Re: [CAD_CAM_EDM_DRO] Re: AC drives

AC servo and DC brushless motors are I believe one and the same for all
intents and purposes.

An induction motor cannot be described as a servo motor as its low speed
performance is generally a bit rough. To produce torque you have to induce
current in the rotor that at very low frequencies and speeds is not very
efficient. With permanent magnets on the rotor (ie your ac servo motor) the
rotor flux is permanently established.

Regards Peter

----- Original Message -----
From: "gittt2000" <gitlang@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, November 05, 2002 11:21 AM
Subject: [CAD_CAM_EDM_DRO] Re: AC drives


> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
>
> > DC Brushless motors are really misnamed. THEY are truly
> synchronous
> > motors. AC servo motors
> > are VERY similar to ordinary AC induction motors, and they ARE
> > asynchronous, as they have to be
> > for the induction principle to excite the rotor.
>
> I've been confused between DC Brushless and AC synchronous Servo
> motors and thought I'd sorted this out, but now I'm confused again.
>
> The MAC AC Servo motors by Indramat (now Bosch Rexroth) are described
> as synchronous but they are not similar to ordinary ac induction
> motors. They have a wound stator, electronic commutation, and a rotor
> comprised of 6 (or another multiple of 3 presumably) permanent
> magnets, rather than the squirrel cage of conductors which form the
> normal induction motor rotor. As far as I can see there is no
> induction involved - the stator produces a rotating magnetic field
> and the magnetic rotor follows it. What makes it synchronous is the
> commutation which signals the servo drive to supply the correctly
> phased stator drive.
>
> How would you describe that type of motor?
>
>
>
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> Moderator: jmelson@... timg@... [Moderator]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>