Re: [FEMM] Solenoid charge

[David Meeker <dmeeker@xxxxxxxx>]

yanze wuan wrote:

> Dear all,
> my problem is to simulate a solenoid charge by using both linear ramp 
> of current and saw periodic shaped current profile. The calculaton 
> should take  into account the losses in coil and skin effect.
> Can somebody suggest any way to evaluate filed, current density 
> distribution and losses by using femm and or lua ?
>
> Thanks Wuan

As long as the materials are linear, you can break a periodic problem up 
into a series of problems at different frequencies and superimpose the 
results.  For example, if you have a saw wave that goes from 0  to 1 
with a period of T, the  waveform could be represented by a DC problem 
with an amplitude of 1/2, plus the sum  of AC problems with a current 
of: -(Sin[(2*n*Pi*t)/T]/(n*Pi)) for n from 1 to infinity.  In terms of 
FEMM's time harmonic representation, that would be a currents of 
amplitude of j*(1/(n*Pi)) at a frequencies of (n/T) Hz.


--
David Meeker
dmeeker@xxxxxxxx
http://femm.berlios.de/dmeeker