Output voltage from mains driver?

[JW1977]

Hej!
Thank you, interesting to see!

The Leadshine DM2282 is a "mains" driver, ( 220V.)
If I would have used the AM882, the stepper would have got about 75V.
That’s a little more than the calculated max (66 V) but i guess it would have worked.
With the DM2282 I get more margins and I won’t have to build another PSU so the cost will be about the same.
I know it works because I can see it being recommended here and there but I can’t get what the output Volts will be?

[A_Camera]

Hej!
Thank you, interesting to see!

Hej igen!

Thanks.

The Leadshine DM2282 is a "mains" driver, ( 220V.)
If I would have used the AM882, the stepper would have got about 75V.
That’s a little more than the calculated max (66 V) but i guess it would have worked.
With the DM2282 I get more margins and I won’t have to build another PSU so the cost will be about the same.
I know it works because I can see it being recommended here and there but I can’t get what the output Volts will be?

The way I interpret the manual of the DM2282 is that it can use DC or AC supply. The DC input range is 115~305VDC and the AC is 80~220VAC. It is NOT the mains you normally connect to the input directly, but through a transformer.



I see two major reasons for this, one is personal safety, the other is that the mains in Europe is NOT 220V, so I would not connect it directly to the mains. Basically, if you want to build a PSU, that's fine, but regardless of which, you don't need it if you use the DM2282, you just need a transformer, but if you build one you can still use the DM2282 because it can use both DC and AC supply.

Here is a link to the manual, in case you have not seen it yet:

http://www.leadshine.com/UploadFile/Down/DM2282d_P.pdf

My guess is that the output voltage will be (if using AC as supply): 1.41 x the AC supply voltage. If DC supply is used then the output will be the same as the input voltage if measured as I measured the voltage.

[m_c]

A_Camera, for those kinds of tests, you really need to use an oscilloscope, and you might want to see what happens when you put some extra load on an axis (even just lean on the Z axis as it runs), and at varying speeds.

JW, either drive would work. If you never run the motors at high speed (or not for long periods of time), then a higher voltage should not be a problem. A higher voltage would give better acceleration/performance, but the big risk is overheating the motor. That could be counteracted by reducing the current, but then you would lose torque.

You do realise that even though the DM's are high voltage drives, you still need to provide an appropriate input voltage? So the only thing you would realistically save, is a bridge rectifier and capacitor(s), as you'd still need an appropriate transformer.

[A_Camera]

A_Camera, for those kinds of tests, you really need to use an oscilloscope, and you might want to see what happens when you put some extra load on an axis (even just lean on the Z axis as it runs), and at varying speeds.

Yes, I know, but I did not want to hook up my scope because I might fry it (or the driver) since it is not isolated from the mains so I might get a grounding issue. If I had a battery driven scope I would have hooked that up, but I don't.

Regarding extra load, I am not sure it matters, I believe it does matter, but just recently had a discussion about that on CNC Zone, and one person said it does not matter. Basically because steppers are not real motors, just some solenoids which are switched on and off to get the motion we want. I don't know, but I believe (have a sense) that he is wrong, current will increase (to the maximum limit set up on the driver) if the motor is under load. Maybe that will be my fourth measurement...

JW, either drive would work. If you never run the motors at high speed (or not for long periods of time), then a higher voltage should not be a problem. A higher voltage would give better acceleration/performance, but the big risk is overheating the motor. That could be counteracted by reducing the current, but then you would lose torque.

You do realise that even though the DM's are high voltage drives, you still need to provide an appropriate input voltage? So the only thing you would realistically save, is a bridge rectifier and capacitor(s), as you'd still need an appropriate transformer.

Yes, it is VERY important to use a transformer since 230VAC x 1.41 = 325V and that is VERY high for steppers and extremely dangerous to use in our DIY machines. I am not sure that the steppers will survive that, not even for short periods.

[m_c]

Solenoids take more current if you load the plunger, as you disrupt the magnetic field. The essential law of physics, that you don't get anything for nothing, applies.

If I had the time, I'd built a dynamometer to run some tests. I have the plans for one, just not the time.

[A_Camera]

Solenoids take more current if you load the plunger, as you disrupt the magnetic field. The essential law of physics, that you don't get anything for nothing, applies.

Yes, that was my argument also, but since I have not measured it, for me that's just based on logical thinking and what I also learned a long time ago. Never the less, I won't argue further with him about it, so I dropped that question. Also since measuring the current is not that easy with my instruments, it is not easy to present a proof so for now, moving in air will do but yes, I expect some significant current increase if I'd measure under load.

If I had the time, I'd built a dynamometer to run some tests. I have the plans for one, just not the time.

Well, time is ALWAYS a constraint. If we do something boring then the time never ends and a minute might feel like an hour, if we have fun the time is over before we know it and an hour might feel like a minute... :)

[JW1977]

JW, either drive would work. If you never run the motors at high speed (or not for long periods of time), then a higher voltage should not be a problem. A higher voltage would give better acceleration/performance, but the big risk is overheating the motor. That could be counteracted by reducing the current, but then you would lose torque.

You do realise that even though the DM's are high voltage drives, you still need to provide an appropriate input voltage? So the only thing you would realistically save, is a bridge rectifier and capacitor(s), as you'd still need an appropriate transformer.

Yes, i realise that, now. I thought the DM2282 had a built in PSU ready for mains DC.
As i mentioned above, optimum would be about 66V for the stepper and the PSU would give about about 68V IRL if use a 50V transformer.
AM882 can be supplied with up to 80V and handle 8,2A so the figures add upp pretty nicely.
Leaning towards 3x AM882. (Can they be bought fair closer than China i wonder?)