The difference between air-wound and ferrite inductors

Inductors

Hi

Properly a simple question, but what is the difference between air-wound inductors and ferrite inductors rearding power handling?

My guess is that it has something to do with the saturation, but I am not sure, hope someone can help.

thx

Re: Inductors

The core does not play a role in the power handling rating.
What it does, is it increases the inductance.
The core can saturate if the flux swing is too great. The core can add more power dissipation, which depends on the operating frequency and the flux swing.
But generally, when you talk about power dissipation capability you refer to the total power (winding plus core; note that the core dissipates nothing if only DC is flowing through the inductor) the inductor can dissipate with a reasonable temperature rise. Usually, this temperature rise is 40°C.

So usually, when we say an inductor can dissipate 1W, we mean that its temperature rise will be less than 40°C. Where that 1W is coming from does not matter, whether from the winding or the core.

DC current rating is mainly derived from the same requirement of maximum temperature rise and it means that the DC resistance of the inductor, multiplied by the square of the current produces a power dissipation that causes the temperaure to increase by no more than 40°C.

This is actually a good way of knowing the power capability of an inductor, since it is ususally not given in catalogs:
Find the DC resistance and the maximum allowable DC current.
Calculate that power. That is the power that the inductor can tolerate while its temperature rises by 40°C.
So now you know the power and you can choose how to distribute it between the core and the winding.

Inductors

Inductor for AC uses air core.
Inductor with Ac and DC uses ferrite cores.
Well ferrite cores saturates at some level, after that their performance is like a air core coil. Magnetism is bigger if ferrite cores.