Re: [CAD_CAM_EDM_DRO] Gecko's ok on a switching power supply

sprooney797 wrote:

> I asked this question about a month ago, but no one had any comments.
>
> Is it ok to operate gecko drives from a switching power supply if it
> is rated for the correct current? Or is a linear supply preffered?
>
> Does it make a difference??

The Gecko drives will have substantial fluctuations in current draw,
which may upset some regulated power supplies regulation
circuits. One nasty fature of motor drive is that power is extracted
from a decelerating motor and fed back to the power source.
If the power supply has over-voltage protection (crowbar) it
may cause the power supply to shut down vigorously, shorting
out the geckos and motor. It would probably be good to raise the limit
on the overvoltage protection to 80 V, or at least a good margin
above the nominal voltage.

Actually, here's a reason why switching power supplies may not
work well. An unregulated supply will have a huge capacitor for
bulk DC storage, and the braking current will raise the voltage on
it only slightly. A regulated supply (either switching or linear) will
have small output capacitors, and generally will not allow current
to flow back to the bulk capacitor. So, braking will rapidly raise the
output capacitor voltage, possibly damaging the power supply or
causing an overvoltage trip on supplies so equipped.

The fix is to add external capacitor banks (which could destabilize
some regulators) or a braking resistor circuit that switches on
when the voltage rises above a safe level.

This is why non-regulated supplies are easier to use in this
application.

Jon