Re: Gecko's ok on a switching power supply

Jon,

Thanks for the detailed reply. I will stick with a linear supply.

Sincerely,

Paul Rooney

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> 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