Build a very low speed DC generator

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Christophe
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Build a very low speed DC generator




by Christophe » 18/06/09, 10:26

As part of my "small" hydraulic paddle wheel project (I put "small" because it is small through the investments and the power but certainly not through the hassles and the time already spent!), I think (I could be wrong?) that for get the best yield (or rather productivity year round), it is necessary to study the possibility of building from A to Z, a custom generator... directly coupled to the drum and therefore low speed!

Indeed, the wheel rotates between 50 and 100 rpm, it has torque but not enough rotational speed to obtain a good generation of current with a wind generator even with a reduction (which also eats a little power as a bonus). In addition it is subject to greater power variations than with a wind turbine ...

So I recovered some interesting documents on the net on this subject and that I will potash (sorry everything is in English):

a) Electromagnetism course applied to generators

Document 1: theory and principle of generators
Document 2: special wind generator


b) Build a permanent magnet wind turbine generator from A to Z

c) Some homemade generators with some interesting comparative curves (tension / speed)

d) A wooden wind turbine (generator included)


The idea is to make a DC generator with permanent magnets, you will understand.

Still to be defined for "start" (all):

a) the number of magnets
b) the number of windings (= a) in theory but?)
c) the number of turns
d) arrangement of coils
... e) in order to obtain roughly 12 or 24 V at ... 50 rpm!

But let's not start the simplest: do you think that this is realistic as a project or that it is a pure waste of time (and money) compared to an industrial generator + coupling?

ps: these docs are from this page http://www.greenenergywindturbine.com/download/vawt/ (thank you Luc)
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by dirk pitt » 18/06/09, 11:41

no secrets, to have sufficient tension at low speed, you will need a large number of poles.
one of your doc talks about the famous use (in australia) of the F&P smart drive washing machine motor.
this engine is very well suited but it still requires more than 50rpm: (rather around 200 to 300)
This engine cannot be found in Europe but there are equivalents.
the direct drive system on LG washing machines
Image

otherwise, the complete manufacture of axial (and not radial) coils cast in the resin is described in many sites such as thereof for example

I think you will not escape a compromise: a reduction to increase the speed by a factor of 3 or 4 followed by a house generator at low speed (200rpm)
also think that the multiplication will allow you to move the generator away from the water : Cheesy:
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by Christophe » 18/06/09, 11:45

Yes for the large number of poles, the diameter of the wheel of the machine's belt (approximately 30 cm in diameter) is doing just fine :)

If I throw myself in it (not on) it is for the most having gear ...

Thanks for the info, I'll see!

If it is to have 200 or 300 rpm as much buy a generator made of wind turbine right?
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by dirk pitt » 18/06/09, 11:59

Christophe wrote:
If it is to have 200 or 300 rpm as much buy a generator made of wind turbine right?


you said "minimum budget" so house construction

I fear that the voltage obtained directly at 50rpm is low but why not.

the other thing I had already thought about, given the small powers, would be to use a boost converter. 3 to 5V input: 12V output

on the other hand I do not really see why absolutely do without multiplication ?? it's not complicated and the power absorbed remains low (surely no more than what will eat in the performance of a very low speed generator)
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by Christophe » 18/06/09, 12:05

Well, minimum budget does not necessarily mean building a house ... with equivalent performance if you know what I mean! The house construction must above all allow to meet a need not present on the market because it can rise quickly more expensive than the purchase of an industrial object.

The voltage at 50 rpm will depend on the number of poles .... In theory, nothing prevents a generator from 12V to 1 RPM ...

After if it is to spend 300 € on copper wires or magnets actually, I prefer to buy a ready made gene ...

For the reduction, it is just that (in addition to the lack of space see photo), even if it means making a custom gene, as much to do without it and fix everything on the wheel on which the crown is fixed:

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by Alain G » 18/06/09, 12:51

Bonjour Christophe

The reduction in chain eats that very little energy or even ridiculous and also allows you to optimize performance.

You can triple your voltage simply by connecting your diode bridges differently and using three large capacitors.

Have you made voltage readings with the latest changes?

If so, give it to us and we could make you an easy diagram.
:D
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by elephant » 18/06/09, 14:34

Finally, when we see a car alternator, it is made up of relatively few large section turns. Why not rewind it (patiently: mrgreen :) in the lower section?
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by the boulle » 18/06/09, 15:48

lut

I am working on a half linear half rotary half which will start producing the first turns ...


I keep you up to date : Lol:
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by Christophe » 18/06/09, 19:15

Alain G wrote:Have you made voltage readings with the latest changes?


Well before the break because of the balour it did not exceed 5-6 V peak precisely :(

I finished fixing the 2nd drum + bearing but I noticed that the 1st drum was ... veiled ... pfff ... a solution brings a new shit ... jti jur not easy !!

I have to put blading and put back in the water. It will be done in the next few days ...

elephant, the problem is the excitement, otherwise we can do the looping method: self-build-and-crafts / alternator self-modify-for-wind turbine-t4674.html but its RPM is still too high ...

I started to cram document 1 and according to the theory it is possible to obtain, at 1 tr / s, a "correct" tension is enough to obtain enough strong magnets and enough turns ... but hey that's the theory ...

The ball, I suggest that we keep ourselves informed :)
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by elephant » 18/06/09, 19:57

Christopher said:

elephant, the problem is the excitement, otherwise we can do the looping method: self-build-and-crafts / alternator self-modify-for-wind turbine-t4674.html but its RPM is still too high ...


Well, you get as excited as you want :D . Normally the basic excitation is in DC and in series, but if you increase your voltage, you can decrease your current, the important thing is the amps all.

So if you have 6 volts now, if you have 40 X more turns, you can have 40 X more voltage and less current.
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