RE: [CAD_CAM_EDM_DRO] Re: Servo motor voltage

I understand your argument about the raised voltage. But I believe others do it, so there must be a reason. I don't understand all the details about power supplies, but I do know you have to be careful with the type of power supply you choose for a servo drive. You shouldn't use a regular switching power supply by itself. I bought my powersupply from copley to go with their accelus servo amp. Copley does mention that you should have the diode if you are using a switching power supply. See: http://www.copleycontrols.com/motion/downloads/pdf/Accelus_Card.pdf On page 5, it says:
"Operation from regulated switching power supplies is possible if a diode is placed between
the power supply and amplifier to prevent regenerative energy from reaching the output of the supply."

Maybe someone could explain the reason a little better?

Darcy

-----Original Message-----
From: Mariss Freimanis [mailto:mariss92705@...]
Sent: Wednesday, April 02, 2003 6:02 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Servo motor voltage


Darcy,

Bad advice. That diode will certainly wreck most drives; where is the
returned energy to go then?

A 20mH motor carrying 20A has 4 joules of stored L*I^2/2 energy. 4
joules of energy delivered to a 55,000uF capacitor would raise its
voltage by only 12V.

Because there is no compelling reason to return the servo "brake"
energy, we use a non-regenerative switching topology. The mechanical
energy is dissipated in the motor rather than being returned. Only
the inductive component must be dealt with.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Parker, Darcy "
<dparker@p...> wrote:

> Some other advice, make sure there is sufficient capactiance and a

diode to prevent regenerative current from the motor during braking
from wrecking the power supply.

>
> Darcy

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