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Rotating electrical machine symmetry

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Hello,

i set up a model of a rotating elctrical machine in 3D. So far the model is working, but i have a problem with the symmetry. I modeled 1/32 of the machine. If i rotate the rotor by several degree the field of the next sector seems to be missing or is in the wrong position. I attached 2 pictures to show you the problem. I think it has something to do with the sector symmetry, but i am not aware, what mistake i am doing.



6 Replies Last Post 4 apr 2018, 01:35 GMT-4

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Posted: 7 years ago 13 feb 2018, 08:54 GMT-5

Hi

did you use the "Sector Symmetry" for the sliding interface?

Cheers

Jens

Hi did you use the "Sector Symmetry" for the sliding interface? Cheers Jens

Magnus Olsson COMSOL Employee

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Posted: 7 years ago 13 feb 2018, 08:56 GMT-5

Hi Seb,

There are several ways things may go wrong. I would check the following:

1) Use weak constraints in the settings for sector symmetry. 2) Make sure that you have periodic condition settings that are compatible with the sector symmetry (periodic/antiperiodic). 3) On the identity pair, make sure that source and destination frames are spatial.

Best regards, Magnus

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Magnus
Hi Seb, There are several ways things may go wrong. I would check the following: 1) Use weak constraints in the settings for sector symmetry. 2) Make sure that you have periodic condition settings that are compatible with the sector symmetry (periodic/antiperiodic). 3) On the identity pair, make sure that source and destination frames are spatial. Best regards, Magnus

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Posted: 7 years ago 13 feb 2018, 13:26 GMT-5

Thanks for the replies.

I use sector symmetry and checked your points, Magnus. What menas this axis of rotation in the sector symmetry node?

Thanks for the replies. I use sector symmetry and checked your points, Magnus. What menas this axis of rotation in the sector symmetry node?

Magnus Olsson COMSOL Employee

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Posted: 7 years ago 14 feb 2018, 04:03 GMT-5

The axis of rotation is a setting needed in 3D - in 2D it is always the out-of-plane direction. It should denote the axis direction around which the rotor is revolving. It is important that the sector symmetry boundaries, that is the boundaries of the identity pair, lie on a cylinder (or other body of revolution) with an axis that is pointing in the given "axis of rotation" direction. If there are inconsistencies, for example if the geometry was not properly drawn or the "axis of rotation" was set incorrectly, the rotor-stator coupling in the sector symmetry condition may fail. You can test this by making a surface plot of the expression "1/incontact_ap1". This should result in unity (1/1) on the identity pair boundaries and inf (1/0) that will not render on the other boundaries. If there is a problem, it will show up as transparent patches on the identity pair boundaries (some elements not rendering).

-------------------
Magnus
The axis of rotation is a setting needed in 3D - in 2D it is always the out-of-plane direction. It should denote the axis direction around which the rotor is revolving. It is important that the sector symmetry boundaries, that is the boundaries of the identity pair, lie on a cylinder (or other body of revolution) with an axis that is pointing in the given "axis of rotation" direction. If there are inconsistencies, for example if the geometry was not properly drawn or the "axis of rotation" was set incorrectly, the rotor-stator coupling in the sector symmetry condition may fail. You can test this by making a surface plot of the expression "1/incontact_ap1". This should result in unity (1/1) on the identity pair boundaries and inf (1/0) that will not render on the other boundaries. If there is a problem, it will show up as transparent patches on the identity pair boundaries (some elements not rendering).

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Posted: 7 years ago 14 feb 2018, 07:54 GMT-5
Updated: 7 years ago 14 feb 2018, 08:20 GMT-5

Hallo, i made a plot with the the expression. The first picture shows the identity pair (between U-core and the 4 magnets) and the second the plot with the expression. Obviously i made a mistake, when i applied the axis of rotation.

Is it possible to plot all of the sectors?

Hallo, i made a plot with the the expression. The first picture shows the identity pair (between U-core and the 4 magnets) and the second the plot with the expression. Obviously i made a mistake, when i applied the axis of rotation. Is it possible to plot all of the sectors?


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Posted: 7 years ago 4 apr 2018, 01:35 GMT-4

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