[extreme]

Hello everyone,
I have this question: If run a stepper on higher revs and increase voltage, will the torque drop or stay the same as in lower rpm ? What is the practical rpm range for a stepper motor (with rised voltage). I know the more voltage the bigger this range is but there is some limit i think.


Thanks,
Robert

[mcmmach]

This web site should give you an idea of the speed vs torque.

http://www.velmex.com/motor_torque.html

Also the step size has a big effect on torque, most motor torques are rated at half step, if you go to 1/8 or 1/16 or more the torque drops off rapidly even at low speeds.

[extreme]

Mcmmach, thanks for reply.
I allready know that torque more at bigger rpm. I think all (or most) of factory tests are at nominal voltage. If I connect a 2 volt stepper to 20 volt controller (pwm or resistors), how much would the curve change?


Thanks,
Robert

[mcmmach]

Hi Robert,
The only graphs I have seen compared a 36 volt power supply and a 72 volt.
Using a nema 34 size motor the 36 volt setup had 50 oz in of torque at 1000 rpm.
The 72 volt setup had 80 oz in at 1000 rpm.
Both setups were wired in parallel and pulling @10 amps
If I remember correctly you can drive a motor at 25 times the rated voltage maximum, any more and the motor will overheat.
Dean

[mcmmach]

An addition to my previous post;
Both setups started out at 225 oz in at zero rpm, the higher voltage only helped at the higher rpm's
Dean

[ger21]

A general rule of thumb, is if you have useable torque at a given rpm, doubling the voltage will double the useable speed.

There is no practical range, because there are too many possible combinations of motors and drives.

Ususally your voltage will be limited by the drives your using, but if you have steppers with a very low voltage rating, too high a voltage can cause excessive heating.

[extreme]

Thats exactly what I needed to know !

Thanks guys.