RE: [CAD_CAM_EDM_DRO] DIY AC servodrive questions

Anders,

I'd have to know more about your drivr/motor topology. Commecial
drives are usually configurable for torque or speed. PID is just a
cause/effect thing and will work with torque signals, velocity signals, or
even open
loop amps. The tuning is different.

Let me ask a simple question about what you have now:

If the motor is running at speed with some control voltage input....and if
you suddenly
make the input control voltage zero...does the motor coast or stop abruptly?

Les


Leslie M.Watts
L M Watts Furniture
Tiger Georgia
(706) 212-0242

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-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com]On Behalf Of Anders Wallin
Sent: Monday, June 05, 2006 6:04 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] DIY AC servodrive questions


Hi Les,

Thanks for the quick and informative reply.
It looks like I won't have to develop more microcontroller code then -
nice, since it's not my strength nor very interesting !

As I tried to describe the servodrive reads an analog voltage and
outputs sinwaves with this voltage amplitude. Wether that makes it a
speed or torque drive I don't know... In principle the drive input
controls speed, but it's open-loop, i.e. when there is load a higher
input needs to be applied.

When running in this mode (no speed or torque loops closed in servodrive
hardware), are there any special considerations for the PID loop that
runs in EMC ? (other than 'normal' PID tuning - which in itself seems
to be somewhat of a black art...)

AW