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Re: frequency vs core saturation



Original poster: scott <scottxs@xxxxxxxxxxx>

Tesla list wrote:

    Here is a question for all you mathy theoretical technical guys.

I guess that rules me out.

I heard In physics class tonight,

Tonight?

that if you use a higher frequency you can use a smaller core for a transformer. In my mind this means, if you use a higher frequency, you can pump more voltage through your primary, and consequently get more out of your secondary.

Lord have mercy!

is this beneficial in any way?  Is this even true, or is my logic flawed?

Kinda sorta.

Someone should point you to some fine website explaining magnetics. I lost the link. Anyways...

A current in a wire produces magneto-motive force, in MKS units, amps-meter. A magneto-motive force causes a magnetic flux density in a permeable material, proportionate to its reluctance, just like an electro-motive force (voltage) causes current in a resistive material proportional to its resistance.

Now, when you have a high-permeable material, you require less amp-meters of wire then if you have a low-permeable material. Therefore, your I-squared-R losses (copper-loss) is much less, and you can use reasonable & cheap semiconductor to switch the lower currents.

Perhaps the best way to think of it is in mechanical terms:
Work Done = Force X Distance.

Electronically,

Work Done = Amp-Meters X Magnetization

Now with transformers, every trip from + and - and - to + current is like a shovel of charge. So if you shovel a little bit of charge tens of thousands or millions of times per second, its much better than shoveling a lot more charge fewer times per second, especially since that takes lower-resistance, bigger expensive semiconductors.

Hope that helps.

Scott