Author Topic: Power supply for Nema 23 Stepper ? (Read 18433 times)

Buell · « **on:** November 10, 2018, 08:02:27 AM »

Hi all, Im trying to work out which power supply to Buy for my Build I have a Nema 23 rated at 2.8amps. Now i may Need to get a bigger one if its not powerful enough.. with that in mind I may go to the 4amp version.

So im really confused about the whole electronics rating etc. So thought it would be simple...the motor so Im lead to believe is 12v dc a little bit like my car battery and all components within the Auto vehicle. with that in mind my head says look for a 12v 4amp supply obviously 240v as i live in uk. simple !

So i get the 220v-110 supply power description but then it gets very weird FOR ME !...the output varies from 5v 12v-40v the list is endless , with varying amperage inc.. and then you have regulated unregulated. I realise why im not an electrician ! although I do try to understand it.

Maybe someone could explain very simply the basics and whats important and whats not ? And maybe tell me whats the supply I need ?

In basic terms im trying to get a simple power supply for a power feed for my mill.
Much appreciated help.

Chuck in E. TN · « **Reply #1 on:** November 10, 2018, 08:34:25 AM »

Buell, unless your going to convert to CNC on your mill, you don't need a stepper. A simple DC motor, like a windshield wiper motor, or maybe a motor salvaged from a cordless drill will be sufficient. The motor can be speed controlled by a cheap Chinese PWM controller, available on E-Bay. For a power supply, anything up to 30 volts is good on a 12v motor. The PWM(pulse width modulation) controller sends pulses of DC voltage to the motor, the pulse with being modulated. The wider the pulse, the faster the motor goes.
I'm not saying a power feed can't be made using a stepper, but if you're not going to cnc, simple is better. Oh, the same applies to steppers pertaining to power. Steppers are current driven, and use a stepper driver to control direction and amount of travel.
I built a X axis power feed for my X2 mill from a gear motor, a PWM speed control and an 18vdc laptop power supply. On the other hand, I built an Arduino based controller to drive my rotary table that uses a stepper for accurate positioning. It so uses a laptop power supply.

Buell · « **Reply #2 on:** November 10, 2018, 09:56:17 AM »

Thanks for the reply...You say "Anything up to 30v is good on a 12V motor " To me that just sounds crazy ..makes no sense. My brain says thats like Diesel in a petrol car is ok ! sorry probably not a great Analogy but best Ive got ! 12v to 30v is almost 200% difference Am i missing something ? And why just 30v why not 40v or say 60v !

I will be using a stepper with a Driver unit as I have just received them ..im trying to understand and tinker with this to get used to it before I try a CNC or the like.

awemawson · « **Reply #3 on:** November 10, 2018, 10:39:46 AM »

Stepper drivers chop the output to control the current through the windings. It's the current that gives you the torque and the voltages helps overcoming their inductance.

So it's not like a conventional motor where a 12 volt motor needs a 12 volt supply. My CNC Plasma table steppers are driven from a 68 volt supply but the motors are rated at only a few volts per phase.

. . . it's all in the pulses

seadog · « **Reply #4 on:** November 10, 2018, 11:56:10 AM »

" 12v to 30v is almost 200% difference"

Try 250%

John Swift · « **Reply #5 on:** November 10, 2018, 12:48:29 PM »

a rule of thumb from Geckodrive.com

" The power supply voltage is determined by multiplying the square root of the motor’s inductance by 32, as in the example below for a 2mH rated motor:

32 * (√2) = 45VDC "

the faster you need to step the motor the shorter the time for the motor current has to build up to the current you have set the drive to

the higher the motors inductance the longer it takes for the current to build up

by using a higher supply voltage you can force the motor current to build up to the set value in a shorter time

that's why your going to be disappointed with some of the Chinese cnc kits that have a 24V supply and motors with a very high inductance , about 8 mH or more with some kits

8mH stepper motors will require the driver to be powered by a 90V supply unless you want your machine to run at a snails pace

John

kayzed1 · « **Reply #6 on:** November 10, 2018, 01:48:48 PM »

Thank you John, i just found out why my rotary table runs at around 3 inch per hour

I need a good stepper motor...
Lyn.

Chuck in E. TN · « **Reply #7 on:** November 10, 2018, 02:37:17 PM »

Using a higher voltage dc supply on a dc motor by way of a pwm control module is the same as using a higher voltage supply on a stepper by way of a stepper driver. By using PWM, you are not applying the larger voltage constantly, but in pulses. I know it seems to defy logic, do some research.
Google is your friend.

Buell · « **Reply #8 on:** November 11, 2018, 12:22:43 PM »

Quote from: John Swift on November 10, 2018, 12:48:29 PM

a rule of thumb from Geckodrive.com

" The power supply voltage is determined by multiplying the square root of the motor’s inductance by 32, as in the example below for a 2mH rated motor:

32 * (√2) = 45VDC "

the faster you need to step the motor the shorter the time for the motor current has to build up to the current you have set the drive to

the higher the motors inductance the longer it takes for the current to build up

by using a higher supply voltage you can force the motor current to build up to the set value in a shorter time

that's why your going to be disappointed with some of the Chinese cnc kits that have a 24V supply and motors with a very high inductance , about 8 mH or more with some kits

8mH stepper motors will require the driver to be powered by a 90V supply unless you want your machine to run at a snails pace

John

Thanks for this I have just checked the Inductance on the Box says "Phase Inductance at 1khz typical is 2.5

so If my poor maths is correct that is 46.16v

With that in Mind ...I just need a Medium speed to traverse quickly when Not cutting and a Very slow speed for when it is cutting. Does that alter anything ?

Also just noticed the driver I bought of Fleecebay is rated at Dc 9-40vdc at max 3.5amps and 4.0 at Pk Current which i guess is at Peak current ?

Please excuse my ignorance within electronics as I know Very little and am trying my hardest to grasp a small slither of what many folk know lots.

Buell · « **Reply #9 on:** November 11, 2018, 12:41:54 PM »

Clearly I shouldn't Go over 40vdc at 4amps as thats all the Driver could handle ?

ddmckee54 · « **Reply #10 on:** November 14, 2018, 11:07:04 AM »

That's right, it's like the weakest link in a chain.

Look at the voltage ratings of all the equipment. Whatever has the LOWEST maximum rating will be the highest voltage that you use for that entire system. You can use lower voltage, within reason, and the system will still run - it will just run a little slower.

Don

Buell · « **Reply #11 on:** November 29, 2018, 05:05:39 PM »

Ok so got a few bits but super struggling with the wiring side made someone could clear the fog..all lights up nothing has gone bang ! but nothing moves or shakes or rattles yet...but locked solid when the power is on. Help

philf · « **Reply #12 on:** November 29, 2018, 05:46:54 PM »

Hi Buell,

Excuse the crap drawing (I'm not good at drawing with a mouse) but I think you need to connect it something like this:

I would connect the Direction, Enable and Pulse wires to -ve but then you need to common all the +5V terminals together and connect them to 5V. The inputs are usually opto-isolated and you need connections to both -ve & +ve.

Phil.

Buell · « **Reply #13 on:** November 29, 2018, 06:04:07 PM »

Thanks for that...finally found something online...turns out its ...

PUL+DIR+ ENA+ all together to the last terminal on the controller ..have no idea what that is as its in chinesium.
PUL - to CLK
DIR- To DIR
ENA- to En

so one other question if I had made the worst dogs dinner out of this , is there any damage i could do ? other than mains in and 24v to the wrong terminals ?

Just the beginning for me doing this kind of stuff !
Thanks for the reply this thing works !

John Swift · « **Reply #14 on:** November 29, 2018, 06:08:10 PM »

Buell

can you post a link to the instructions for the pulse / direction board ?

I expect the two terminals labled in Chinese are +5V out from the regulator IC
and the common 0v to the pulse , direction & enable outputs

for your initial test just connect the stepper driver -pulse to the negative supply terminal
and + pulse to the pulse board pulse output

PS
do you have a multimeter ?

with the meter set to ohms
you should be able to test for continuity between the negative supply terminal and the two terminals labeled in Chinese
to find out which is the 0V and which is the +5V out

Buell · « **Reply #15 on:** November 29, 2018, 06:42:07 PM »

Got it going heres a vid

Hope its ok to post here ?

Buell · « **Reply #16 on:** November 29, 2018, 06:47:57 PM »

This is what I ended up with as a visual just In case it didn't make sense. Well it doesn't to me !

Buell · « **Reply #17 on:** November 29, 2018, 06:59:57 PM »

One draw back to this wiring....It doesn't Lock The motor !! Any ideas ? I would need it to lock to stop it from moving In the mill.

philf · « **Reply #18 on:** November 30, 2018, 02:35:56 AM »

Buell,

You'd need to keep the enable input grounded to keep the motor powered to hold it. If your control board doesn't do that just put a switch in the enable line to switch the input to your driver from the control board to 0v.

Phil.

Buell · « **Reply #19 on:** November 30, 2018, 04:55:13 AM »

Quote from: philf on November 30, 2018, 02:35:56 AM

Buell,

You'd need to keep the enable input grounded to keep the motor powered to hold it. If your control board doesn't do that just put a switch in the enable line to switch the input to your driver from the control board to 0v.

Phil.

Exactly how do i do that ? On the power supply the + output goes to the GND on the stepper driver (Just that doesn't make sense to me , Ground has always been Earth to me )

philf · « **Reply #20 on:** November 30, 2018, 05:08:41 AM »

Hi Buell,

Why does the +ve from your power supply go to GND on your driver? I'm sure it shouldn't.

(Just to clarify This is to enable the enable (excuse the pun) if the control board enable drops out whilst the motor is not turning.) I can't do a sketch at the moment but you'd want a single pole changeover switch with the common connected to the input of your driver, one other connection to the Enable connection on your control board and the other to the common ground on the 5v supply.

Phil.

Buell · « **Reply #21 on:** November 30, 2018, 01:38:04 PM »

No reason other than I copied it from somewhere ! .. Clearly if you think its wrong i will change it !

Buell · « **Reply #22 on:** November 30, 2018, 01:44:15 PM »

This is how I made a Start..but then realised that the controller thing was not the same ! but seemed a good place to start !

ddmckee54 · « **Reply #23 on:** November 30, 2018, 02:13:42 PM »

Any chance that you could supply us with the manufacturer and model number of the boards that you are using?

I'd hate to see you unintentionally let the magic smoke out of your boards, and with the part numbers we might be able to find the manuals on-line and help you decode their "Chinglish".

From what I can see it looks like your set-up should work, you've got it turning so it's sort of working. But the people that write the directions are not exactly consistent/knowledgeable regarding their subject. Sometimes it requires a healthy imagination and a secret decoder ring to make any sense of their manuals.

This could be something as simple as your stepper driver board is looking for a "HIGH" level pulse on its' inputs, while your pulse/direction board is supplying a "LOW" level pulse.

Don

John Swift · « **Reply #24 on:** November 30, 2018, 03:33:52 PM »

looking at the diagram in post22
it looks like they got the stepper drivers supply wires crossed !
fortunately you wired plus to plus and negative to negative even though you using black as positive & brown as negative looks odd

and should look like the original diagram with correction

if the direction & enable switches toggle between +5V and ground/0V

you can try the second version alternative wiring diagram with 0V connected to the step , direction & enable negative terminals

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Author Topic: Power supply for Nema 23 Stepper ? (Read 18433 times)