RE: [CAD_CAM_EDM_DRO] Re: Question on Power Supply - regulated notes

HI Dave,

I wonder if there isn't a difference between a servo motor and a stepper in
decelerating. Mariss has measured back EMF on the steppers, so we know it's
there, but we still have to step the stepper motor. Probably a smaller
current "drink" from the power supply. But as the windings still get
energized, then I'd think we would still have drive power to cancel back
EMF.

Now on servos it's obvious that there is EMF. We actually drop the drive
from a motor (small peristaltic pump) for a short bit of time in order to
measure the back EMF, and use it to control the speed (servo loop).

Good paper, by the way!

Alan KM6VV

> -----Original Message-----
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of turbulatordude
> Subject: [CAD_CAM_EDM_DRO] Re: Question on Power Supply - regulated notes
>
> --
> > Some folks say to use unregulated power supplies mostly to deal with
> > back voltages (BEMF) from steppers.
>
> (Apologies in advance if I'm playing fast and loose with terms and
> technology, but as a general overview this pretty much covers the bases)
>
> Mariss had done a great write-up on this. the regulated PS's have a
> chip called a voltage regulator. This. well. regulated voltage.
>
> DC motors spinning without power are generators. So, when you are
> decelerating a load, the weight of the machine (some MUCH worse than
> others) will try to spin the motor faster, but the driver is
> decelerating. The result is the motor is putting power back into the
> power supply.
>
> <SNIP>
> OK, starting to ramble.... signing off.
>
> Dave
>
>