Laurav wrote:

On Jun 15, 8:58 pm, Jamie
t wrote:


Yes, I hear you and still, it is a mass air flow and motor design
problem..


I haven't noticed that the motor speed is sensitive to anything else
besides voltage, and the guy who makes the motor says that's the only
thing that causes changes in speed.
You could send your suggestions to Turbine Products, see what he says.
In any case I need to deal with this particular motor, not some future
version.
Laura

Regulating the voltage is only going to fix part of your problem, the
issues are that your motor design is very sensitive to RPM changes with
load changes.

If you were to sit down and attempt to calculate the difference in
voltage needed per RPM, you'll find that it's all over the place..

Motor speed in your case is like an inverse log, once you get it out
of the hole, it'll speed up greater than expected. It's all about slip
in an AC motor under load changes. AC motors do not have much torque at
the lower RPM, unless of course, you're doing vector mode, and I know
for a fact you're not doing that.

Your problem will not go away that easy how ever, a thyristor
controller may work a little better over having a rheostat, but then
again, you may have a slight drop on the high end of those.

what you have there is a low end design.. What you should have is a
brushless DC motor which requires a speed controller.. THey do make
integrated Brushless DC motors. We use them at work in vacuum loaders
and they are good at maintaining speed. They are integrated motors of
high RPM with a 0..10 volt input speed control reference. They are a
closed loop and thus can monitor its own RPM.


Jamie