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Topic: What voltage for stepper motors (Read 145 times) previous topic - next topic

Hey everyone,

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.

I've seen various sites on the internet using 12 V and 24 V power supplies, how does one determine what voltage to use?

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. 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.

Robin2

I think the Thread stepper motor basics will answer your question.

...R

Thanks Robin2, have read the entire post that you provided in your link and am now much more knowledgeable and have the answers I was looking for to progress with my endeavors.

By the way, I though it was an excellent beginners guide and certainly met my requirements (I wouldn't say I am an absolute beginner, while I've only been experimenting with Arduinos and electronics for 2 weeks as a hobby, I would say I was at an intermediate level) and the information you provided allows me to fill in gaps in my understanding and progress to the next stages. Really appreciate you having written the article and in pointing me in its direction.

Simon

Robin2

Thank you for your kind words.

...R

MarkT

Hey everyone,

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.

Quote
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
larger.

Quote
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
during rapids.
Quote
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).
[ I won't respond to messages, use the forum please ]

polymorph

Careful, MarkT, if someone is using an L298, all that is out the window.

What you said is absolutely correct if and only if you are using a chopper driver.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - tinyurl.com/q7uqnvn
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

MarkT

A 1.7A NEMA17 is the lowest-impedance stepper in its class, a L298 would be an abysmal choice,
you'd waste more power in the drivers than the motor got.  Chopper drive only for that kind of
motor...
[ I won't respond to messages, use the forum please ]

polymorph

I agree, but it should not remain unsaid.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - tinyurl.com/q7uqnvn
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

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