There aren't many places where a mediocre Q-factor is useful.
Certain powdered irons (namely #26 and #52) are too lossy to use in most, say, flyback converter applications. But they're not so lossy that they just go "thud", so you still need a damper or snubber to absorb the ring-down EMI.
Actually, it's pretty close, I've done it before. Sooo lossy...
Anyway, that's the same as hooking a big fat resistor across the winding. It's not a high-frequency-only thing, like an R+C damper. It's just... lossy.
An application where efficiency doesn't matter, like my recent current limiting circuit breaker device, benefits from losses to the extent that:
- It doesn't cut into accuracy of the current limit (a solid-iron core would be dominantly resistive, and not really do any filtering anymore);
- Any loss in the core is loss I don't have to handle elsewhere (in transistors, resistors, TVSs, etc.). More components handling more power = more cost. Anywhere I can economize is a win.
This is a good application for something like a #26 powdered iron, instead of a gapped ferrite core.
If you're using a pot core, it sounds like you're already well above the point where anything like this can apply.
So... maybe, sometimes -- but no?
Also, on the subject of both #26 toroids and 150V buck converters, you may be interested to see this?
formatting link
First tried a #26 here, cooked itself. Then a Kool-Mu, also cooked itself (but slower). Finally changed to gapped ferrite, just because I have a shitton of 'em. Now it runs quite cool, because, well, of course it does...
Tim
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/
"mook Jonhon" wrote in message
news:2jGXB.15850$lD5.9612@fx39.iad...
> Playing with a 150VDC buck design that requires 4mH inductance. 600mA
> output current. I'm designing it on a 2616 pot core in Intusoft
> Magnetics designer software. It telling me set the AL to ~ 450nh and
> ~85 turns. Its running at 150KHz.
>
> DC resistance is less than 1 ohm but AC resistance is something like 15
> ohms.
>
> The heat generated is not a problem but would the high AC resistance
> act like a snubber of sorts?
>
> Its estimated to have a loss at full load of about 400mW. this is
> tolerable.
>
> If excellent efficiency it not of highest concern is there a benefit to
> leaving the inductor with high AC winding resistance losses.
>
>
> The alternative is of course miltifilar, litz, or foil winding to bring
> the Rac and Rdc values closer together.
>
> thoughts?
>
>
>