Femm calculations on rotating electrical machines

["dopo podo" <provo51@xxxxxxxxxxx>]

Dear users of Femm,

I am a novice in fem calculation. I have a question in relation to 
simulation of AC motors. As I understand it is not possible with Femm to 
calculate the entire behavior of rotating electrical machines. Could someone 
please explain why it is not possible (fundamental limitations?), and to 
what extend it can be made useful? If one uses a bought package like Cedrat 
? it appears to be possible (though they sell it at an impossible price). I 
would be very interested to know what is and what is not possible, 
preferably by explanation with an example.

Some thoughts boggling my mind are:
For instance if one would have a squirrel cage AC motor, one could model a 
part of the stator, put momentary currents in it related to a frozen instant 
in time (and assign a frequency (eg 60 Hz) for this domain???). One could 
model a rotor part, but what frequency would one have to fill in for that 
part (dependent on stator frequency and rotor speed). The currents in the 
rotor bars are a result from this calculation, they could not be given at 
forehand.
If one would have a PM-synchronous AC motor, one could draw a rotor and 
stator. For the rotor part it is all DC and for the stator it would be AC 
(eg 60 Hz). What would the frequency be to be filled in? Could Femm be used 
in any way to know more about the resulting fields (stator and rotor) in 
this machine running at a fixed speed?

Maybe some other would-be users have the same problems in that they don?t 
know exactly what can be done and what not.

If somebody were prepared to explain a little on this subject it would be 
very helpful.
Many thanks in advance.

John Cooper

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