[SI-LIST] Re: Why does lamination fail to prevent eddy currents at high frequencies?
- From: Steve Rogers <SRogers@xxxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Thu, 28 Mar 2002 08:36:27 -0000
First, Thanks to all who have replied,
Since my initial Email I have stumbled on a few new references. If my
understanding is correct (its often not) then the following may be a start
on whats going on.....
The normal text book approach to laminations and the improvements they make
to transformers etc is based upon a simple model which (really important
bit) does not consider the knock on effect of the eddy currents themselves!
In basic terms the simple text book stuff assumes that an eddy current
induced into a conductor does not have its own fields. Clearly this is total
and utter rubbish.
If we now find a decent book thats not full of what I call shielding-maths
(Maths put their in place of a good explanation of whats going on!The book
by GW Carter is a decent one). We find that the power loss associated with
the flux in a finite thickness block when the knock on effects are not
ignored, is a function of skin depth and thickness of the block! I have yet
to sit and read the beast in any depth but I guess that the conclusion may
be that laminations
will need to be a lot thinner than skin depth. If this is true then at
really high frequencies with very small skin depths the realisation of
laminations this thin will become a physical manufacturing problem
Thats todays input be it right, wrong or somwhere in the middle!
Any comments etc more than welcome
Thanks again
Steve Rogers
> RF Design Engineer
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