Re: Need help with servo power supply design

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

>> John Rouche wrote:
>>Ok Jon, I need some educatin. I was under the impression the
>>geckos >made a full 60v available to the motor always with every
>>step
>.command..

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

>In a sense it does, but only for microseconds at a time. It
>applies the DC supply voltage, for a measured time, first one
>polarity and then the other. When the motor is not supposed to be
>moving or generating torque, the + and - polarity balance exactly.
>That is the same as no voltage across the motor, except for a
>little heating. This happens 25,000 times a second.

Are you saying full voltage is only applied for micro seconds at a
time? That does not sound right.

What is the pulse width of the wave and what type of wave form is
it? I haven't hooked up the O-scope yet, that's next. I thought the
gecko applied the full 60vdc (we are talkin about a 60vdc supply) to
the motors for every pulse. Granted the rise and fall of the pulse
are going to be changing voltages but that is not what we are
talking about.

We are talking about the peak voltage of each pulse, no? And if so
the peak of each pulse is gonna be the input voltage to the gecko
drive unless the gecko is doing voltage dividing which I didn't
think it did.



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

>>>> It compares commanded velocity to actual velocity in a way. It
>uses analog circuits to compare relative position (commanded vs.
>actual) and then compares the long term error (the Integral term of
>PID) and the short term change in error (the Derivative term) and
>computes how much torque to demand from the motor. This sets the
>pulse width applied to the motor.> Jon

Right, the pulse width determines the amount of "drive" not a
varying voltage, I understand that, but you said the voltage would
be varying and I don't see that? JRouche

"For instance, a Gecko 320 drive with a 60 V power supply, and
delivering 2 V at 20 A, will draw 40 W, or only 1.5 A from the power"