Re: Power Supply - Gecko White Paper

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
<mariss92705@y...> wrote:

> There seems to be a little bit of confusion on a couple of points:
>
> 1) Any motor (stepper, servo, squirrel in a squirrel cage) delivers
> power to a load. It's efficiency will always be less than 100%, so
> delivering power to a load will incur additional heating in the
> motor. The power supply must account for both. Power supply current
> must increase with load.

In re-reading the White paper, the graph on page 13 shows the copper
losses and the iron losses.

it appears that the 4 amp, 3 volt motor would have a constant 12 watts
of copper losses and the iron losses would increase with the power
supply voltage.

Also, since power is proportional to power supply voltage that offers
another key to the answer.

I think the 'power is proportinal to votage' was part of what I had
missed ealier. since the 3 volt motor can take 75 volts at 25x the 4
amps would make the motor copper losses 12 volts. The iron losses
would increase to about 43 watts at 75 volts. Combine these two for
55 watts lost in copper and iron losses.

PLUS add the power of the motor or 12 watts times 25x or 300 watts
plus 55 watts for a total of 355 watts for the motor.

divide that by the 75 volts to get 4.73 amps.

Slightly more than just using the base amps regardless of voltage.

At least the theory is staring to make sense now.

Dave






So, it would seem that the current would