Stepper Motor Max RPM

[Fish4Fun]

Fish4Fun submitted a new resource:

Stepper Motor Max RPM **Theory** - Stepper Motor Max RPM **Theory**

I dabble in CNC as a hobby. Like all physics based hobbies noobs frequently do not understand why their projects perform poorly and generally refuse to believe the answer is as simple as component matching. A constantly recurring scenario is poor stepper motor performance....Stepper motors are typically marketed, sold and purchased almost exclusively on "Holding Torque", a specification that is all but meaningless in determining the performance of any given stepper motor in any particular...

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[Harald Kapp]

Wouldn't this make a great ressource?

 

[Fish4Fun]

Thanks Harald!

(Selfishly) That is why I posted it here....so I could just send people links to it w/o having to re-write it every time it comes up ;-) I am, of course, ever hopeful that others might contribute to it, but even if they don't it pretty much covers the most common recurring problems I encounter with cnc-noobs who don't understand why their machines perform so poorly....

Fish

 

[Harald Kapp]

I thought about an entry in the ressource section...

 

[Ian]

I can convert this to appear in the resources tab at the top if you'd like @Fish4Fun? I agree that it would be a great resource!

 

[Fish4Fun]

Hey Ian!

Of course. As I mentioned I really posted here so that I could direct people to it w/o having to re-write it/C&P it...making it a resource just makes it easier to find ;-)

Thanks!

Fish

 

[Ian]

Brilliant! I've converted this to a resource now, and the original thread is now the linked discussion topic .

 

[Colin Mitchell]

This is the most important part of the article:

So the Theoretical maximum RPM for the Stepper using a 36V Power Supply AND reaching the rated current of 3.5A is only 580 RPM.....I am NOT saying a 36V supply will not spin one of these motors faster than 580RPM, but the torque will drop-off very rapidly above the 580RPM point. Same math for a 48V supply yields ~770RPM, and a 60V supply yields 975RPM while a 24V supply only yields 362RPM.

At least it gives some idea of the RPM to expect, even though stepper motors are generally used to give an accurate position through the number of steps delivered to the motor.
In most cases it is "step-counting" as you know the number of steps per rotation.

 

[hevans1944]

And this is why PWM supplies for stepper motors are the preferred drive paradigm. If the winding insulation can stand for it, it is not uncommon for PWM supplies to deliver pulses with amplitudes ten to a hundred times greater than the motor's rated voltage. So, a low-voltage (2 V), low resistance stepper motor can be driven with 200 V constant-current pulses providing high current without overheating.

The enclosed application note from STMicroelectronics helps to explain why.