Author Topic: alternators f or a newbie (Read 2694 times)

wyliang312 · « **on:** November 12, 2008, 01:22:58 AM »

Hello

I notice a lot of people making their own alternators for wind turbines. I am new to this field and want to try building an alternator. I was wondering what equations are being used and, in general, how to being. I want a logical approach that makes me understand everything not just go onto a website and get materials and build one. I would like to know how each step and part affects each other

Please send me some equations on how to start.

Spaz · « **Reply #1 on:** November 11, 2008, 07:39:24 PM »

Well I'm not very good with equations so I can't help you there, but I think someone with a little disipline and mechanical skills one can easly grasp the basics here. Just start by reading! Theres a ton of info here. If you want to learn about wind start in the wind section of Forcefield. Your wind genny will be uniquely yours wether you build it from scratch or do a motor conversion that will be up to you. No one will build it for you unless there getting paid. You have to learn to walk before you run. My first wind mill is more or less a lawn ornament but we learn from mistakes and move on.But if you have any specific questions many here will be happy to help you so read, read, read.

wyliang312 · « **Reply #2 on:** November 11, 2008, 07:49:03 PM »

I guess I should be more specific. I was wondering how to determine the amount of windings, how big of a magnet is etc. I've read a lot of the posts and saw what was created but not sure how the numbers came to be or why they chose that part. so it would be nice if someone said "start off with __ and then from that you know to__" so any starters would be nice! thanks a lot

zeusmorg · « **Reply #3 on:** November 12, 2008, 01:02:38 AM »

The first thing you should know are what the average wind speed in your area is.

This will help you determine what you can get out of a windmill.

One good place to start is the FAQ section, some people have put together some good and useful information there.

Also it is pretty easy to do searches for specific questions.

Once you have started to familiarize yourself with some of the things associated with building your own, if you have any questions, then feel free to ask! If the questions are well though out and enough information is given, there are a lot of people willing to help you.

Also there are some good books and other informative things available from our hosts, at reasonable prices! Reading them will definitely save frustration. (see our products)

TheCasualTraveler · « **Reply #4 on:** November 12, 2008, 04:49:08 AM »

Try this

http://www.otherpower.com/bottom_line.shtml

spinningmagnets · « **Reply #5 on:** November 12, 2008, 08:25:05 AM »

Welcome wyliang312. I haven't built a wind-gen yet, but...

I feel the two biggest questions are, what kind of wind do you have at your site (as previously stated) and also what are you going to do with the power you get?

In order to use off-the-shelf components (such as charge controllers and inverters) most use a common system voltage of either 12-volts, 24V, or 48V. They charge a battery pack, and use an inverter to convert it to the 120VAC that TV's and other appliances use.

I can feel the frustration of an enthusiast who checks the internet for the average wind speed and frequency in their region, then builds a wind-gen to that spec. After raising it he may find that the wind on his particular site is actually much poorer.

You may have many trees, you may be inbetween hills, you may only be allowed to have a short pole by local ordinances and wind is much better the higher you mount it.

Find out how high a pole you can have, and then mount an anemometer up there to begin data-logging. Buying strong magnets to get the best power output is expensive, and a custom PMA is time-consuming and involved (only to find you have to re-do it!).

The benefit of building a custom PMA is that the resulting wind-gen will extract the best possible amount of power from your wind. I think converting a garbogen or ECM motor into a generator looks like a good starter project (Use "Google search the board" and save links you like in a file)

http://www.fieldlines.com/story/2005/4/13/33217/7314

"...Hi ghurd, These PVC blades are perfect for the GE ECM motor. I'm flying 4 GE ECM motor conversions with this blade its a real good match.

I see around 250 watts out of the ECM at 30 mph. Seeing over 100 watts at 15 mph.

This is the the 1-hp unit with my coil reassignments. Also have 36 5amp diodes on this conversion. This conversion was covered in a post a while back.

Not bad for a motor pulled out of a dumpster and a hand full of 25 cent diodes, 3 $15 blades and the rest made from junk..."

wyliang312 · « **Reply #6 on:** November 12, 2008, 11:05:09 AM »

Hello

Thank you very much for your replies. Currently I am only interested in the alternator and not the turbine but if i do plan on making a turbine, i will be a bit more prepared. If anyone has hints on how to design the alternator, feel free to comment but anything is appreciated. As I said before, thank you very much

Flux · « **Reply #7 on:** November 12, 2008, 11:15:11 AM »

You can't really design an alternator without having the end use in mind.

For wind power the design is so closely linked to the wind requirements that you must have the input details.

Alternators for most other applications will have restrictions on speed voltage frequency efficiency and regulation that you will need to know before even having any chance of starting.

In the present world of throw away technology where you buy everything for pence I find it odd that everyone wants to become electrical machine designers over night.

Flux

ghurd · « **Reply #8 on:** November 12, 2008, 11:33:27 AM »

If you have absolutely no design parameters for the alternator, how can we help?

Everything is a ratio.

Bigger magnets or higher flux is more voltage per turn per RPM.

Thicker wire is more amps per coil. More turns per coil is more volts, but less amps.

More magnets per pole, or more RPM, is more of above.

It's easy to build an alternator. Just need some magnets and wire.

It doesn't get a bit complex until the alternator must fit some specific requirements.

Skippy the hamster made power.

http://www.otherpower.com/hamster.html

Wood 103 did too.

http://www.otherpower.com/woodmill.html

Formula are related to the design. And it's purpose for existence.

You are asking for every and all the formula that = X.

We don't even know what "X" is.

G-

wyliang312 · « **Reply #9 on:** November 12, 2008, 12:37:35 PM »

So far I know I will be using an electro magnet.. I would like about 200 rpms which means 32 poles. The alternator will be three phase type. I also am trying to use faraday's law to determine how strong the magnets should be.

V= number of windings (tesla of magnet area of magnet)/(seconds per turn)

The voltage is set, the number of turns is easy to determine since i have the rpms, the number of windings is adjustable and then the magnet is the last issue.

The only problem is that i may have made a mistake with this equation... not too sure if it is accurate.

Currently i am trying to derive an equation to determine the current output if i know the magnetic field of the magnet or some other characteristics. not too sure about this right now...

from this, i will know how much i have to turn the alternator in order to get x amount of current and y voltage.

spinningmagnets · « **Reply #10 on:** November 12, 2008, 01:45:13 PM »

a PMA is a "Permanent Magnet Alternator". The copper wire coils are in the STAtionary STAtor. Since permanent magnets require no electrical input, they are attached to the ROTating ROTor to make construction simple.

"...So far I know I will be using an electro magnet..."

This sounds like the way car alternators work. The spinning armature is a set of electromagnets, and the strength of the magnet is controlled by how much power if fed into them by a Voltage Regulator (VR).

When a car battery is low, the VR sends a lot of power to the armature to make the magnets strong, which increases the power coming out of the stationary field coils. When the battery is near full, the VR cuts back on the power to the armature which makes the magnets weaker, and this lowers the power coming out of the field coils.

The power to the spinning armature is fed to them through spinning on/off switches called brushes and slip rings (which wear out).

You could get this style of alternator to work, but you would be putting more time, effort, and money into a project that would produce less power (the armature magnets "use" some of the field coils output power)

In a constant RPM application, like micro-hydro, or a diesel-gen, you might convert an induction motor into a generator by adding capacitors to provide start-up voltage to the armature electro-magnets, but...

For wind, I can't think of anyone who doesn't use permanent magnets. The most common complaint is trying to get some power from low wind and slow RPMs. An induction generator (with electro-magnets on the armature) must have a certain amount of RPM's before it will make any useful power.

Because of their extra complexity and poor low-wind performance, induction generators are not popular here. Just letting you know ahead of time...

ghurd · « **Reply #11 on:** November 12, 2008, 03:44:35 PM »

In other words, there is NO magnet???

However the voltage is set, 200RPM means 32 poles, and you have the RPMs?

But you only want to know magnetic field or some other characteristics?

All you told us was 200RPM and 32 poles.

I no longer care what the question was,

The answer is "7". The answer is always 7.

My daughter is 19, ask her the square root of eleventeen, and she shouts "7!" from habbit. Because the answer is always "7".

Alternative answers for her are 'pi' and 'John Browning invented it'.

Those won't count in this case.

If you do not believe the answer is "7", produce the rest of this alternator and someone will prove the answer is "7".

"The only problem is that i may have made a mistake with this equation".

With the 200 RPM and 32 poles we have to work with, I think the math you have is dead on accurate.

Nobody could argue with 200RPM and 32 poles!

"7" is the answer.

This is sounding completely OU.

ghurd · « **Reply #12 on:** November 12, 2008, 03:54:12 PM »

If you already have the Tesla - Faraday - Maxwell - etc equasions,

why ask?

The OU thing isn't working out with the prototypes?

(yea- thats just a rant)

kurt · « **Reply #13 on:** November 12, 2008, 06:50:58 PM »

wyliang312, if ghurd is right and you are trying to make some sort of overunity device then go find yourself a overunity board to ask your questions this is not the place for you. overunity discussion is not allowed here. if you are not building an overunity device then be forthcoming and tell us about your project.

Kurt (editor)

TheCasualTraveler · « **Reply #14 on:** November 12, 2008, 08:45:25 PM »

""Currently I am only interested in the alternator and not the turbine ""

""I would like about 200 rpms which means 32 poles. ""

I smell VAWT

wyliang312 · « **Reply #15 on:** November 13, 2008, 01:09:15 PM »

Sorry if i offended anyone with my questions. Honestly, i don't know anything about this field and have only started thinking about alternators (and found out what one was) two days ago. as for the over unity device, i don't know what one is. my only objective was to put out a question and have you guys guide me to build something, almost like what that person built (wood 103). As for having more information, i've been reading what you guys sent out as replies and google-ing to find out more, which lead me to more specs. the equation turns out was wrong. the derivation was flawed. I did find out what a VAWT is and decided that it will be for a VAWT

. I won't be posting any more because I don't want to offend people and I fear I ignorance in this field may have came off shady. sorry again.

ghurd · « **Reply #16 on:** November 14, 2008, 10:39:11 AM »

Looking at it bass ackwards?

The magnet is a fixed quantity. Unless you want it custom made. Look at a list of magnets available. Pick one at least 3/16" thick.

Run the math for the turns to get the voltage (that you never mentioned).

Run the math on the ohms in the coil.

Run the losses at the peak amps (that you never mentioned).

Adjust the magnet size.

The Dans 10' cut in at about 200RPM if I recall.

Windstuffnow Ed made a lot of different things.

Might find a design similar to what you paln, then work backwards from their data.

That's what I do. Works better than you would expect.

G-

wyliang312 · « **Reply #17 on:** November 14, 2008, 10:53:02 AM »

thank you very much. this was exactly what i needed! as for amperage and voltage, i don't know. i have to do more research on the VAWTS to see what can come out of it and what is feasible to build. lots of reading to do and still trying to solve the maxwell's equation so i can do the calculations. it'll take a LONG while.

wyliang312 · « **Reply #18 on:** November 14, 2008, 11:10:34 AM »

I have a question, you mentioned "adjust the magnet size" after you calculate the maxed current loss, I thought the magnet was a fixed thing. Also what is a Dan?

ghurd · « **Reply #19 on:** November 14, 2008, 11:47:57 AM »

You "don't know" the voltage, amps, and therefore output power expected.

You are starting in the middle and working to the end, and you don't know where the end is either. Figuring out the beginning is going to be harder than this part.

Tiny wire has huge resistance. Resistance is lost power. If the magnet you picked needs 2500 turns per coil, then all (almost all) the power made is lost before it gets out of the coils. You need a bigger magnet.

Pick a bigger magnet and start again.

But if you don't know what you want out, then the math won't help.

"The Dans" own this place, wherever here is. DanB and DanF pay good money to make this forum operate. They hope to recover their costs by selling magnets, wire, etc. when the design is finished.

I heard through the grapevine that sometimes Dixie has to give them a loan to throw TomW a bone.

"http://www.otherpower.com/">http://www.otherpower.com/ http://www.forcefieldmagnets.com/catalog/

It would be worth reading everything at otherpower. The basic questions are answered. The questions you don't yet know you have are answered. G-

ghurd · « **Reply #20 on:** November 14, 2008, 11:49:13 AM »

And I have no idea why that tiny stuff happens.

G-

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Author Topic: alternators f or a newbie (Read 2694 times)