Newbie PSU calculations

[dazp1976]

That would be a mistake for several reasons. First, 48V is too close to the drive's maximum voltage so any back EMF from the steppers when slowing down could damage the drives as it returns to drives and spikes above 50vdc.

Secondly, the regulated DC supply will cause problems for similar reasons, because steppers basically become dynamos when de-accelerating the voltage being feedback to the PSU will cause the supply to clamp and possibly shut down. This will be erratic and unpredictable and leads to all kinds of issues that not always obviously related to the PSU.

This is why Unregulated PSU is often used or better still toroidal transformer with smoothing capacitors for DC drives which will absorb any back EMF. Also, an unregulated toroidal setup allows lower power requirements, approx 60% of total stepper current, because of the way it works with the pulse modulation of the drives only needing power 50% of the time.

Using drives that accept AC input is becoming more popular because it removes the need for smoothing capacitors and rectifiers needed for converting to DC voltage, but still the use of an Unregulated PSU or toroidal transformer is required for the reasons stated above.

You'll have to build him a toroidal DC then if tha's the case.

1: Even if you could get one in the uk it will be at stupid cost!!!!!. Importing coats even more!
2: Op likely (like me) wouldn't have a clue or the confidence to have a go at building one.
3: Not going to buy different drivers (again).

I'd have gone either DM860 type drivers and 60Vdc switched. Or ones that can take up to 70Vac straight off a base toroidal, all day long.
He has what he has!!!!!
Just turn the regulated down to 45V if you're that concerned.


I use DM860 and 60V right now and it's never failed me.
I've also recently got my first Lichuan A4 servo set (for spindle use), and I'll be going that route later down the line.
Overspent for the next 6 months!.