Hi,
I am trying to calculate currents induced in individual conductors in an electric motor (similar to this forum post).
But I am getting a mismatch between the Component currents calculated by the CircuitsAndDynamics solver and the currents I calculate by integrating `current density e` over the conductor bodies.
The Component currents look somewhat reasonable and add up to the total current I put into the model:
The currents calculated by integration are different and oscillate wildy:
I have tried this on a simplified case with just a few conductors and no other parts of the motor and the currents calculated by both different methods were the same.
Are there maybe any convergence settings that need tweaking? Or is there something more fundamentally wrong with my model setup.
I have attached the case setup in the zip file. Any input would be much appreciated.
Difference between Circuit and MagnetoDynamics currents
Difference between Circuit and MagnetoDynamics currents
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- ac_loss_elmer.zip
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Re: Difference between Circuit and MagnetoDynamics currents
This is a diagram of the circuit:
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Re: Difference between Circuit and MagnetoDynamics currents
Hi
Wow, what a circuit! Do you have some tool for building it?
pdf2 is not the most stable time-integration scheme. Maybe you can try 1st order.
-Peter
Wow, what a circuit! Do you have some tool for building it?
pdf2 is not the most stable time-integration scheme. Maybe you can try 1st order.
-Peter
Re: Difference between Circuit and MagnetoDynamics currents
I have used elmer_circuitbuilder to create the circuit. It is fairly straightforward using that. Just requires modifying the circuits.definition file afterwards to put the time varying currents in.
Plotting the circuit was done using pydot, which uses graphviz as a backend. Again, that's pretty straightforward once the circuit has been created.
Well, that was an easy fix. The currents are matching after changing the timestepping order to 1. Thanks a lot.
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Re: Difference between Circuit and MagnetoDynamics currents
Hi, Maybe you can share the improved comparison as well. -Peter
Re: Difference between Circuit and MagnetoDynamics currents
Sure, it is a bit tricky to visualise, since there's so many lines and no visible difference anymore, but I gave it a shot:
Individual currents (Left: Circuit Components, Right: FEA surface integral): Sum of all currents:
Individual currents (Left: Circuit Components, Right: FEA surface integral): Sum of all currents:
Re: Difference between Circuit and MagnetoDynamics currents
Hi,
It looks that we are having the same problem
https://www.elmerfem.org/forum/viewtopic.php?t=8238
How do you excite your coils - voltage or current?
It looks that we are having the same problem
https://www.elmerfem.org/forum/viewtopic.php?t=8238
How do you excite your coils - voltage or current?
Re: Difference between Circuit and MagnetoDynamics currents
My coils are current excited. I haven't tried voltage excitation.
My problem was fixed by switching
Code: Select all
BDF Order
Re: Difference between Circuit and MagnetoDynamics currents
This does not make a difference in my case. Changing time-stepping schemes worked for cases with lower frequency, but this high-freq still has these oscillations. Making smaller timesteps seems to make things even words.