Discussion Forum

Posted: 1 decade ago Dec 6, 2012, 5:17 a.m. EST

Hello, The Magnetic and Electric fields physics does not support Time-dependent studies, only Stationary and Frequency. You can see it in the Time Dependent step (the yellow sign near the physics's name in the table). Depending on what you want to do, you need to use another physics, for example Electric Currents. Note that your model as it is now cannot be solved with a Magnetic interface since it does not respect current conservation (current is "created" on one boundary and "destroyed" on another). -- Andrea Ferrario Electromagnetics Group COMSOL AB

Posted: 1 decade ago Dec 6, 2012, 10:43 a.m. EST

great answer. thank you very much. I don't know why there is no note about incompatibility of MEF with time dependent solver in manuals. Also thanks for your note. but one question rises now if magnetic and electric interface doesn't work for this, how can we see magnetic field while we apply voltage to the model. another question is " Is it OK to use parametric solver with the time as variable instead of time dependent one with magnetic and electric solver?" Regards,

Posted: 1 decade ago Dec 6, 2012, 11:30 a.m. EST

Hi there is in the doc if you get to the right page ;), but you should also check the solver proposed when you enter the physics, there you see which are "set-up" by default, and also by looking to the equations , if you have d/dt 's your time response will work if you have w omega's, the frequency response too, but if none appear, when you switch your selected solvers then no luck. Also ACDC is assuming instantaneous time response on the magnet fields, else you are in wave propagation mode = RF -- Good luck Ivar

Posted: 1 decade ago Dec 6, 2012, 2:41 p.m. EST

thanks for the answer. the final question from is this: is there anyway to apply voltage and see magnetic field while using time dependent solver? Thanks for support

Posted: 1 decade ago Dec 6, 2012, 3:40 p.m. EST

Hi check http://www.comsol.eu/community/forums/general/thread/33429/#p91817 and see if that can inspire you ;) -- Good luck Ivar

Posted: 1 decade ago Dec 7, 2012, 10:55 a.m. EST

what a comprehensive answer. thanks. you mentioned " you run time solving in EC and a parametric sweep in MF based on the current domain mapping" . would you mention the details or refer to a document about this coupling? Regards,

Posted: 1 decade ago Dec 7, 2012, 11:55 a.m. EST

Hi if you are studying a steady state sinus, it often far easier and quicker to use the frequency domain solver than a true transient, transient behaviour and sustained sinus excitation is not fully the same, because you have all the transient effects from your inperfect BC's in the time solver -- Good luck Ivar

Posted: 1 decade ago Dec 23, 2012, 7:09 p.m. EST

Hi fellas I finally could have time-dependent analysis with magnetic field solution. however it has a serious problem. I used MF solver with multi turn coil for each phase of my machine. the problem is working for just a single phase and when I enable the boundary for the second and/or third phase, the solver doesn't work. I tried many modification but no progress. I would appreciate if you would help me. the file is attached (the solution is removed because of the large size: 800MB) Regards,

Attachments:

• IM -magnetic field final - all excited - Copy (3).mph

Posted: 1 decade ago Jan 28, 2013, 3:42 p.m. EST

Hi have you got your model running ? At least you could reduce the overall air size to some diam 0.4 ad somewhat longer than you imported model, then add some 4 cm of infinite elements and set them up for cylindrical coordinates. But I'm not sure what you expect to see ? then you define the ima,b,c over all the domains, but they have some sense only locally, I would rather use the formula directly in the multi-Turn Coil BCs Anyhow for continuous AC you should use the frequency sweep mode at a fixed frequency of 60 Hz and then give the amplitudes as complex values (physors) for the phase instead of the wv1,2,3(t) approach. The time domain is only useful for a transient turn on, and in MF you do not get any ringing as the 2nd time derivative physics is ignored -- Good luck Ivar

Posted: 1 decade ago Feb 3, 2013, 5:46 p.m. EST

[QUOTE] Hi have you got your model running ? At least you could reduce the overall air size to some diam 0.4 ad somewhat longer than you imported model, then add some 4 cm of infinite elements and set them up for cylindrical coordinates. But I'm not sure what you expect to see ? then you define the ima,b,c over all the domains, but they have some sense only locally, I would rather use the formula directly in the multi-Turn Coil BCs Anyhow for continuous AC you should use the frequency sweep mode at a fixed frequency of 60 Hz and then give the amplitudes as complex values (physors) for the phase instead of the wv1,2,3(t) approach. The time domain is only useful for a transient turn on, and in MF you do not get any ringing as the 2nd time derivative physics is ignored -- Good luck Ivar [/QUOTE] thanks. I think I have to give up using time dependent analysis with this model. But the problem is phase shift. How can I consider Ib=120

Posted: 1 decade ago Feb 4, 2013, 1:14 a.m. EST

Hi the phasor approach (complex amplitudes), should work check the the doc -- Good luck Ivar