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Magnetic Field Distribution of a Rod Carrying Current

Posted Nov 2, 2014, 1:04 p.m. EST Low-Frequency Electromagnetics Version 4.4 3 Replies

Tianyu Dong
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Hello all,
I encounter the "Singularity matrix" error when I use the Magnetic and Electric Field module to calculate the magnetic field and potential distributions of a single rod. The model is quite simple, which consists of a conductive cylinder surrounded by an air sphere. I use Terminal and Ground under the default Magnetic Insulation node, and it gives the error I mentioned in the beginning. How can I excite the rod, i.e., a current input at the top surface of the rod and maybe a ground or a sink on the bottom surface?

Thanks,
Tony
3 Replies Last Post Nov 3, 2014, 4:25 a.m. EST
Dima Apter
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Posted: 1 decade ago Nov 3, 2014, 3:02 a.m. EST
Hi Tony,

You cannot just surround the rod by an air sphere an define a current flow through it. You need to close the loop for the current flow or to take the rod terminals to the outer surface of the surrounding air domain. The latter is shown in the attached model. Is that what you tried to do?

Best Regards,
Dima.

--
Dima Apter
A2Z Consulting Ltd.
www.a2z-consulting.com
Hi Tony, You cannot just surround the rod by an air sphere an define a current flow through it. You need to close the loop for the current flow or to take the rod terminals to the outer surface of the surrounding air domain. The latter is shown in the attached model. Is that what you tried to do? Best Regards, Dima. -- Dima Apter A2Z Consulting Ltd. www.a2z-consulting.com

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Tianyu Dong
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Posted: 1 decade ago Nov 3, 2014, 3:58 a.m. EST
Thanks Dima,

Well, I know that your model works well as the model shown here (www.comsol.com/model/integrated-square-shaped-spiral-inductor-129). In the model, can the infinite domain be applied when the conductor contacts the outer boundary of the air box? In addition, if the conductor system is complicated, i.e., both the source and the sink are located somewhere inside the model such as inside a coil. The geometry is not a loop, and I know the input current on the source surface and the voltage potential on the sink surface, then how can I excite the conductor?

Regards,
Tony
Thanks Dima, Well, I know that your model works well as the model shown here (http://www.comsol.com/model/integrated-square-shaped-spiral-inductor-129). In the model, can the infinite domain be applied when the conductor contacts the outer boundary of the air box? In addition, if the conductor system is complicated, i.e., both the source and the sink are located somewhere inside the model such as inside a coil. The geometry is not a loop, and I know the input current on the source surface and the voltage potential on the sink surface, then how can I excite the conductor? Regards, Tony
Dima Apter
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Posted: 1 decade ago Nov 3, 2014, 4:25 a.m. EST
In the model, can the infinite domain be applied when the conductor contacts the outer boundary of the air box?

I guess it's impossible.

In addition, if the conductor system is complicated, i.e., both the source and the sink are located somewhere inside the model such as inside a coil. The geometry is not a loop, and I know the input current on the source surface and the voltage potential on the sink surface, then how can I excite the conductor?

I don't think there is another solution except the two mentioned above. Electric current cannot appear from the space and enter the conductor.
Hence, the loop should be closed. Maybe you can shorten the two terminals with another conductor. You can play with this conductor geometry in order to minimize its effect on the magnetic field distribution in the relevant region. You can use Lumped Port or Single-Turn coil (in MF interface) to excite the conductor.

Best Regards,
Dima.


--
Dima Apter
A2Z Consulting Ltd.
www.a2z-consulting.com
[QUOTE]In the model, can the infinite domain be applied when the conductor contacts the outer boundary of the air box? [/QUOTE] I guess it's impossible. [QUOTE] In addition, if the conductor system is complicated, i.e., both the source and the sink are located somewhere inside the model such as inside a coil. The geometry is not a loop, and I know the input current on the source surface and the voltage potential on the sink surface, then how can I excite the conductor? [/QUOTE] I don't think there is another solution except the two mentioned above. Electric current cannot appear from the space and enter the conductor. Hence, the loop should be closed. Maybe you can shorten the two terminals with another conductor. You can play with this conductor geometry in order to minimize its effect on the magnetic field distribution in the relevant region. You can use Lumped Port or Single-Turn coil (in MF interface) to excite the conductor. Best Regards, Dima. -- Dima Apter A2Z Consulting Ltd. www.a2z-consulting.com

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