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Axial flux permanent magnet generator

Hi Dr. Ivar/All,

Iam trying to simulate the axial flux permanent magnet generator with two rotor and a coreless stator sandwiched between two rotor.

Permanent Magnets are attached on inner surface of the rotor in such a way that magnets on two rotor are in N-S orientation.

I used the following boundary condition for the different domain under rotating machinary physics(rmm)
- For PM i used the constitutive relation remnant flux density from the Amperes Law
- For two rotor i used the BH realtionship
- I used the multi turn coil domain to model the coil
-used the prescribed rotational velocity for the rotation fo the rotor
-used continuity

Apart this i used the free tetrahedral meshing .

I tried to simulate taking reference from the generator model in Comsol model library but still not getting the desired flux and the voltage.

I really need your suggestion regarding this matter.I tried to find out the discussion regarding the axial flux permanent magnet generator in the discussion forum but none of them are answered. I am stucked at this point please help me out .

I have attached the model by clearing all the mesh and solution for making it appropriate for uploading.

Thank you
Aruna



8 Replies Last Post May 27, 2014, 4:00 AM EDT
Posted: 5 years ago Dec 7, 2012, 2:55 AM EST
Hi

check the 2D generator and the realted model in the model library, see how the "rotating machinery is set up in 2D w.r.t unions and identity pairs and continuation.

The way you have defined your model you have fixed it, nothing can rotate.

I'm afraid your "air" volume is a bit small it will influence too much the fierld lines and give deviation to the results, in my opinion.

Finally I would make a "hole" in the middle of your coil cylinder and make these into toruses, <s you have a singularity on the axis there, not sure how the multi turn coil domain behaves on that topology.

Another point: sharp edges, its often worth to smooth sharp edges with fillets in ACDC (it's tedious to define the geometry and increases the mesh size drastically) but it increases the precision of your force results. But ignore this last remark so long your model is not operational, take one step at the time

--
Good luck
Ivar
Hi check the 2D generator and the realted model in the model library, see how the "rotating machinery is set up in 2D w.r.t unions and identity pairs and continuation. The way you have defined your model you have fixed it, nothing can rotate. I'm afraid your "air" volume is a bit small it will influence too much the fierld lines and give deviation to the results, in my opinion. Finally I would make a "hole" in the middle of your coil cylinder and make these into toruses,

Posted: 5 years ago Dec 19, 2012, 12:29 PM EST
Hi Dr. Ivar,

I don't understand what you say "The way you have defined your model you have fixed it, nothing can rotate".Please let me know what I can do to improve it.
Thank you.

Hi Dr. Ivar, I don't understand what you say "The way you have defined your model you have fixed it, nothing can rotate".Please let me know what I can do to improve it. Thank you.

Posted: 5 years ago Dec 19, 2012, 2:47 PM EST
Hi

if you use "union" mode your boundaries are superposed and COMSOL assumes continuity in a way the domains cannot move, one w.r.t the other. Check the model in the model library in 2D.

You need to use geometry assembly mode and combine the other objects with specific "unions".
It's rather well explained in the 2D model library model, so its similar in 3D

--
Good luck
Ivar
Hi if you use "union" mode your boundaries are superposed and COMSOL assumes continuity in a way the domains cannot move, one w.r.t the other. Check the model in the model library in 2D. You need to use geometry assembly mode and combine the other objects with specific "unions". It's rather well explained in the 2D model library model, so its similar in 3D -- Good luck Ivar

Posted: 5 years ago Dec 20, 2012, 11:14 AM EST

Thank you Dr.Ivar.
Thank you Dr.Ivar.

Posted: 5 years ago Dec 29, 2012, 2:45 PM EST
Hi Dr. Ivar/All,

Thanks for the reply.

I haven't used the union mode in my model which can superimpose boundary and restrict the rotation of model as per your suggestion. I am wondering that what can be other factor that can affect the rotation.

I am using rpm (speed) for rotation of the rotor same as 2D model of generator in the model library. Please let me know what could be other alternative way in COMSOL for the rotation.

Thank you.
Aruna
Hi Dr. Ivar/All, Thanks for the reply. I haven't used the union mode in my model which can superimpose boundary and restrict the rotation of model as per your suggestion. I am wondering that what can be other factor that can affect the rotation. I am using rpm (speed) for rotation of the rotor same as 2D model of generator in the model library. Please let me know what could be other alternative way in COMSOL for the rotation. Thank you. Aruna

Posted: 5 years ago Feb 14, 2013, 9:40 PM EST
Hi ,

Any suggestion please?

Thank you.

Aruna
Hi , Any suggestion please? Thank you. Aruna

Posted: 5 years ago Feb 20, 2013, 2:51 AM EST
Hi

first to simplify the "assembly mode" group by explicit geometry union the elements that are fixed, respectively mobile
then you need to check the example of rotary models in the model library, you need to cut the air gap by a cylinder (surrounding all the to define the "region" that rotates) and define assembly "continuity" over these "identity" pairs

--
Good luck
Ivar
Hi first to simplify the "assembly mode" group by explicit geometry union the elements that are fixed, respectively mobile then you need to check the example of rotary models in the model library, you need to cut the air gap by a cylinder (surrounding all the to define the "region" that rotates) and define assembly "continuity" over these "identity" pairs -- Good luck Ivar

Sahas Bikram Shah
Posted: 3 years ago May 27, 2014, 4:00 AM EDT

Hi ,

Any suggestion please?

Thank you.

Aruna

Hello. Good morning/good afternoon. I am also modelling axial flux machine like you have and stuck in the same problem like yours. How did you solve the problem of air gap and rotation? I tried first simply with creating an air gap and assembling with rotor and stator and using identity pair. But it gives problem in meshing. Did you cut the air gap with cylinder or something else? Since there are limited examples of axial flux machine in COMSOL your help or suggestion would mean a lot. Thanks.
[QUOTE] Hi , Any suggestion please? Thank you. Aruna [/QUOTE] Hello. Good morning/good afternoon. I am also modelling axial flux machine like you have and stuck in the same problem like yours. How did you solve the problem of air gap and rotation? I tried first simply with creating an air gap and assembling with rotor and stator and using identity pair. But it gives problem in meshing. Did you cut the air gap with cylinder or something else? Since there are limited examples of axial flux machine in COMSOL your help or suggestion would mean a lot. Thanks.

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