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Time dependent study and multi-turn coils

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Dear Sir or Maddam,

i´m trying to investigate the resulting eddy currents in the walls of a rf shielding chamber created by magnetic coils located inside of the chamber, these coils will be excited by current ramps. To do this, i´m using Comsol 5.1 and currently trying to run a 3D simulation since there wouldnt be much rotation symmetry in the later setup to do this by a 2D simulation.
I started the study by setting up everything according to the stationary 3D helmholtz-coil tutorial (-->using the ACDC module) and changing it a little bit. The study only contains one multi-turn coil and two metal plates, embedded in a sphere. The stationary solution worked fine.
So under "components >> definitions" i added a ramp function and named it cr1. Then, in the "multi-turn coil" settings i edited the coil current from "I0" to "I0+(I0*cr1(t[1/s]))". When i try to solve this study, i always get the error message "Failed to find consistent initial values.
Matrix has zero on diagonal.
Last time step is not converged.
- Feature: Time-Dependent Solver 1 (sol3/t1)".

Then i tryed using a single-turn coil and excite the coil again by a ramp function using gap feed, but i get the same error message.

Now i´m kind of clueless how to go on and i guess i need some help since the error message is pretty useless for me.

Thank you guys for any help

3 Replies Last Post Jun 9, 2015, 8:56 a.m. EDT
Walter Frei COMSOL Employee

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Posted: 9 years ago Jun 8, 2015, 4:59 p.m. EDT
Dear Matthias,

The COMSOL Discussion forum is meant for informal discussions amongst the COMSOL user base, and you are certainly welcome to take advantage of it.

However, although COMSOL team members do occasionally post general responses here, COMSOL Technical Support is provided one-on-one to our on-subscription customer base via the COMSOL Support Center: www.comsol.com/support

Also, instructions for uploading large files for the support team are available here: www.comsol.com/support/knowledgebase/1098

Please feel free to re-post your questions to the Support Center if you are looking for a reply from the COMSOL Technical Support Team.
Dear Matthias, The COMSOL Discussion forum is meant for informal discussions amongst the COMSOL user base, and you are certainly welcome to take advantage of it. However, although COMSOL team members do occasionally post general responses here, COMSOL Technical Support is provided one-on-one to our on-subscription customer base via the COMSOL Support Center: http://www.comsol.com/support Also, instructions for uploading large files for the support team are available here: http://www.comsol.com/support/knowledgebase/1098 Please feel free to re-post your questions to the Support Center if you are looking for a reply from the COMSOL Technical Support Team.

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Posted: 9 years ago Jun 9, 2015, 1:30 a.m. EDT
Good morning,

thank you for your answer Walter. I rephrased the adress of welcome of my first post. Additionally i deleted the file link, and cleared the file from the containing solutions so i can upload it. I dont know if we have one-on-one support yet, since our main user who also aquired this CPU-locked license is not available by now.

Best Regards
Matthias
Good morning, thank you for your answer Walter. I rephrased the adress of welcome of my first post. Additionally i deleted the file link, and cleared the file from the containing solutions so i can upload it. I dont know if we have one-on-one support yet, since our main user who also aquired this CPU-locked license is not available by now. Best Regards Matthias


Walter Frei COMSOL Employee

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Posted: 9 years ago Jun 9, 2015, 8:56 a.m. EDT
Dear Matthias,

Since you have access to a CPU license, you (or any user within your organization) is certainly welcome to contact the COMSOL Technical Support Team directly.
Dear Matthias, Since you have access to a CPU license, you (or any user within your organization) is certainly welcome to contact the COMSOL Technical Support Team directly.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.