Discussion Forum

Hello,

I am trying to simulate an 4pole (q=3) asynchronous machine with the .rmm physics module in 2D with COMSOL 4.1.
So far I am able to excitate the coils with a Voltage through the "Electric Circuits"- Physics interface to create the rotating field in the stator.

Now I want to let the rotor rotate. Doing this with the prescribed velocity works fine. Composed parts and the identity pairs are being considered.
The problem is, that the rotor slots are not connected to each other in 2D, so no current is able to flow through the rotor and no torque is being excited.

I tried to create that short-circuit via a "multi coil domain" and chose the excitaion as "circuit".
Put a very big resistor between the upper node of the "External I vs U" and the voltage source, which is set to 0V.

Simulating this, brings no error. BUT the electric conductivity within the coil domain is 0. So no current can flow in the rotor. The "multi coil domain" seems to be responsible for this, because it overwrites the materials electrical conductivity.

After that I tried to use a "Single coil domain" for the rotor slots, because it doesn't overwrite the conductivity.
Simulating brings the following error:

Circular variable dependency detected.
- Variable: mod1.cir.UvsI1_v
- Geometry: 1
- Domain: 90

What does this error mean exactly and how can I solve it?


At the moment I have no other idea to tell COMSOL that the rotor slots are connected to each other... Do you?

I want to let the rotor rotate through an equation and read that would be possible with "ODE and DEAs"-physics. Do you have any advices for this?

I would be really happy about some help.


Thanks in advance.