Running 3 x Stepper Drives from 3 different mains Phases?

Hi Guys, First post here I think!

I am retrofitting a machine that has a 3 phase transformer with 3 x 83vac output phases in delta. I don't really want to run a separate switchmode but I may just do that if this doesn't work.

I want to run the Stepper drives ( Leadshine hybrid drives) on each setarate 83vac phase output from the transformer.

Originally those phases were crudely rectified and smoothed with a dirt great capacitor and then drove the original centroid DC servo driver.

I'm pretty sure it will work but maybe someone has done it and knows it won't??

Am I crazy ? thanks guys for listening.

And Hi from Australia!

cheers,
Lachlan.

It will work if the drives want 83VAC.

If the drives want DC, you'll want to rectify all phases onto a common DC bus. That way you will have 1/3 or so of the ripple you would have with three seperate single phase rectifiers.

There is also the benefit of only needing 6 diodes and a capacitor, versus 3 full rectifiers (or twelve diodes) and three capacitors. And this way you can have your negative rail at ground potential, which is much better for safety, ease of construction, and mitigating interference.


You probably already know this but 83VAC makes 117VDC. That transformer will likely put out a fair bit above 83VAC under no light load conditions as well. Be sure your drives can handle the voltage.


EDIT: I would just use the original rectifier and replace the capacitor and feed that into your drives.

Strostkovy said:

It will work if the drives want 83VAC.

If the drives want DC, you'll want to rectify all phases onto a common DC bus. That way you will have 1/3 or so of the ripple you would have with three seperate single phase rectifiers.

There is also the benefit of only needing 6 diodes and a capacitor, versus 3 full rectifiers (or twelve diodes) and three capacitors. And this way you can have your negative rail at ground potential, which is much better for safety, ease of construction, and mitigating interference.


You probably already know this but 83VAC makes 117VDC. That transformer will likely put out a fair bit above 83VAC under no light load conditions as well. Be sure your drives can handle the voltage.


EDIT: I would just use the original rectifier and replace the capacitor and feed that into your drives.

Click to expand...

****EDIT: SORRY I STUFFED IT UP ITS 70VAC AND 100VDC.....SO DONT WORRY ITS A MOOT POINT NOW*******

Thanks for the reply, sorry I didn't clarify , no the drives can take up to 100vAC OR 70VDC

I was not planning on rectifying the 3 phase and am ditching the existing 3ph rectification and yes the voltage would then be too high anyway :-(

I do have a 117vac single phase tap on that transformer that I'll drive a switch mode 60vdc power supply if needed or just 240v from one of the machines incoming phases (pre-transformer Y configuration with a neutral)

I worry that the internal rectification doesn't isolate the AC Properly from the chassis and signal signal grounds. These Leadshine Drives may not have proper isolation.....I'm sure they're ok on the same phase but my main query is the fact that they would be on separate out of phase phases!!

Hope that makes sense. yes I actually studied electronics but I'm so out of practice these days on the AC power stuff its all a bit muddy.

Just run them from one line.
They will stabilise each other and the power dumped is small anyway.

Imho the leadshine drives are likely to be more than good enough re: isolation.
For about 4 years the import drives have been excellent with good soft start, anti jitter circuits, short-circuit protection and signal/noise stability.

Steppers are slow and store little energy.
Mostly.

hanermo said:

Just run them from one line.
They will stabilise each other and the power dumped is small anyway.

Imho the leadshine drives are likely to be more than good enough re: isolation.
For about 4 years the import drives have been excellent with good soft start, anti jitter circuits, short-circuit protection and signal/noise stability.

Steppers are slow and store little energy.
Mostly.

Click to expand...

Thanks for the information. I have an unregulated supply from leadshine. hopefully it will be fine.