The Vidar-magnet motor MK2

[hartiberlin]

Forgive my ignorance, but would the motor just stop about the position in the below image?

If you would attach a flywheel to the rotor axis these angles, where there is
not much positive torque could be overcome, if the integral over the torque
over a complete 360 degrees cycle is still positive !
Then we would get a selfrunning motor.

If the integral of the torque over the complete cycle adds up to zero, then it would not work.

Regards, Stefan.

[Low-Q]

I have done some modifications to the motor by using three iron poles instead of two. I have also added a steel can to the outer magnets. In addition, there is now fully magnet on the outer magnets - no iron parts attached to them. See the picture for details.
I have now measured an average of 9 Nm in 360degrees. All measurements had a torque in the same direction (?!).

So I was thinking: Isn't it more correct to use the "Area" instead of "Contur", tool and mark the rotating parts alone to measure torque in the rotating iron parts - as all the magnets are fixed as stators?
If I do that, the torque during 360 degrees are not so promising...

Br.

Vidar

[hartiberlin]

Hi Vidar,
yes the 3 single rotors must be measured alone and added up.

I think the contur line will give the same as the Area tool.
it only depends on the meshes that are next to the rotors inside the airgap,
there are ocurring the forces.
So put a "trapez-circle" line inside the airgap around each rotor and then measure the torque
from stress tensor for each rotor and add this up for each rotor angle.
If you know how to use LUA scripts, you could do this in 1 degrees rotor angle intervals
and then get every sum of the rotor torques and put in into Excel or Calc
spreadsheet from OpenOffice and plot a torque versus rotor angle graph.
Then are there more positive rotor torques more than negative rotor torques
values ?
Add up their areas and you can see, if it adds up to zero or
to a positive or negative value.
If it is zero then it will not work, if it is unequal to zero, then the motor will run
either clockwise or counterclockwise.

Regards, Stefan.

[Jdo300]

Hi Vidar,

I have used FEMME extensively and have written script files that will auto-rotate and take the torque measurements. If you attach that latest FEMME file, I'll be happy to run the simulation for you and generate a torque plot.

God Bless,
Jason O

[hartiberlin]

yes, Jason,
if you could please do this, this would be great,
as I don?t have time in this moment to play with it and
I would need to do it all manually, cause I don?t know LUA script language yet.
Many thanks in advance.

Regards, Stefan.