Re: [CAD_CAM_EDM_DRO] Re: +/- 10V Gecko

mariss92705@... wrote:

> Jon,
>
> Hi. What I'm designing is an amplifier. As such it can be configured
> as a voltage amplifier or a transconductance amplifier. Any time you
> close the loop, such as using a tachometer and/or encoder it becomes
> a servo.
>
> A voltage amplifier behaves exactly as you describe in closed loop
> operation. This is primarily because of the additional 90 degree
> phase lag introduced when compared against a transconductance
> amplifier. IR compensation introduces phase lead which improves the
> loop phase margin somewhat.
>
> A voltage amplifier has uses other than driving a motor.

Certainly!

> You caught me out regards to IR compensation. To be practical, the
> feedback pot must be a multi-turn type because of the exquisite care
> with which it has to be set to get decent speed regulation. I have it
> front mounted.

Ah, that makes sense.

> I am looking at including tach feedback summing node but I am put off
> by the interior loop feedback phase compensation adjustments. Witness
> the plug-in capacitors and resistors necessary on Copley and other
> amplifiers.

Yes, when you have to tune the servo, it gets complicated, indeed!
But, when it is right, the performance is outstanding, and beats anything
else that doesn't do the actual velocity feedback in some manner.

Jon