Перед началом работы настоятельно рекомендуем ознакомиться с правилами форума.

Setting eddy losses

chetank
Аватар пользователя chetank

I have Maxwell 2D transient model of a motor in which I wish to calculate eddy current losses in stator winding conductors due to rotation of permanent magnets of rotor.

I have set set eddy effects in excitation menu but not defined any current direction. Eddy current direction shall be along the surface of the conductor and not along the length of the conductor.

The results abotained without specifying anyurrent direction and just setting eddy effects are not practical. I'm plotting solid loss.

Is it required to assign current direction of solid conductor to calculate its eddy current loss due to magnets?

Note In this model, band has been assigned motion with rated rpm and no excitation of windings is given rather no windings are present. Only solid conductors in slot are present.

Klyavlin
Аватар пользователя Klyavlin

Hello. In your case, I think, you should combine all sections of conductors for 1 phase in winding (solid, Current =0A). It means no load, only extra loss. The right direction of eddy current for section will be +/- normal to workplane.  

chetank
Аватар пользователя chetank

Yes I have already tried that and got practically matching results also.

But in such winding current direction is always along positive or negative z axis. But actual eddy currents along the curved surface and not along the z axis .. Am I right? But still how did I get correct results? 

Klyavlin
Аватар пользователя Klyavlin

You can make shareable model and attach it. I'll see it. 

chetank
Аватар пользователя chetank

Sure I will attach it soon. But Maxwell manual does not mention about specifying a winding to the object whose eddy loss to be computed.

Another doubt, in transient 3D analysis I want to calculate eddy current losses in motor's bottom flange due to rotor magnet leakage flux. Is it sufficient to check set eddy loss in flange under excitation or something else to be done? Flange is stationary.

chetank
Аватар пользователя chetank

 

Well with reference to my thread regarding eddy currents in transient solution I am attaching model. The model is for ironless machine.

1. In the model, there are two 2D transient models one is solved with symetry other one is fully solved. In one, all conductors are assigned to a single winding and in second only excitations are applied. Both give same results and matched practically also. But current direction is along z axis and eddy currents in winding currents in along the conductor surface... I cound not understand this.

2. Second is 3D model in which motor flange eddy loss is to be estimated due to leakage flux of PMs. Kindly tell checking box for set eddy against the object is sufficient to estimate losses ? I did with winding for the flange also and got same result in both cases.

Your explanation will be helpful.

Thanks.

Klyavlin
Аватар пользователя Klyavlin

Цитата:
Is it sufficient to check set eddy loss in flange under excitation or something else to be done? F

Yes

Klyavlin
Аватар пользователя Klyavlin

About 2d task with symmetry. I checked it, and there is not any mistakes. J field in conductors is eddy and look as at the picture. The vectors are directed normal to the surface, not along conductors surface.

About 2d without symmetry. The magnet magnetization should be as in the task without symmtry. Also, try rotate magnets, not inner rotor. 

3D. Try to use dummy objects around disk. It is very useful for build acuracy mesh in gap.

 

chetank
Аватар пользователя chetank

Hi.. Thanks Friend.

But as per theory, the induced currents in conductors shall produce opposite magnetic field and working field (PM field) is almost radial in air gap through conductors. So, ultimately direction of induced current shall be along the surface and not shall along the axis of the conductor. ( to produce counter field)I mean, these eddy currents shall circulate along the surface and not along the cross section of the conductor.

Am I missing something?

Klyavlin
Аватар пользователя Klyavlin

The plane in which eddy currents are induced is always located so that the vector of magnetic induction that generates them is always directed along the normal to it.

https://en.wikipedia.org/wiki/Eddy_current#/media/File:Eddy_current_brake_diagram.svg

In other words, if you expect the currents to be in the plane of the wire, then the vector of the magnetic induction of the magnets must penetrate this plane in the direction through the screen

 

Добавить комментарий

Войдите или зарегистрируйтесь, чтобы отправлять комментарии
Приложить файл

Максимальный размер файла: 128 МБ.
Допустимые типы файлов: txt doc docx xls xlsx pdf rar zip 7zip tar.