# Torque Vs Speed curve of the Stepper motor

• posted

Hi,

Does torque vs speed curve tell anything about the acceleration and deceleration characteristics of a stepper motor?

Farah

• posted

I know little of stepper motors, but if you tell me the torque and moment of inertia, I can tell you the angular acceleration. (It's just like F=m*a)

George H.

• posted

The problem is that we want to replace the old stepper motor with a new stepper motor and we are trying to build an argument that new can replace the old one because their speed vs torque curves are same. Is this the right way to prove?

We do not have any information about the acceleration and deceleration of the old stepper motor.

if we compare the speed vs torque curves and if they turned out to be same then would it be okay to conclude that the acceleration and deceleration of the two motors will be same?

• posted

Right that sounds reasonable, but as I said, I don't know much about steppers. Do they have the same number of poles? (same number of steps to make one revolution.) What's it for? Are you buying a few or hundreds? Maybe someone (more knowledgeable) will step in.

George H.

• posted

Yes, they have the same number of poles and same number of steps to make one revolution.

• posted

Hi, Can anyone give me some suggestion on how to calculate the acceleration and deceleration using torque vs speed curve?

• posted

Acceleration is proportional to torque. The constant of proportionality depends on the flywheel-like inertia constants of the moving parts being driven. Friction, too, is of concern, and makes a counter-torque.

• posted

It is a little more complicated than that when dealing with steppers and drivers for steppers. But there's lots of info on the web.

I'd start by finding the specifications of the one you have then finding something close, things like step angle (anywhere from 90 degrees per step to 0.72 degrees per step depending on the number of poles in the motor) shaft size, torque, holding torque, voltage, current, (step angle, voltage and current should get you close enough, and of course shaft diameter and length)

AND there's the type of motor - unipolar or bipolar drive.

There's some standardization of case sizes too between different manufacturers, so you may be looking for one. National Electrical Manufacturers Association, assigns numbers for standardized physical dimensions of the motors.

I ain't no expert either, but I've done a little tinkering with them.

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