AC Induction motor or DC motor or Hugh's Design?

[indicjames]

Thanks to the patrons of fieldlines, otherpower, windstuffnow, hugh's site,missouriwindandsolar etc

i have done extensive reading on the above links before starting my hands on wind and solar

but i got into this confusion now,if someone can help me, i would be glad . (Unfortunately, i will be missing the guidance from zubbly after reading the thread http://fieldlines.com/story/2008/4/1/225757/1245)

i have got 2 hp 1750rpm AC motor, now i thought of going in with zubbly's converstion document (7.5hp he did),

magnets   - n38 arc (1" x 1" 1mm thickness)\

AC motor  - 2hp 1750 rpm

remove the armature and try out replacing it with same shape with the places for magnets(zubbly  ) , regarding stator's, does it requires to remove the coils and rewind them ? if so what was the gauge size of magnet wire i need to use?, how many poles, how many turns (10 turns?) ?

since i live in good windy area (7kmph to 12kmph - southern india), i thought of using 10" blades

_james

[opo]

Hi there, welcome to the forum.

One good thing to check is the resistance of each phase or each coil group.

You could start by removing 3-4 mm (measure carefully) from the rotor in a lathe. The motor must be 4 pole. So you'll need to place the magnets around the rotor in a NSNS pattern. How many magnets per pole? that will depend on the rotor diameter and length.

After that you'll need to turn the conversion at known RPMS to get an idea on cut-in speed and then ,if all goes well, test for amps into a battery.

You'll need to rewind it only in case the output of this conversion is outside the range of a direct drive propeller, lets say a cut in between 100-400 RPM.

The slower the cut-in speed the bigger blade diameter it can use. The draw back here will be that you have to make sure you can control the speed of the windmill at high wind speeds and this require power and/or furling.

If the cut in RPM is high you'll need a smaller diameter propeller to reach cut in at a reasonable wind speed.

But knowing RPM for cut in is not the end of the story. In order to match a set of blades you'll need also to perform power in vs power out tests, this will get the most power out of the conversion.

If the cut in RPM is too slow for your intended voltage then you can start playing with the windings by, for example, removing the star point connection of the windings.

etc.

Cheers,

Octavio

[Flux]

I am not sure from your introduction whether you are wanting information on how to do a motor conversion or whether you are comparing your options between a motor conversion, a dc motor or a Hugh type axial air gap alternator.

dc motors are very limited and are mainly small starter projects. Motor conversions are good for decent wind areas and are tough though not always the most efficient. They don't perform as well as the axial machines in low winds.

Your 2 hp motor is 4 pole and you will need to arrange magnets in such a way that you get 4 poles. I assume there is a typo in your magnet size, if they really are only 1mm thick then forget it you need a minimum of about 6mm for arc magnets and thicker for round or rectangular ones.

Many choose a motor conversion rather than have to wind but in most cases you have to reconnect the windings. This can be a confusing process unless your motor happens to be connected exactly as in Zubbly's example. The best results generally are obtained by rewinding, any reconnection is usually a compromise but in some cases it all works out right.

Motor conversions seem to be favoured by those with sound mechanical knowledge and facilities but not so confident with windings. Those with little mechanical facilities tend to go for axial machines, to do a decent motor conversion you at least need a lathe.

Flux

[nicolethomson]

Flux

it is about "how to do a motor conversion"

because i am living in a hilly area, where i can see 12m/s most of the time, many big time wind mill organisation's like suzlon,vestas have established their wind mill in this locality.

"Your 2 hp motor is 4 pole and you will need to arrange magnets in such a way that you get 4 poles". I assume there is a typo in your magnet size, if they really are only 1mm thick then forget it you need a minimum of about 6mm for arc magnets and thicker for round or rectangular ones."

         Have organised 2"x1"x.5" N40 magnets, now for 4 pole how many magnets needs tobe used? the space could be sufficient for 6 or at the max 8. could this be sufficient? i really dont know, how to arrange the magnets to get 4 poles 2 north, 2 south pole?

Octavio

"If the cut in RPM is too slow for your intended voltage then you can start playing with the windings by, for example, removing the star point connection of the windings."

By default the induction motors will be connected with Wye connection? or it will be a mixture of both delta/star?

[indicjames]

Some confusion nicole,

as i mentioned earlier, the magnet size is "n38 arc (1" x 1" 1mm thickness)"

you want me to try N40 2"x1"x.5" in place of this n38?

can i pileup 2 or 4 of above and use them in place 2" magnets?

--James