Motor time constant 7

[FeX32]

Hey guys,

I would like some opinions. Say I have an AC electric motor that has an inductance of 4.5mH and resistance of R= 1 ohm

What is the likelihood I will be able to obtain 200Hz accurate torque fluctuation in the form of a sinus wave? Will the motor drive play a role in the time constant? (disregard any inertia or mechanical time constants)

I'm looking for some mathematics beyond L/R to help my physical understanding.

Thanks.

Cheers,

 

[Skogsgurra]

That is more of a design question. How large you make the motor, how well it is cooled and such tings. And, of course, also a question of what the drive really can deliver voltage- and current-wise. Carrier frequency also plays a role, but if you are in the 8 kHz range or higher, you should be fine

The current/torque loop bandwidth is, as mentioned before, calculated without any regard to practical limitations. It is the "school" reality, so to say, while thermal limitations and actual performance is "real" reality. Yes, there's a difference. That's why I am trying to put together a text on the "Automation Engineer and the Reality".

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[FeX32]

Thanks again Gunnar.
Carrier frequency? Is that related to the PWM? This seems to have optimal current loop speed

http://www.kollmorgen.com/en-us/products/drives/servo/akd/

I couldn't find the carrier freq. though.

If you write a text, I'd for sure be interested

 

[FeX32]

I think I'm going to put this topic to bed soon. I believe I have a good confidence level now.
Thanks a bunch everyone!