How to decide run current and hold current in stepper motor

[KevinQ]

I am programming a motor controller where I have to specify the run current (coil peak current) and hold current (coil hold current) of the motors. The motor I used is a bipolar stepper motor, with a whopping 1.86Kg/cm of stall torque at 1.5Amp current (0.75A per winding) at 1.8 degree stepping angle.However, the table in the specification makes me confused: It lists a different current for a different torque.Here is a link to that motor controller http://www.nex-robotics.com/products...per-motor.html.How could I determine run current and hold current from this specification?

[jwatte]

That table says something like:

"If you want this torque, then you need to supply at least this many volts, and that means the motor will draw this many amps."

So, it's up to you. Do you want to run the motor full throttle? Then provide at least 6V, and limit amps to 1.5. (This divides out with PWM, too, so 6V, 3A, at 50 % duty cycle may give similar results.)
Generally, for a driver, though, you want to provide a lot more voltage, and instead limit current, using a chopping driver. And, reading that data sheet, any "max current" setting of 1.5A or lower, per winding, should be safe. Higher would probably be possible, but wouldn't be recommended for any long durations or high duty cycles.