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nonlinear BH curve leads to disconvergence problem

Posted 8 mar 2018, 04:38 GMT-5 Electromagnetics, Low-Frequency Electromagnetics Version 5.2a 2 Replies

Zhi Xu
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Hi everyone:

im modelling interior PMSM in comsol 5.2a for my work at this moment. Firstly i chose soft iron as the material for my stator and rotor and the study solver went on with no problem (both stationary study and transient study). Then when i checked the BH curve of soft iron and realized it isnt as close as the BH stats published by the factory. The 'real' BH curve is much more steeper than the BH curve of soft iron especially in the beginning part. Once i modified the BH curve my study just cannot converge. Two solution i found and gave a shot: a) i used step by step method to ramp up the source (current+PM), but it failed no matter how soft the source is being ramped up. This method is given in details in comsol forum as well. b) i used silicon steel to replace the soft iron since the BH curve for silicon steel is similar to the real BH curve. Then seems like the problem was solved but one thing i noticed is that the transient study goes really slowly.

SO i was wondering how you guys deal with this material nonlinearity and any tips to speed up the transient study? Thank you!

Best Wishes Xu Zhi

2 Replies Last Post 9 mar 2018, 09:33 GMT-5
Zhi Xu
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Posted: 7 years ago 8 mar 2018, 06:50 GMT-5
Updated: 7 years ago 11 mar 2018, 07:01 GMT-4

i think its a nonlinear-led disconvergence problem and its heavily-related to the meshing and bh curve nonlinearity. But at this moment i dont really know how to refine my mesh cause my model is rather complicated and a fine meshing could be extremly time-consuming. Anybody help?

i think its a nonlinear-led disconvergence problem and its heavily-related to the meshing and bh curve nonlinearity. But at this moment i dont really know how to refine my mesh cause my model is rather complicated and a fine meshing could be extremly time-consuming. Anybody help?
Yara Soares COMSOL Employee

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Posted: 7 years ago 9 mar 2018, 09:33 GMT-5

Dear Zhi Xu,

I would advise you to send in your question to support@comsol.com for a swifter response.

Kind Regards,

Yara Soares

COMSOL BV | Röntgenlaan 37 | 2719 DX Zoetermeer Phone: +31 (0)79 363 4230 | Fax: +31 (0)79 361 4212

www.comsol.nl | yara.soares@comsol.com

Dear Zhi Xu, I would advise you to send in your question to support@comsol.com for a swifter response. Kind Regards, Yara Soares -------------------------------------------------------------------------- COMSOL BV | Röntgenlaan 37 | 2719 DX Zoetermeer Phone: +31 (0)79 363 4230 | Fax: +31 (0)79 361 4212 www.comsol.nl | yara.soares@comsol.com ----------------------------------------------------------------------

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