Discussion Forum

I am not sure how you can have a rotating machine with permanent magnets at the stator and no winding at the rotor... Or maybe I misunderstood your description of the system.

COMSOL allows you calculate the forces and torque on components when you set up the problem. Add a "force calculation" in the physics (Magnetic Fields) tree and select the components on which you need the forces/torque calculated. The results are available as global variables and displayed during post-processing (Derived Values).

For forces on iron, the method used should be based on virtual work. If you want to implement the torque calculation yourself, you can integrate a function based on Maxwell's tensor over a section of the air gap. You should be able to find plenty of papers describing how to do it.

Hope it helps.
Best,
Philippe

It has a coil, but for now, i haven't connected it to anything yet so no current.
for now i just need to know, having the speed rotation and the magnetic flux the torque the rotor is under.

Thanks for the tip I'll give it a try.

The following Magnetic Gear example shows how to do the torque calculation on two rotors/stator. Hope this will be useful.
www.comsol.com/model/magnetic-gear-in-2d-14583

Nirmal Paudel
--------------------------
COMSOL Employee
USA

Hi,

I am getting the following error:
Log of negative
Function: log
Failed to evaluate variable
Variable: mod1.St, Defined as: ((mod1.p>=mod1.pea)*((cs-mod1.c)*(log((mod1.p/mod1.pea))*(exp(((-Ea)/(Rg*mod1.T)))*ka))))
Failed to evaluate expression
Expression: d((2*mod1.St*test(mod1.c)*pi*r)*(dvol),{test0})

Do you know how to fix this problem?

Thanks in advance for the comments

We encourage you to post your questions on the related thread. Or create the new thread if needed.

Nirmal Paudel
--------------------------
COMSOL Employee
USA