steppers VS Switch mode power

[CNCezee]

Hi Guys,
I have been looking around while building my router, and I have noticed a large degree of conversation about stepper power supplies.
100% of which are old fashioned linear rectifiers, transformer AC to DC conversion and a filter capacitor.

But no mention of switch-mode power supplies???????????


Any reason why?? because i have a real beauty 22.0 ~28.5 volts at 50 amps.

It woild be a real shame not to be able to use it

Roger

[pastera]

Most switchers a single quadrant units, meaning they cannot accept power from the load.
You would need to add a diode to block the motors from pumping the supply and a means of dumping the extra charge when deaccelerating the motors

Aaron

[CNCezee]

Thanks That is all i needed.

to look at my machine go to www.foundry-fopars.co.uk, and navigate to the CNC link.

Roger

[jerber]

I use a 22-26V 10A switched supply buffered with two 10.000 uF capacitators on the ouptput. It works fine.

There's a document on http://www.geckodrive.com/support.cfm, called Step Motor Basics.pdf, wich says it's ok to use a swithed supply with a 2.000 -10.000 uF capacitator on the output terminal.

[CNCezee]

Many Thanks, I did notice once whilst testing the vast improvment on stepper preformance when a large cap was put accross the supply rails but i put this down to filtering and not dumpung power from the stepper.

In any case i will add both caps across motor supply terminals and accress the PSU.

Cheers Roger