[radicooldude]

So, If I have a stepper, like a powermax 2, and it lists:
5.17Volt 1.63Amp, 1.8*/step, 200steps/rev

And I have a stepper driver that says 48v, 6amp max, then will I be hurting the stepper running it at 48v? Or do I run the stepper at 5v? I don't understand the voltage part of steppers. Also, how do I know how many phases a stepper is? Say a 8 lead bipolar.
Can someone explain these things for me? Thanks -Zack

[pminmo]

The motor has a coil rating which is the resistance of the coil, and the maximum current the coil can (should) handle. Your motor at 1.63A will develop 5.17V accross it's winding steady state DC. You could run a 5V ish power supply and be ok, but it won't be fast or strong. To get higher performance out of the motor, it really needs to see higher instantious voltages when it steps, but without current limiting the motor would be destroyed. You hear the terms chopped, ballast resistor, current limiting those methods allow the motor to use a higher voltage power supply and limit the current to the maximim the motor can handle.

Your driver has some method to set the max current. Set that to 1.63A or closes setting and you can use power supplys up to the 48V.

http://www.geckodrive.com/photos/Step_motor_basics.pdf is a very good writeup on this.

[khootk]

I'm using 3V, 2.14A /phase bipolar stepper motor & drive with A3977, chip max rate: 2.5A, 35V.
What is your suggest for the apply voltage and current to the motor.
I had try to apply voltage 28VDC, current limit 0.6A (holding stage) accelerate current 1A ,
motor itself cause a knocking at each revolution. Try another setting 16VDC, Current dose the same as above,
but the knocking noise level reduce. What cause the knocking noise & how can I utilize the stepper motor?

[pminmo]

khootk,
You should be able to use the 28V no problem. Lots of things could cause your knocking, depends on how the 3977 is used.

[dwjbosman]

In the end it's not about the voltage and current but about power. The power (Watts) which is used by the motor is the voltage multiplied by the current (P=VI). In the end the power determines the heat which will build up inside the motor. To much heat and your motor will fail...

Now for the calculation:
Your motor has some internal resitance R, which is probably stated in the datasheet.

In the current limiting drivers, the current is maximized to the motor's allowable current. With ohms' law (V=I*R) you can fill in the current and resistance and you will find the maximum allowed voltage.

For another example see a our product where we use the A3977 to drive Vexta PK266 motors: BlueStep/BluePower