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inductance calculation by magnetic energy density
Posted Feb 7, 2016, 7:49 a.m. EST Low-Frequency Electromagnetics Version 5.2 1 Reply
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Hi ! i noticed that inductance can be calculated via formula Wmp=0.5*L*I^2 . So imagine there is one coil with known current flowing in it, then the next step is to calculate the magnetic energy Wmp. This can be achieved from integrating the magnetic energy density over the surface. My question is: shall i choose 'all domains' as my surface? If so, why?
Thanks !
Thanks !
1 Reply Last Post Feb 9, 2016, 3:07 p.m. EST
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Posted:
9 years ago
Hi Zhi,
In 3D geometry, if you have a closed loop conductor carrying current, and magnetic material around it, then most of the magnetic energy is stored in the magnetic material. However, if you have just a coil in air, the energy will be distributed to some distance away. You would have to make the air volume sufficient large or use the Infinite Element Domains to correctly compute the inductance. In any case, it is important that you integrate the energy over the entire volume (system) to compute the inductance.
You might find this power inductor example helpful:
www.comsol.com/model/modeling-of-a-3d-inductor-10299
However, if the coil is open ended, you will never get the correct inductance value as described here:
www.comsol.com/blogs/computing-the-inductance-of-a-wire/
Additional blog that might be interesting:
www.comsol.com/blogs/model-cables-and-transmission-lines-in-comsol-multiphysics/
Best Regards,
Nirmal
In 3D geometry, if you have a closed loop conductor carrying current, and magnetic material around it, then most of the magnetic energy is stored in the magnetic material. However, if you have just a coil in air, the energy will be distributed to some distance away. You would have to make the air volume sufficient large or use the Infinite Element Domains to correctly compute the inductance. In any case, it is important that you integrate the energy over the entire volume (system) to compute the inductance.
You might find this power inductor example helpful:
www.comsol.com/model/modeling-of-a-3d-inductor-10299
However, if the coil is open ended, you will never get the correct inductance value as described here:
www.comsol.com/blogs/computing-the-inductance-of-a-wire/
Additional blog that might be interesting:
www.comsol.com/blogs/model-cables-and-transmission-lines-in-comsol-multiphysics/
Best Regards,
Nirmal