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Wind Generator with Hard Drive Magnets | 44 comments (44 topical, 0 editorial)
Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#19)
by mrkooo (mrkooo@hotmail.com) on Fri Sep 30th, 2005 at 09:53:21 PM MST
(User Info)

Finally I cast the stator, I forgot to use wax, had problems to get it off the mold, but it'ok.

Now is installed with the rotors, when I spin it with my hands I have 7.2 per phase. I thinking to wired it in star configuration, how much volts you think I will get with 3 rectified phases. Its ok to connect it in star or delta with this volts per phas. I want to char a 12V battery. One phase has 4ohms.









Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#20)
by ghurd on Sat Oct 1st, 2005 at 02:04:08 AM MST
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I am surprised with the 7.2V.  Good work!

Have you considered rectifying each phase seperately?  
Like 3 single phase generators in one stator.
I have a feeling with 4 ohms per phase, and 7.2V at low RPMs, it could work out much better.

I also have a feeling the blades might be too long. Shorter blades of the same design will run faster.

Only 16 (Only 16!) more hard drives will give enough magnets to increase the output, stacking them 3 thick on both rotors.  Or 8 hard drives and place all the additionial magnets on the same rotor.  The air gap to magnet ratio will be better.

G-

[ Parent ]



Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#21)
by mrkooo (mrkooo@hotmail.com) on Sat Oct 1st, 2005 at 07:03:02 PM MST
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What is the differences between connecting it in star than seerately each phase. What advantages and disadvantages.
I think that maybe more V if after rectifying the 3 DC I connect it in series than if I connect it in star. And what about the amps?

Thanks
Francisco


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Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#22)
by electrondady1 on Sun Oct 2nd, 2005 at 07:34:07 AM MST
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 hello and congratulations mr.koo.
i have had good luck. in another town, i got 8 more harddrives from the computor stores there .
 some harddrives contain only one magnet which is double thickness. i intend to use these magnets as the default thickness.others will need to be dubble to match.

gurd, i asked this question in hikers post. what about a coil for each pole (single phase) but three layers thick,= three phase?

[ Parent ]



Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#23)
by mrkooo (mrkooo@hotmail.com) on Sun Oct 2nd, 2005 at 08:49:42 AM MST
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elctrondady, how you are planing to make the alternator, breaking the magntes in two pieces or with the 2 poles per face.

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#24)
by electrondady1 on Sun Oct 2nd, 2005 at 09:30:50 PM MST
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  its more work, but if i cut them up i will have more control over the size and shape of the coil. i like long coils

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#25)
by electrondady1 on Sun Oct 2nd, 2005 at 10:20:11 PM MST
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one thing i noticed, there seems to be a lot of different thicknesses ,  

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#27)
by ghurd on Mon Oct 3rd, 2005 at 08:28:50 AM MST
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The 3 layer thick stator. Look around here for overlapping coils, or a 12/36 arrangement, and look at windstuffnow Ed's 18/27 "Alt from scratch".  Better suited for a single-rotor, or maybe with real thick magnets, due to too much material at the top and bottom of the coils.
Also have a look at Ed's old post '3 phase vs. 3 phases' it might be called.
I have a single rotor 6/9 or 8/12 about half done. High hopes. Too busy to get more done for a while.
Just finished last years taxes(!) last night. 2 extensions, No kidding.
G-

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#26)
by ghurd on Mon Oct 3rd, 2005 at 08:13:17 AM MST
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I had a couple projects with too high resistance, too many coil turns, and too low cut in speed.
They worked better rectified seperatly, like 3 seperate single phase generators in 1 stator.  Normaly it is not the best idea.
G-

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#28)
by electrondady1 on Tue Oct 4th, 2005 at 07:26:30 AM MST
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the last two i built were disapointing as well, but they were both experiments so i won't let that stop me .  i learned alot !

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#29)
by finnsawyer on Tue Oct 4th, 2005 at 08:33:56 AM MST
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When he mentions rectifying each phase separately I think he means running each phase through a diode (rectifier) to a capacitor to set up the output voltage for that winding.  The three outputs are then stacked or added to form the output voltage to the battery.  This should get you the maximum voltage possible for a given alternator rpm.  We recently went through a discussion of the merits of such an approach.  Check my recent comments to track it down and find a schematic for the circuit.  Just keep in mind that there are no single answers in electronic design.  You have to tailor the design to fit your needs.
GeoM
[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#30)
by electrondady1 on Tue Oct 4th, 2005 at 02:44:04 PM MST
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hello fin, how you doing? i think i follow gurds method. instead of going star or delta  he's turning the output of each phase into dc and then combining them , i'll try to find the post you describe. am i right in thinking the dc can be combined in paralel or series?

[ Parent ]


Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#33)
by finnsawyer on Wed Oct 5th, 2005 at 10:12:05 AM MST
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Yeah, you can combine dc voltages in series at will if they are floating (neither one is connected to system ground - well one can be).  Parallel, no, as you can get nasty circulating currents if there is a slight imbalance in their values.  But one can work around that by adding resistors to the circuit.  Anyway ,here's the schematic:


The capacitors are necessary for proper operation. Without them you will have the three phases adding, which gives zero voltage at all times.  System ground would normally be at the bottom.  The resistor represents the load.  Without the capacitors the mid connections go nowhere.  I feel it's important for people to understand that the dc voltage has to appear across something in order for it to be stacked with another, so I dug up the schematic.  Sorry about the size.  I'm beginning to think that this stuff should be put in a FAQ for easy reference.
GeoM
[ Parent ]



Re: Wind Generator with Hard Drive Magnets (3.00 / 0) (#34)
by ghurd on Wed Oct 5th, 2005 at 10:31:48 AM MST
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Yes. Each phase full wave rectified. Then paralleled to the battery.

Just sounds to me like, was it 7.2V(?), at low speed by hand, combined with 4 ohms per phase, that if it was wired in star it might be a better at higher voltages than 12V.  I could be way off, it's all based on reverse enginering of my failures.

G-

[ Parent ]



Wind Generator with Hard Drive Magnets | 44 comments (44 topical, 0 editorial)

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