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Electromagnetic Waves simulation including also Electrical Circuit and Magnetic Fields physics

Posted Jun 13, 2024, 6:31 p.m. EDT Electromagnetics, Low-Frequency Electromagnetics, RF & Microwave Engineering Version 6.2 3 Replies

Mika Maaspuro
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Hi, my first effort simulating electromagnetic fields generated by an electric circuit. In this case a simple bandbass filter. I utilize three physics: Electromagnetic Waves, Electrical Circuit and Magnetic Fields. First I would like to do a frequency domain study. All went quite fine if all components (except the pcb and wiring) were lumped parts and included in Electromagnetic Waves physics. Changing the coil to a geometrical model and using also Magnetics Fields physics made it more difficult to solve. And what for I cannot define the components in the Electromagnetic Waves if I included Electrical Circuit physics (the capacitors in the circuit). My ultimate goal would be an electromagnetic simulation (both frequency and time) for a more complicated circuit including a power converter (a switch, a transformer, capacitors and pcb with wiring). The transformer and wires would be geometrical models and the rest could would be lumped parts. This first simple model I managed to solve in one frequency point (about 0.5-1 hours simulation time) but the simulation failed at the second point. 1) Is there errors in the model? 2) Maybe a different solver or changes in the solver configuration?

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3 Replies Last Post Jun 21, 2024, 12:07 p.m. EDT
Dennis Brown
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Posted: 5 months ago Jun 14, 2024, 8:51 a.m. EDT

In your simulation you have not created the internals for the leaded parts (the capacitors and the ferrite bead).
Your capacitors have to have all of the plates or the internal guts. This is not easy.

In any case I would suggest starting out with a 2D equivalent and work your way up to 3D. There is an example that should help you here

https://www.comsol.com/model/a-low-pass-and-band-pass-filter-using-lumped-elements-15675

In your simulation you have not created the internals for the leaded parts (the capacitors and the ferrite bead). Your capacitors have to have all of the plates or the internal guts. This is not easy. In any case I would suggest starting out with a 2D equivalent and work your way up to 3D. There is an example that should help you here https://www.comsol.com/model/a-low-pass-and-band-pass-filter-using-lumped-elements-15675
Mika Maaspuro
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Posted: 5 months ago Jun 20, 2024, 6:25 p.m. EDT

Thanks for the comments. I also asked from Consol Support. It looks like it's impossible to combine Electromagnetics Waves and Magnetic Field physics as both of them try to solve magnetic fields and it becomes hard for the solver. I had to keep most of the components lumped ones and definately I need 3D-model.

Thanks for the comments. I also asked from Consol Support. It looks like it's impossible to combine Electromagnetics Waves and Magnetic Field physics as both of them try to solve magnetic fields and it becomes hard for the solver. I had to keep most of the components lumped ones and definately I need 3D-model.
Dennis Brown
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Posted: 5 months ago Jun 21, 2024, 12:07 p.m. EDT

You can use either mf or emw module but if it low frequency probably better to use mf or similar related physics. In either case you can use electrical circuit interface.

Modeling the ferrite bead is not that difficult provided that you have complex permeability data for the ferrite itself. If this is to mimic an existing SMT version then you have your work cut out. You would need to ask the vendor for ferrite material data.

Why do you need to know details of the capacitors? Unless you are designing them it is a lot of work and the mesh setup is more difficult. You could just use a dielectric box within the outer pkg that has ends as PECs and figure out dielectric constant to get wanted capacitance. Even meshing a ceramic capacitor with interleaving plates is difficult due to aspect ratio of the problem.

You can use either mf or emw module but if it low frequency probably better to use mf or similar related physics. In either case you can use electrical circuit interface. Modeling the ferrite bead is not that difficult provided that you have complex permeability data for the ferrite itself. If this is to mimic an existing SMT version then you have your work cut out. You would need to ask the vendor for ferrite material data. Why do you need to know details of the capacitors? Unless you are designing them it is a lot of work and the mesh setup is more difficult. You could just use a dielectric box within the outer pkg that has ends as PECs and figure out dielectric constant to get wanted capacitance. Even meshing a ceramic capacitor with interleaving plates is difficult due to aspect ratio of the problem.

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