Motor modelling

[Kanu_01]

I have a motor of 44kW rating. I am choosing a typical data in SKM for my load(fan model) and motor model for TMS studies. And I could see an error of motor torque could be smaller than the load torque. What should I do to mitigate this error? I tried using different model, but still couldn’t mitigate the error.

 

[dpc]

Verify the load torque data is correct? If you are just using the "typical" library data in SKM, your results may not be that meaningful anyway. Especially for a non-NEMA rated motor.

 

[waross]

And I could see an error of motor torque could be smaller than the load torque.

Are you selecting the proper speed models?
Is this steady state or during starting?
You may have set a too short acceleration time.

 

[Gr8blu]

Motor torque performance (especially during transients such as acceleration) is carefully chosen against the required load torque for the process. There are multiple ways to change the shape of the motor's torque curve to better suit a specific load profile: the methods range from choosing a different material conductivity (i.e. rotor bar and/or ring) to modifying internal geometry (slot size/count, location and number of air ducts, radial air gap, etc.) to simply increasing the machine's steady-state power output (so that the per unit values for transient performance are based on a larger "base" number).

From the OP's description, it sounds like the "default" SKM design is a NEMA B, where the specific fan application (for whatever reason) needs something a bit more like a D.

The first step is to verify the actual fan load torque (curve) requirements. The second is to verify the motor torque performance.