[the great waldo]

Hi
I intend to get 3 of these https://www.omc-stepperonline.com/1-...or-driver.html

and run them with a 36 volt power supply. How much current should the power supply be able to handle. Also would a switching power supply need to supply more current than an unregulated supply. I was thinking of using one of these https://www.omc-stepperonline.com/po...-s-500-36.html is this supply big enough.

Cheers

Andrew

[peteeng]

Hi Andrew- You should read the data sheets. The motors are 5.8A and the PS is 14A. 3x5.8A is 17.4A. Since you wont run the motors at the same time and same duty you will not need 17.4A. 14/17.4=80% capacity. I think this will work. If it does not work it means that your motors will not be able to provide full torque. Depending on what you are doing this maybe good or not. There is no difference in a unregulated vs regulated at a simple level. Go for it and keep us posted on results. Peter

[phomann]

Hi,
To work out the current needs, multiply the rated current of all thee motors by 2/3.

Cheers
Peter


Sent from my iPhone using Tapatalk Pro

[dazp1976]

I would go the full 48v using 2 supplies myself.
Put a 12A on the X & Y.
Put a 10A on the Z.
Will give you the opportunity to get the full grunt from the systems.
Just like these:
https://www.cnc4you.co.uk/Breakout-B...U-48Volt-12Amp
https://www.cnc4you.co.uk/Breakout-B...U-48Volt-10Amp

Then because you'd have extra capacity available from the 10A on the Z. I'd prob then use voltage step downs to power the drive boards (ie: 5v, 12v, 24v) from there.

[the great waldo]

I would go the full 48v using 2 supplies myself.
Put a 12A on the X & Y.
Put a 10A on the Z.
Will give you the opportunity to get the full grunt from the systems.
Just like these:
https://www.cnc4you.co.uk/Breakout-B...U-48Volt-12Amp
https://www.cnc4you.co.uk/Breakout-B...U-48Volt-10Amp

Then because you'd have extra capacity available from the 10A on the Z. I'd prob then use voltage step downs to power the drive boards (ie: 5v, 12v, 24v) from there.

The driver manual recommends 36 volt as a supply voltage to stop problems with back emf ?

Andrew

[dazp1976]

The driver manual recommends 36 volt as a supply voltage to stop problems with back emf ?

Andrew

Can't see too much trouble if cables are shielded.
Anyway. Using the inductance formula I see around. It shows optimum voltage of 45v to get best power from motor.

You can always tweek the 48v supplies down a little.
If you use 36v and are anyway disappointed it's not like you can turn them up.

[peteeng]

Hi Great Waldo - The PS you have picked has a DC output adjustable 32-40V so you have that to play with, I'd go at 40V. Back EMF is usually an issue with lower voltages then 30V with this sort of system or with large decelerations. The higher the voltage the better the performance vs back EMF at higher speeds, low speeds back EMF is negligible. As we do not know what your desired speed range is I can't say if its a problem or not. The usual equation 32*sqrt (inductance) gives 46V max so if a 45-46V PS is there I'd pick that because it's still in the parameters of the Drivers (48V peak). But I don't think you will see a diff 40V vs 45V it will come down to the quality of the driver. Cheers Peter

Edit - as you can read from the selected driver manual it recommends 36V for good reasons. So Start at 36V if high speed needs more grunt wind up the voltage to 40V. Use the lowest voltage that gets your job done because over voltage just means hotter motors that run rough. The rest of the driver manual looks good I think it's a good driver.... looking at the data sheets it charts the delta of 36V vs 48V so there's an answer if you need the extra torque at speed.

[the great waldo]

Hallo Peter

Thanks for the reply.I think I shall go with the three 36 volt supplies. There is a 17.5 amp 36 volt supply available with pfc but it works out at about twice the cost.
https://www.ebay.at/itm/Schaltnetzte...QAAOSwEMddjRHi
A more elegant solution size wise. I shall have to a think about that. The debate is still open in my head. Also three seperate power supplies don't get so strained as a single, I assume?
cheers

Andrew

[peteeng]

Hi TGW - Cost of units is relative to consumption volume so bigger units sell less and have more costly parts due to increased specs of components. A correctly speced single PS will perform the same as multiples. But go with the least cost solution. Also remember to correctly match the amps of the driver to the motor. When first running I suggest you set them low to be safe, then as you get the parameters of speeds/accelerations etc dialed in you can crank the amps up to matching values. 6A in the wrong wire creates a lot of smoke!! Its always an exciting time when you get all those LEDS lite up and motors moving....Good luck Peter

[the great waldo]

Thanks for the tips Peter. It'll be a little while before I can get all this together and I still have to assemble the cnc machine ( https://www.sorotec.de/shop/Portal-m...-DIY-4863.html ) It was a little bit pricey but everything was supplied. I don't have much space so at the moment i'm working with my old machine with acme threads which works but makes some horrible noises when running a bit faster. I want to get the controller and electronics all ready to go before I put the machine together and swap machines. Unfortunately I don't have a lot of free time so it's all a bit of a juggle.
Cheers
Andrew

[the great waldo]

Hi TGW - Cost of units is relative to consumption volume so bigger units sell less and have more costly parts due to increased specs of components. A correctly speced single PS will perform the same as multiples. But go with the least cost solution. Also remember to correctly match the amps of the driver to the motor. When first running I suggest you set them low to be safe, then as you get the parameters of speeds/accelerations etc dialed in you can crank the amps up to matching values. 6A in the wrong wire creates a lot of smoke!! Its always an exciting time when you get all those LEDS lite up and motors moving....Good luck Peter

Hi Peter
I was just wondering would I need to use the tuning software for these drivers as there don't seem to be any dip switches to set the current on the drivers.
Cheers
Andrew

[peteeng]

Hi TGW - Hi andrew you do need to read the data sheets Looking at the dip settings there is no current control. There is autotuning and other stuff. Cheers Peter

[the great waldo]

Hi Peter
I was just replying to "remember to correctly match the amps of the driver to the motor" ? The motor driver kit mentioned in my original post should have a matching driver for the supplied motor. Correct me if i'm wrong. I don't mean to pedantic. The motor is rated at 5.8 amps and the driver rated at 8amps so should be an ok match.
Cheers
Andrew

[peteeng]

Hi Andrew - Seems this driver is configurable via software supplied not dips. So the current can be limited. But most of the functions also seem to be on auto as its a sophisticated unit. I'd start with everything on auto and only fiddle if needed. I have not used this type of driver before but I'm considering it for my next machine... Cheers Peter

[the great waldo]

Ok Thanks Peter

Andrew

[the great waldo]

Hi Andrew - Seems this driver is configurable via software supplied not dips. So the current can be limited. But most of the functions also seem to be on auto as its a sophisticated unit. I'd start with everything on auto and only fiddle if needed. I have not used this type of driver before but I'm considering it for my next machine... Cheers Peter

I'll be interested to see where the software is to be found! or maybe they use the leadshine software?
Cheers
Andrew

[dazp1976]

I wouldn't worry at all about the current difference between motor and driver, it seems to me to be a good match.

I am under the assumption the current is set automatic on these closed loop and basically send what the motor asks for.
So say your motors are 5A and the driver 8A. Looking at this page about the correlation between peak & rms:
https://www.amci.com/industrial-auto...r-peak-current
It shows the more microstepping you use, the higher your current needs to be?

I don't know much but this explains to me now why my cheap 425oz Nema23's on my Sieg seemed to have more torque the lower my microstepping was set. My motors are 4.2A and drivers are 4.2A peak. So if I'm microstepping above 1/2 it's telling me my peak should be set to 4.2A x 1.414 which is 5.93A. I can't reach that so it tells me that average 'kits' are a bit junk! and why my 23 performance is lacking. Especially only running 36v. That's at least 1/4 power loss on V and another 1/4 loss on A.

I'm changing my 23's over to 60v and 7A drivers soon.

I still say the 45v area is optimal for your closed loops.
When I future upgrade my 25LV machine I'll get similar closed loop motors but go 80Vac drivers instead. Then power from a 2x35vac secondaries toroidal wired in series to give me 70v.

[the great waldo]

Hi Daz
Food for thought.
cheers
Andrew

[GEBrown]

I have these same motors and drivers and am working on an upgrade from my current open-loop steppers. I have been reading and debating the same question: 36V or 48V? So this thread is very timely for me.
Thanks!

[diylover]

Hi, have you read the torque curve of the stepper motor, it's useful. https://www.omc-stepperonline.com/do...rque_Curve.pdf