Re: Another Possible Lower cost Servo Controller?

Gents,
In looking at the specs of AC Servo motors, I realize that most are three
phase motors with the required encoders/tachs and or resolvers added on to
the back. Granted they are optimized for positioning systems (usually) and
are not designed to be run at high speed for long periods of time. My
question is, with many of the more advanced VFD's on the market, you can
control velocity and direction with standard +-10 volt inputs. I again
understand that VFD's are not optimized for positioning but what harm would
there be in pressing a 3 phase motor / VFD / encoder set up into CNC service?
The VFD's are significantly cheaper than AC Servo drives in most cases. If I
am totally off the mark, please tell me why. TIA.

Peter
PT Engineering Co.