I have a vexing question, well to me at least. What voltage power supply should one use to power stepper motors? I have a NEMA 17 stepper and it's specifications doesn't even list its voltage. Researching the NEMA 17 online from its manufacturer reveals a specified voltage of 3.4 V.
Bipolar steppers don't have a voltage rating, they have a current rating since they are
current controlled. At speed the voltage is mainly backEMF anyway, the IR voltage is
pretty much irrelevant.
I've seen various sites on the internet using 12 V and 24 V power supplies, how does one determine what voltage to use?
Larger voltages allow the motor to turn faster since larger backEMFs can be overcome. And
this allows the motor to run at higher mechanical powers since the speed and torque will be
I understand that, for example, the max. current draw on my NEMA 17 is 1.7 Amp so of course, the power supply must be capable of continuously supplying more than this.
Not at all, in fact the supply will typically provide much less than this. The motor current and supply
current are not the same. The whole principle of chopper driver circuit is that of a buck-converter.
Only at maximum motor speed will the supply current approach the motor current. For a typical
application such as a CNC machine this is only achieved for a small proportion of the time
And a power rating that exceeds the current draw times the voltage, but it's this voltage I'm unsure how to determine.
Any assistance would be appreciated.
Unfortunately trial and error is the only way since backEMF/speed figures are rarely supplied
for stepper motors in datasheets and the maximum usable torque is a complex function of
drive voltage, mechanical load, microstepping settings and resonances...
Top end CNC machines might use 80V or 120V, simple 3D printer more likely to have 24V.
If you don't need much speed you might have been better off with a unipolar motor which is
cheaper to drive (but slow).