Not much of a builder myself, but, I think in a hydro [24/7] situation it would be hard to beat an induction motor conversion. A good one has 100% duty cycle bearings and is likely to have about the right windings for Mains level power if you get the right speed. Some even come from the factory built for wet conditions and most are pretty well sealed to start.

Just my thoughts.

Sir Zubbly could give you pointers on spotting good candidates as well as how to do it.

Cheers.

TomW

A motor conversion would look like the ticket to me. Here's a story of a 3 hp I have converted; in star, it needs 6 RPM/v, so that translates to 250 Vac at 1500 RPM (we have 50 Hz over here).

Here's the story:

http://www.fieldlines.com/story/2006/12/17/22270/167

And here are more pics of the conversion and some technical details:

http://www.anotherpower.com/gallery/3HP-induction-conversion

Feel free to use any drawings, specs etc. freely. Nothing is under contract, -everything- is out in the public domain and fully and freely available to each and everyone...

Personally I would fully rely on -properly- glued in magnets. Even without using glue, they shouldn't fly off the rotor at 3000 RPM (calculated it once, for a rotor moving in free air (i.e. not turning inside a stator). A bit of proper glue (epoxy) should provide more than enough to keep them in their place on the rotor.

If you need more information, don't contact me privately but ask in here.

www.smallhydropower.com/induction.htm

I am quite well aware of the Induction Motor as a generator since I have used them
for many decades.

I am interested in knowing those that have converted a regular induction motor rotor to a magnet rotor, specially those that have used magnets with holes to mount them to the rotor and magnets that are curved for such arrangement.

If I remember right some were reported some time back.

The reason for a brushless permanent magnet generator is multiple.

a) As an independent generator.
b) As a master generator to attach an induction motor ( as induction generator) to it to have a much greater power generator, where the PM generator represents around 10 % of the total power that can be generated.

Plus other cases.

i can tell you of the 2 7.5hp induction generators i have done.

the first one was made from a 7.5hp 3 phase 4 pole motor, high eff, manufactured by HICO. HICO did much of the building for westinghouse in korea, and finally took over the production of the units under the HICO name (basically a westinghouse motor-all parts interchangable). i rewound the stator to 12 pole, turned down the rotor and installed 4 round 1 inch diam x 1/2 inch thick N35 mags per pole (48 total) and skewed.
the unit produced 4700 watt at 600 rpm 60HZ connected to a set of heating elements. voltage at 600 rpm unloaded was 242 volt 3 phase. under the 4700 watt load the voltage dropped to 190 volt. the load was held for 20 minutes with no heating of the gen at all. the testing was stopped after 20 minutes as the 5hp baldor DC motor that was belt driving it started tripping the overloads. the unit was sold, but has not been flown as a gen to my knowledge.

the second one is the unit i am presently flying. i used it to help suplement heating in my home this winter connected to a 3 phase heating bank installed in my oil fired furnace. i have since found i can capture more power from it connected to a 60 volt battery bank and dumping to the elements once the batts are charged.  was just too much power wasted waiting for the gen to hit 100 volt (when the contactor pulled in to the elements) on less windy days. the unit was made from a Baldor 7.5hp single phase motor. i rewound the stator to 12 pole, installed a solid steel rotor with machined flats, and installed 2 of the 2x1x 1/2 inch mags with the tapered holes per pole (24 mags total). i think the mags were N40 or N42. unloaded voltage at 600 rpm 60 HZ is 240 volt 3 phase. i have seen a little over 4kw at approx 450 rpm with this unit. the prop is 12 foot diam 3 blade. the blades however are a 2 blade profile.

here is the link on the construction of the rotor. http://www.fieldlines.com/story/2006/6/16/202945/707

if you look at my postings, you will find the postings on the winding of the stator and the other postings of getting the unit flying.

just a tip when looking for a donor stator.  many (but not all) of the newer high eff motors in the T-frame class, have much larger stator slots in comparison to the older T-frame design. older design had approx 350 cir mill of copper per ampere and many of the newer units now have 800 plus cir mill of copper per ampere.  the larger slots allow you to pack much more copper into the winding.

just a personal note Nando, i don't think you have to go as high as 1500 or 3000 rpm to get some good kw rating.  i suggest using larger motors and keep the rpm down with as many poles as possible from the winding.  i still intend to convert my 25hp Baldor. it will be 16 pole and have a total of 48 of the 2x1x 1/2 mags. i expect an easy 5 or 6 kw at low rpm.