finished products use a lot of this stuff.

Interpreting it is another thing, it is in there somewhere though. Would be nice to have some idea of thermal resistances.

Cheers

DNA

[Eva]

I'm used to work without data. I use to buy cores here and there and characterize them myself, altough it's time and money consuming.

BTW: Thanks for the link to such a detailed catalog.

[BV]

Maybe some informations you can find here:
http://www.micrometals.com/

[Genomerics]

Next page is up. First part of the Magic Sum.

First page has some links on it for good data.

It's linked on the front page under Other Bits, Filter Inductor Design.

Genomerics

Cheers

DNA

[jwagnerhki]

Thanks everyone for your input!

Micrometals.com indeed had some "specs", http://www.micrometals.com/appnotes/...s/ipcs4rfp.pdf. Page 9 figure K says T200-2 (material 2) is supposed to have a "power rating" of 800W @ 1..2 MHz (for 25degC temp rise due to core losses). OTOH, figure D there claims ~3000gauss 500kHz => 0.5W/cm^3 core losses - 0.5 seems ok, AFAIK comparable to power ferrite...!

http://toroids.info/T200-2.asp : Material = Carbonyl E. More googling on that material yielded "high volume resistivity", "rf inductors", "resonant inductors above 50kHz".

And further, this looks actually quite good for T-200-2: http://www.41hz.com/downloads/TA2022.pdf : Page 22: "Tripath recommends that the customer use a toroidal inductor with a Carbonyl-E core for all applications of the TA2022."

In that TA2022 tech info paper, Tripath has used and recommends the significantly smaller core T68-2, for ~100W. So I'd guess the T-200-2 should be suitable, and capable to pack a lot more of them little watts

Anyways. The Arnolds pdf is very comprehensive, too, thanks for the link!

Your genomerics.org inductor design page is nice. plus has some attitude there... Hmm - somehow reminds of sci.electronics.design DNA / Genome. Btw there is also some sort of automatic calculation that selects suitable inductor cores, not sure but you might find it useful/interesting: http://schmidt-walter.fbe.fh-darmsta...smps_in_e.html
with infos http://schmidt-walter.fbe.fh-darmsta...d_hilfe_e.html

[Bgt]

my coldamps uses also T200-2 like toroids, they dont get very hot during use. And they are rated 400W at 4ohms and 800 bridged. So wonder what they use?

[jwagnerhki]

grr, mixup with materials... All reads in the TA2022 pdf, didn't read it too closely the first time.

Amidon's carbonyl E is apparently material -06 and not -2, so the core might actually be T200-6 (or, hmm!? old -2 but new -06? go figure ). and not T200-2. And Micrometals carbonyl E material code is -2 (e.g. T94-2). Wouldn't be the least bit surprised if the color codes were different, too, at least for ferrite toroids the colors mean zip...

But odd that many x kW <3MHz RF baluns use the T200-2. So, hmm... dammit, this has me confused...

Wrt "T200-2 like toroids", good observation there Not sure, but from http://www.coldamp.com/opencms/opencms/coldamp/en/ it seems this is painted wine red. Amidon pages at http://www.amidoncorp.com/aai_ironpowdercores.htm say T200-2 color is red. /Might/ be a T200-2, then, provided the core is from Amidon. Argh. So if coldamp also maybe uses T200-2.. Oh well, I'll just have to buy one of those T200-2's or a smaller -2'one and give it a try!