Re: [femm] torque computation

[David Meeker <dcm3c@xxxxxxxxxxxxx>]

Diego Perez Lara wrote:

> Dear all, I have some problems calculating torque of an induction
> motor. When i'm doing a harmonic analisys, femm doesn't take into
> account B-H curve and i put a linear mu, but i can't achieve a valid
> result. i'm simulating a quarter of the motor but if i rise up mu,
> induction is huge. Do you have any clue to solve problem?i'm
> calculating torque from stress maxwell's tensor across a centered
> curve round the airgap with a fine mesh in it. Thank you Diego Pérez

Induction motor designs sometimes have closed slots on the rotor. By
design, iron over the slot opening is very thin so that it saturates and
doesn't shunt flux away from paths that would link the rotor bars. To
analyze this sort of machine, femm a nonlinear time-harmonic formulation
needs to be implemented in femm, and it currently isn't. In the mean
time, the best that you can do is to analyze sort of an equivalent
machine with slot openings that would be sort of the equivalent of the
machine with the slot openings highly saturated.

Dave.
--
David Meeker
http://femm.berlios.de/dmeeker