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Computation of coil induced magnetic field

Posted 14 set 2015, 05:49 GMT-4 Low-Frequency Electromagnetics, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.3 11 Replies

Alessandro Vicini
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Hullo everybody,

I need to simulate the magnetic field generated by an assembly of coils (geometry is 3D, not axisymmetric). To start with, I am just trying to simulate a single coil, which I model as a multi-turn coil domain, but I am not able to obtain the values of the B field which should be expected from analytical formulas. The far field is modeled as magnetic insulation.
If anyone can give me some hint it would be really welcome, thank you.

Alessandro
11 Replies Last Post 17 set 2015, 03:51 GMT-4
Ueli Hafner
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Posted: 9 years ago 14 set 2015, 07:49 GMT-4
Hi Alessandro,

in the Multi turn coil node there must be considered some settings:
1. set Coil-Type to circular
2. sub-node "coil geometry (maybe it a little bit different in version 4.3): choose an edge in the middle of the windings (ev. split the coil into two parts)
3. In the frequency domain peek values for the current are used.

I hope this hints can help you.

regards, Ueli
Hi Alessandro, in the Multi turn coil node there must be considered some settings: 1. set Coil-Type to circular 2. sub-node "coil geometry (maybe it a little bit different in version 4.3): choose an edge in the middle of the windings (ev. split the coil into two parts) 3. In the frequency domain peek values for the current are used. I hope this hints can help you. regards, Ueli
Alessandro Vicini
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Posted: 9 years ago 14 set 2015, 08:16 GMT-4

Hi Ueli,

thanks for your reply.
That's what I did: the coil is defined as circular, and I assign the value of the current circulating in it.
The reference edge is in the middle of the coil.
However, the values of B in the middle of the coil (on the symmetry axis) is approximately 50% lower that expected.

Regards,

Alessandro
Hi Ueli, thanks for your reply. That's what I did: the coil is defined as circular, and I assign the value of the current circulating in it. The reference edge is in the middle of the coil. However, the values of B in the middle of the coil (on the symmetry axis) is approximately 50% lower that expected. Regards, Alessandro
Ueli Hafner
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Posted: 9 years ago 14 set 2015, 08:31 GMT-4
Hi Alessandro,

can you post the geometrical values for the coil, the current and measured field or the model file?

regards, Ueli
Hi Alessandro, can you post the geometrical values for the coil, the current and measured field or the model file? regards, Ueli
Alessandro Vicini
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Posted: 9 years ago 14 set 2015, 09:03 GMT-4

Hi Ueli,

please find attached the model of the problem.

The expected value of the B field in the center of the coil along the axis is approximately 0.034T (the total current is 2697A, and the average radius is 0.05m; this is also confirmed by 2D axisymmetric analysis carried out with the FEMM software), but the value obtained is 0.02T.

Regards,

Alessandro
Hi Ueli, please find attached the model of the problem. The expected value of the B field in the center of the coil along the axis is approximately 0.034T (the total current is 2697A, and the average radius is 0.05m; this is also confirmed by 2D axisymmetric analysis carried out with the FEMM software), but the value obtained is 0.02T. Regards, Alessandro

Attachments:

Sergei Yushanov Certified Consultant
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Posted: 9 years ago 14 set 2015, 09:12 GMT-4
Alessandro,

Attached is model file with comparison to analytic solution.

Regards,
Sergei
Alessandro, Attached is model file with comparison to analytic solution. Regards, Sergei
Alessandro Vicini
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Posted: 9 years ago 14 set 2015, 09:17 GMT-4

Hullo Sergei, unfortunately I'm using version 4.3a of Comsol, so I am not able to open your model...

Regards,

Alessandro
Hullo Sergei, unfortunately I'm using version 4.3a of Comsol, so I am not able to open your model... Regards, Alessandro
Alessandro Vicini
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Posted: 9 years ago 14 set 2015, 10:34 GMT-4


Ok, I've just verified that it actually works if I carry out a 2D (axisymmetric) solution; the value obtained at the center is 0.032T.

With the 3D solution though, the same value is 0.02T. The coil is defined exactly in the same manner as a multi-turn coil; the only difference is that in 3d I have to define a reference edge, but the values obtained are wrong no matter if I choose the inner or outer radius of the coil.

Regards,

Alessandro
Ok, I've just verified that it actually works if I carry out a 2D (axisymmetric) solution; the value obtained at the center is 0.032T. With the 3D solution though, the same value is 0.02T. The coil is defined exactly in the same manner as a multi-turn coil; the only difference is that in 3d I have to define a reference edge, but the values obtained are wrong no matter if I choose the inner or outer radius of the coil. Regards, Alessandro
Sergei Yushanov Certified Consultant
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Posted: 9 years ago 14 set 2015, 10:47 GMT-4
Alessandro,

Make sure that mesh resolution is appropriate. The best way to do this is to draw coil axis line and set mesh size sub-node for this line. Refine mesh size and see how it changes the results.

Regards,
Sergei
Alessandro, Make sure that mesh resolution is appropriate. The best way to do this is to draw coil axis line and set mesh size sub-node for this line. Refine mesh size and see how it changes the results. Regards, Sergei
Alessandro Vicini
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Posted: 9 years ago 14 set 2015, 11:19 GMT-4

Alessandro,

Make sure that mesh resolution is appropriate. The best way to do this is to draw coil axis line and set mesh size sub-node for this line. Refine mesh size and see how it changes the results.

Regards,
Sergei


Hi Sergei,

yes I already tried mesh refinements, but with no substantial influence on the solution. I also tried what you suggest, by generating a very tiny cylinder along the axis line so as to control mesh size. Maximum value is still about 0.02T.

Regards,

Alessandro

[QUOTE] Alessandro, Make sure that mesh resolution is appropriate. The best way to do this is to draw coil axis line and set mesh size sub-node for this line. Refine mesh size and see how it changes the results. Regards, Sergei [/QUOTE] Hi Sergei, yes I already tried mesh refinements, but with no substantial influence on the solution. I also tried what you suggest, by generating a very tiny cylinder along the axis line so as to control mesh size. Maximum value is still about 0.02T. Regards, Alessandro
Sergei Yushanov Certified Consultant
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Posted: 9 years ago 14 set 2015, 12:02 GMT-4
Alessandro,

Attached is verification model in v.4.3.

Regards,
Sergei
Alessandro, Attached is verification model in v.4.3. Regards, Sergei
Alessandro Vicini
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Posted: 9 years ago 17 set 2015, 03:51 GMT-4

Thank you very much Sergei.
Thank you very much Sergei.

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