Hi,

I want built a system on simulink where I've an a assynchronous motor with squirrel cage rotor driving an a assynchronous generator to test if my the control system of the generator is working. So my system is something like the image bellow. My problem is that I dont know if the block corresponding to the motor is really working like a motor and not like a generator. And the same doubt applies to the generator block.

I read on simulink help that when Tm is <0 the block works like a generator and when it's positive works like a motor so I've used two fcn blocks to give different signals to the two machines. Can this be done this way? How can I confirm how the two machines blocks are operating? The conection to grid of the two machines (Vn=220V, fn=60Hz) makes sense?

 

I couldn't fully comprehend what you wanted to ask so if I miss out on something, feel free to point out.

The Tm < 0 condition looks fairly obvious as it probably represents load torque on the machine and should indeed be positive for it to function as a motor. If you indeed want to verify it, you could probably apply a positive value to the input and check the generated torque on a scope. The motor would try to equalize the load torque with the generated torque - a process during which it will draw power.

You could check the state in which the machine is operating by checking whether power is being supplied (+ve/generator mode) or drawn (-ve/motor mode).

The machine speed is determined by the machine Inertia J (or inertia constant H for the pu machine) and by the difference between the applied mechanical torque Tm and the internal electromagnetic torque Te. The sign convention for the mechanical torque is: when the speed is positive, a positive torque signal indicates motor mode and a negative signal indicates generator mode.

I lifted this straight from the docs and it is probably what you are referring to. I don't have MATLAB on my PC at the moment, so I'm afraid I can't check out the machine model.

Hope this is of some help.