Need help interpreting stepper motor curve
Need help interpreting stepper motor curve
(OP)
Hello all,
A recently recieved a curve from a stepper motor manufacturer. It is torque (oz-in) vs. speed (rps). It also has power vs. rps on the same graph, represented by a dotted line. I thought power was torque (N-M) * Velocity(rad/s)? I do these calculations, and the power i calculate is way more than the power shown on their curve. Is it possible that the motor is limited somehow and is the power on this curve also the output power if this motor is used as a generator?
Thank You,
hmic21(M.E.)
A recently recieved a curve from a stepper motor manufacturer. It is torque (oz-in) vs. speed (rps). It also has power vs. rps on the same graph, represented by a dotted line. I thought power was torque (N-M) * Velocity(rad/s)? I do these calculations, and the power i calculate is way more than the power shown on their curve. Is it possible that the motor is limited somehow and is the power on this curve also the output power if this motor is used as a generator?
Thank You,
hmic21(M.E.)





RE: Need help interpreting stepper motor curve
One possibility for the discrepancy is the difference between the theoretically available torque at any speed (which occurs at a torque angle of 90 degrees) and the recommended maximum usable torque, which is typically about 50% of the maximum available, to provide a good safety margin for overcoming disturbances. It may be that the power curve reflects the recommended maximum usable torque, rather than the plotted available torque.
Curt
RE: Need help interpreting stepper motor curve
RE: Need help interpreting stepper motor curve
RE: Need help interpreting stepper motor curve
I have a hunch that the solid lines represent the obtainable torque when full stepping, while their computed power obtainable is representative of the more realistic micro stepping mode. It would be interesting to see the chart.
RE: Need help interpreting stepper motor curve
P(watts) = T (N-m)*rpm / 9.549 = T(N-m)*rps*2Pi
1 (Oz-in) = 7.062 E-3 (N-m)
The power produced by 1 Oz-in @ 1000 rpm
P=7.062E-3*1000/9.549 = 0.7396 Watts
RE: Need help interpreting stepper motor curve
Do you guys know how to post pictures on here, I would really like someone who knows this stuff to take a look at this curve.
HMIC21
RE: Need help interpreting stepper motor curve
If you want to post a picture you must have it at a link that has just the jpg. <sad I know> Then you put the link in here like this:
[img xxxlinkxxx]
RE: Need help interpreting stepper motor curve
http://www.geocities.com/xxzeus07xx/index.html
Thanks
RE: Need help interpreting stepper motor curve
Just as aolalde sez:
P(watts) = T (N-m)*rpm / 9.549 = T(N-m)*rps*2Pi
P = T x 0.00
Looks about what I'd expect.
RE: Need help interpreting stepper motor curve
Curt
RE: Need help interpreting stepper motor curve
My bet is that the plot was drawn in error. Probably a typo by the manufacturer.
The manufacturers that I deal with have stopped printing the "Power" plot on their charts. Frankly I never paid attention to that plot anyway. I suppose it does give a visual aid as to what speed the motor becomes constant power, which might be useful when scanning a whole sheet of these.