Hey, gang.

wrote:
On 22 Jun 2005 13:46:10 -0700, wrote:

In "Motor/Generator Analysis Redux" I wrote, but nobody replied to:

SNIP

I feel resonances. It's not intuitive.


Would replacing the rotor "windings" with copper wire or bus bar
(easy), and rewinding the stator with bigger wire (hard) have any
chance at all of working together by lowering the leakage inductance
and rotor resistance to allow resonance?

You've been wading in pretty deep water - although, at first
sight a self excited squirrel cage alternator sounds like a simple
device they're a positive feedback system. They're so touchy that
they're pretty well only used by dedicated amateurs - I don't know of
a single commercial application.

Note - this refers only to SELF EXCITED alternators. The same
machine driven at over synchronous speed and connected to a power grid
works fine as an induction alternator and will feed back to the power
grid the equivalent of it's mechanical input power less its generation
losses. This works well in commercial wind power sytems.

I've got a medium sized DC permag motor and not one but two inverters.

Is there a load-sharing or four quadrant inverter I could add to my
collection to experiment with what I do already recognize as much
simpler synchronous, non self-excited operation?

I'd drive the generator with the rear wheel as detailed at
ftp://users.aol.com/DGoncz/Bicycle and in other posts, and invert the
output as I did on January 1, 2005, to the hilarity of my neighbors,
using the sine wave inverter this time, drive the motor on one phase,
and collect power from the other, or, with a load-sharing or four
quadrant inverter, put the ultracapacitors back on line between the
generator and inverter, and use both phases of the motor as a
synchronous generator.

I really don't think you'll have much luck unless you move to a
decent size 4 pole machine and even then I doubt that you'd be very
happy with the results. A small permanent magnet DC motor is soooo
much easier and cheaper!

Been there, done that. See ftp://users.aol.com/DGoncz for the video.

I want, in all this work, to *feel what it's like* in my muscles. I
just have this incredible appetite to gage levels of power from 1 -
1000 watts as muscle power, in convoluted ways. I want to feel the
positive feedback "kick in" when I pedal my generator. That's what I
live for, and for the occasional stunt. It's like having an appetite
for kinky sex, not that I would know what that is like.

I'm sorry if this is a bit disappointing but it's all useful
experience and, sadly, experience is usually gained the hard way. You
picked a very tough one for yor first project - better luck next time.

Jim

No, it's OK.

If I replace the grease in my generator's bearings with light oil, it
will rotate even more easily. This brings to mind the opportunity for
winter operation. That brings to mind room temperature superconductors,
which we don't have yet, but also the thermal coefficient of electrical
resistivity, which is a known property. It may be at some low
temperature, with the right bearing lube, R may indeed by less than
sqrt(L*C), allowing resonant operation.

How low do I have to go?

That is, do I need a Dewar of Freon, Nitrogen, Helium, or Hydrogen to
lower the coefficient of electrical resistivty to the point resonance
is possible? Dr. Majewski would certainly support such an effort.

I'll go check now....

Doug