Re: [CAD_CAM_EDM_DRO] servo amps and power supplies; terms of endearment

Jack,

FOR A QUICK (simple) ANSWER; there is usually a driver for the servo
motors (your boards), that receive a commanded position, and an current
position (motor encoders). These two "values" are summed (added)
together, and the result is "correction" (error) value. This error
value is usually applied to a PWM (Pulse Width Modulator) circuit, which
controls the amount of "on time" of a switch sending power from the
power supply to the motor. Also sent is the direction for the motor to
turn (the sign of the correction value). The "switch" is usually an 'H'
bridge, a fancy electric switch to allow the motor to run in either
direction. Thus the motor turns, and changes the current position,
which reduces the correction value, and the motor gets to where it is
commanded. PID will not be discussed here!

THAT is a quick (simple) answer, SOMEONE on this list can probably
identify the boards/hardware you have (what do you have?), and suggest
what you need to add! Most likely, you will need a standard power
supply that is of the proper voltage and current rating. Something to
match the motors (you have motors?).

And, I'M SURE, you can get a MORE extensive, MORE accurate description
of a simple servo system, OR the one YOU HAVE!

Hope this helps,

Alan


jmw@... wrote:

>
> I've got a servo amp with 4 boards, each rated to run a (permanent
> magnet DC servo) motor 70-100 VDC at 15 cont / 25 peak amps. The unit
> has an integrated power supply for its own requirements--but zilch
> for the motors.
>
> What I'm wondering is how the amp communicates with the power supply
> so as to vary the power supplied to the motors? Does the amp just
> tell the individual motors to run faster or slower and so each just
> pulls more or less from the well? Maybe the amp sends voltage and
> amperage codes to the power supply and it adjusts its output (but
> this would require a power chanell for each motor, right?) Maybe the
> full output of the power supply runs through the amp and four demons,
> one for each motor, regulate the flow to each motor.
>
> As I've stated before, I'm not an EE. I figure I could probably
> figure out how to make a simple DC power supply, but depending on the
> complexity of the controll scheme I might just try and find one
> surplus.
>
> As always, thanks in advance.
>
> --Jack