RE: [CAD_CAM_EDM_DRO] Just an idea

Even simpler, couldn't you just use really BIG caps and avoid the battery
charging circuitry?

By the way, I'm impressed by what you guys are doing, and am very eager to
hear more about your upcoming step/dir servo amps.

Carlos Guillermo
VERVE Engineering & Design

> -----Original Message-----
> From: Mariss Freimanis [mailto:geckohall@...]
> Sent: Friday, June 16, 2000 12:23 PM
> To: CAD_CAM_EDM_DRO@egroups.com
> Subject: [CAD_CAM_EDM_DRO] Just an idea
>
>
> Has anyone used a battery in conjuntion with a servomotor power
> supply?
>
> Reason for the question:
>
> Brush DC servomotors have peak torque values that are up to 10 times
> their rated continuous torque, thus peak current draw can be up to 10
> times the continuous draw. This peak current event can last from 10
> millisec to 1 second and the duty cycle must be under 10% to stay
> within the motor's dissipation rating.
>
> Unfortunately the power supply has to be sized to this peak power,
> when on average a supply 1/10 the size would do.
>
> My idea would be to use a small NiCad or NiH battery connected to the
> power supply output bus via a diode. During a high current pulse the
> power supply voltage would sag, the diode would forward bias and pick
> up the load for the duration. A quick-charge IC would handle the
> charge restoration to the NiCad between the pulses.
>
> Even little AA .5 AH NiCad cells would do; a 25 Amp, 1 second load
> would discharge only .007 AH (25Amp / 3600 sec). The internal
> resistance of a Nicad cell is on the order of .02 ohms, so they are
> quite capable of supplying this level of current.
>
> It seems a 100 watt supply / battery combo could replace a 1kW
> supply. Has this been done before?
>
> Mariss
>