Re: [femm] periodic boundary condition problem

[Jiri Vecerka <vecerkaj@xxxxxxxxx>]

Just a note. If you want to calculate torque in
dependence on the angle of rotation (whether with
stator current or not) you will get a problem how to
rotate the rotor (because the contour for the torque
calculation should be away from a boundary).
Sometimes its easier way to calculate entire machine
and simply rotate.


Jiri Vecerka

> 
> Another issue that the original poster may have is
> how to apply these 
> boundary conditions within the program. Unlike
> "regular" boundary 
> conditions, which can be applied to as many
> different arcs or segments 
> or combinations thereof, the periodic boundary
> conditions are special in 
> that they can only be applied to either two line
> segments or two arc 
> segments, and each component of the pair of segments
> or line segments 
> must have the same length. For example, if the edge
> that you wanted to 
> make (anti)periodic was composed of 5 line segments,
> you'd have to 
> define 5 (anti)periodic boundary conditions and
> apply one to each of the 
> segments on the edge and its mate on the adjoining
> boundary.
> 
> Perhaps all of this would be clearer with an
> example. I've attached 
> pole's worth of a four pole PMSM (which is actually
> cribbed from 
> Quickfield's Magn4 example). Antiperiodic boundary
> conditions are used 
> so that only the one pole need be modeled. I've
> defined all the parts 
> in the rotor to be in group number one, so that the
> rotor can be turned, 
> if desired.
> 
> Dave.
> 
> --


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