The ultimate generator?

[mkdutchman]

I really like using google patents, fascinating to see what other people have come up with

http://www.google.com/patents?hl=en

Now, take a look at this one

http://www.google.com/patents?id=464YAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q=&f=false

In a nutshell, they claim to be using an extra set of windings on a three phase induction generator to control the rotating stator field. The major benefits they claim are controllable frequency, voltage, and power factor, at any speed and load. They also claim to be able to operate the generator at turbine speeds, all the way up to 80,000 RPM+, with some absolutely insane power ratings, 20kW out of a 2 inch by 2 inch rotor at 97% efficiency in the example given...........

I am still soaking up all I can about AC theory before I start on my own power system, so a lot of what's in here just flies over my head (yet)

would like to know if anyone has/had any experience or insight into something like this

[mobile_bob]

MKD:

i took a gander at the writeup and here is my take for what its worth

1. it looks quite impressive from an efficiency standpoint,

2. it looks painfully complex to me, and

3. it looks to be quite expensive, but

that seems to be par for the course when it comes to pushing the envelope and fighting for ever
higher efficiencies.

it seems as though high power, high efficiencies, and small size equate to near impossible or crazy
complex and expensive.

its an interesting concept, in that there appears to be no brushes, no slip rings much like an induction generator
or a pm, but without the loss of control which they seem to have covered quite well with the added stator winding
and the power electronics to inject control over the power in the rotor and in turn the power induced back into the stator.

do you have a reference to a commercially available product that uses this technology, so we can take a look at
just how well it works in practice?

all in all, quite interesting, thanks for the link

bob g

[rcavictim]

Funny, I was looking at that patent yesterday and i cannot recall where I saw the link.  Small planet!

I agree with Bob in that it looks pretty complicated with the necessary associated power electronics.

Just in case you guys aren't familiar.  Years ago induction motors with a wound rotating armature and slip rings allowing access to these windings were manufactured and commonly used in industrial applications.  By this I mean not the usual so called 'squirrel cage' armature. If one could find one in a motor junkyard this might be an interesting device to put on the lab bench and play with different excitation ideas.

[mobile_bob]

there is one here in tacoma in a scrap yard, it however has both a three phase stator and a three phase
rotor, so it has three slip rings and associated brushes.

they are known as wound field rotors iirc

bob g

[mkdutchman]

bob,
I was not able to dig up much of anything in the way of a commercially available product like that in the patent. I did look up the patent holder (Satcom Technologies) and they don't seem to be a mfg as much as some type of consulting/services rendered organization.

Also I noticed that the patent was filed in '97 or thereabouts. How long are patents good, is it 20 years?

[rcavictim]

there is one here in tacoma in a scrap yard, it however has both a three phase stator and a three phase
rotor, so it has three slip rings and associated brushes.

they are known as wound field rotors iirc

bob g

Might be worth grabbing Bob!  How big is it?  Voltage?  HP?

BTW, you can use one of these as a sort of Variac.  If you attach a lever control arm that can be locked in place to not move when the motor tries to turn it, you will have a variable coupling transformer for smooth power control of a load!

You can easily add hand control by using a right angle worm gearbox.  That will resist the torque effect of the motor shaft effectively locking it in the desired location whilst allowing an easily turned handwheel position control.

I'd be on that like a pit bull on a raw steak!