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[FEMM] A little paradox with anti-periodic boundary condition and torque computation



Hello all,

I've attached two models of synchronous reluctance motor using anti-periodic boundary conditions
in order to reduce the area to be computed. So only a half part of the motor is drawn.
The second model is obtained from the first by rotating the rotor of 180 degree angle.
Since the rotor is symmetric, for the two models, the Bn and Ht-plot along the airgap arcsegment
in front of the rotor should be equal but with opposite sign.
For Bn, it seems to be verified, but not for Ht.
AJ integrals are the same for the two models but the Torques obtained from weighted stress tensor are not.
These torques was computed in taking the whole group n°2 (in the models) as area of integration.
So I'm wondering if there is any limitation in using anti-periodic boundary condition or if it's in
the torque computation that I should take some care.

I got the following result :
Model_1
AJ integral =  1.390088e+002 Henry Amp^2 / m    
Torque =  -3.040467e-002 N*m     /m
Model_2         
AJ integral =  1.389757e+002 Henry Amp^2  /m    
Torque =  6.750423e+001 N*m  /m

Could anyone explain me why Ht are not the same ?
Any help would be appreciated.
Best regards

Tsarafidy
 


Attachment: models.zip
Description: Zip compressed data