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How to inject an AC Current

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Howdy,

I have been working on a simulation where current is being injected into a medium through two electrodes. I realized that the current I was injecting was DC current. How do I inject AC current? I have the AC/DC module. I am currently trying to use a terminal to inject the current and putting a sinusoidal equation but keep getting errors. Any help is appreciated



9 Replies Last Post 26.03.2021, 13:48 GMT-4
Robert Koslover Certified Consultant

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Posted: 3 years ago 14.03.2021, 22:36 GMT-4
Updated: 3 years ago 14.03.2021, 22:37 GMT-4

When working in the frequency domain (which you seem to be), you don't specify a time domain style input of a sine function to represent the current. Instead, you specify a frequency and a port or other boundary condition (there are various options available) to launch the current. I think you may find some helpful examples in the applications library.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
When working in the frequency domain (which you seem to be), you don't specify a time domain style input of a sine function to represent the current. Instead, you specify a frequency and a port or other boundary condition (there are various options available) to launch the current. I think you may find some helpful examples in the applications library.

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Posted: 3 years ago 19.03.2021, 11:32 GMT-4

When working in the frequency domain (which you seem to be), you don't specify a time domain style input of a sine function to represent the current. Instead, you specify a frequency and a port or other boundary condition (there are various options available) to launch the current. I think you may find some helpful examples in the applications library.

Thank you for the quick response, I have been looking through some applications and haven't found exactly what im looking for. Do you have any recommended applications?

>When working in the frequency domain (which you seem to be), you don't specify a time domain style input of a sine function to represent the current. Instead, you specify a frequency and a port or other boundary condition (there are various options available) to launch the current. I think you may find some helpful examples in the applications library. Thank you for the quick response, I have been looking through some applications and haven't found exactly what im looking for. Do you have any recommended applications?

Robert Koslover Certified Consultant

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Posted: 3 years ago 19.03.2021, 12:29 GMT-4

Well, among others, consider the "inductor_3d" example, in the Application Library, under "Inductive Devices and Coils." You can also download the pdf description for that example, which is titled "Modeling of a 3D Inductor."

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Well, among others, consider the "inductor_3d" example, in the Application Library, under "Inductive Devices and Coils." You can also download the pdf description for that example, which is titled "Modeling of a 3D Inductor."

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Posted: 3 years ago 21.03.2021, 18:53 GMT-4

Well, among others, consider the "inductor_3d" example, in the Application Library, under "Inductive Devices and Coils." You can also download the pdf description for that example, which is titled "Modeling of a 3D Inductor."

Looking into the paper I see that the electrical ciruits Physics were used to create the AC Current source. Is there any way in the Electric Current Physics to create the AC Current?

>Well, among others, consider the "inductor_3d" example, in the Application Library, under "Inductive Devices and Coils." You can also download the pdf description for that example, which is titled "Modeling of a 3D Inductor." Looking into the paper I see that the electrical ciruits Physics were used to create the AC Current source. Is there any way in the Electric Current Physics to create the AC Current?

Robert Koslover Certified Consultant

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Posted: 3 years ago 21.03.2021, 20:40 GMT-4

I've attached another example. It's a simple current ring, driven by an AC lumped port. I hope this helps.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
I've attached another example. It's a simple current ring, driven by an AC lumped port. I hope this helps.


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Posted: 3 years ago 24.03.2021, 14:56 GMT-4

I've attached another example. It's a simple current ring, driven by an AC lumped port. I hope this helps.

Howdy, I was unable to open this file because I am currently running COMSOL 5.5. Is there any chance you have this example for COMSOL 5.5?

Thanks in advance

>I've attached another example. It's a simple current ring, driven by an AC lumped port. I hope this helps. Howdy, I was unable to open this file because I am currently running COMSOL 5.5. Is there any chance you have this example for COMSOL 5.5? Thanks in advance

Robert Koslover Certified Consultant

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Posted: 3 years ago 24.03.2021, 22:20 GMT-4

Here's a 5.5 version.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Here's a 5.5 version.


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Posted: 3 years ago 26.03.2021, 13:23 GMT-4

Here's a 5.5 version.

Howdy, Thank you for that. What I got from the application was to use the Magnetic and Electric Fields physics to add a Lumped Port. Currently the simulation I am running is an Electric Current Physics with a Terminal and Ground to inject current and two voltage probes to detect voltage difference (See picture attached). Is the only way to add an AC current through the Magnetic and Electric Field Physics? When adding that physics it requires me to put permeability which is not a material property I have at the moment. Is there not a way to add the AC Current through the Electrical Currents physics? My apologies if some of this is a bit repetitive, I felt I didn't give you a clear explanation of the project upfront.

I really appreciate the help

>Here's a 5.5 version. Howdy, Thank you for that. What I got from the application was to use the Magnetic and Electric Fields physics to add a Lumped Port. Currently the simulation I am running is an Electric Current Physics with a Terminal and Ground to inject current and two voltage probes to detect voltage difference (See picture attached). Is the only way to add an AC current through the Magnetic and Electric Field Physics? When adding that physics it requires me to put permeability which is not a material property I have at the moment. Is there not a way to add the AC Current through the Electrical Currents physics? My apologies if some of this is a bit repetitive, I felt I didn't give you a clear explanation of the project upfront. I really appreciate the help


Robert Koslover Certified Consultant

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Posted: 3 years ago 26.03.2021, 13:48 GMT-4
Updated: 3 years ago 26.03.2021, 13:51 GMT-4

If you are not using magnetic materials, you can usually just set the relative magnetic permeability = 1. In regard to other ways to specify AC ports or boundary conditions, I believe that several exist. What works best in one application may not work so well in another. I encourage you to experiment with the options available to you to see what works. Also, perhaps some others on this forum can offer other more specific suggestions and examples. Good luck.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
If you are not using magnetic materials, you can usually just set the relative magnetic permeability = 1. In regard to other ways to specify AC ports or boundary conditions, I believe that several exist. What works best in one application may not work so well in another. I encourage you to experiment with the options available to you to see what works. Also, perhaps some others on this forum can offer other more specific suggestions and examples. Good luck.

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