RE: [CAD_CAM_EDM_DRO] AC Servo Motors and Drives

When one talks about AC servo motors , it usually refers to the commutation
of the phases. If the commutation is sinusoidal then the motor is referred
to as an AC servo motor or a sinusoidally commutated DC servo motor. If the
commutation waveform is not mentioned explicitly, one assumes that the
waveform is six step or trapezoidal (using hall effect sensors directly for
the commutation information). That said, to run these motors you can use
both sinusoidal or trapezoidal commutation although the sinusoidal
commutation has a number of advantages (lower cogging etc) and a few
disadvantages (primarily the processing required to produce the switching
sequence for the six MOSFETS to produce a sinusoidal output). Most servo
drives support both types of commutation and I am not sure if the Geckos do.
Madhu

>-----Original Message-----
>From: aussiedude36 [mailto:aussiedude@...]
>Sent: Wednesday, September 24, 2003 1:18 AM
>To: CAD_CAM_EDM_DRO@yahoogroups.com
>Subject: [CAD_CAM_EDM_DRO] AC Servo Motors and Drives
>
>
>Hi group, I have been playing with CNC stuff for a while and have
>built a couple of systems with steppers and Dc servos utilizing
>Geckos but I recently ended up with some AC Servo motors. As I
>understand it they are kind of like 3 phase motors in the way they
>work, 1) am I right & 2) are there any gecko / inexpensive type of
>drives to run these motors using step and direction pulses?
>Any direct answers or pointing in the right direction would be
>greatly appreciated.
>
>David