View Full Version : How can I find fast stepper motor / controller combo?

23-07-2013, 09:37 AM
I'd like to make my pick and place faster. The machine speed is acceleration limited, i. e. dynamic torque. But that is not generally specified. My experiments show that static torque is quite different thing: I have tried four motor types. The low torque nema17s were the slowest, but the medium torque nema17s are faster than both high torque nema23s. There was no big difference between the different nema23s, but the lower torque was faster. All with the same controller.

So, I found no correlation between the torque spec and real life speed. I guess I don't understand what is going on. Maybe maximum attainable speed is a finction of some controller and motor parameters that I don't know how to calculate or maybe the speed really depends on something that the motor manufacturers don't tell us. But I'd like to stop my blind experiments and learn something. Any comments or advice?

23-07-2013, 11:16 AM
Torque is proportional to current, but dynamic torque and thus acceleration & speed is controlled by how quickly that current builds in the windings and that is controlled by the winding inductance and the voltage to the driver. These parameters dictate the corner speed of the motor, below which you'll get close to the static torque and above which torque drops off rapidly.

So low inductance motors and high voltage drivers.

23-07-2013, 12:32 PM
This makes much sense, and re-reading the datasheets, matches my experiences: Lower inductance, faster speed (with teh same driver and power supply). Thank you! Now I know what parameter to look if I want to make the machine even faster.