Model multi pole Generator plans?

[JorgensenSteam]

They use to use generators on automobiles, but they did not put out much voltage at low rpm, so they changed to alternators.

Both type devices move energized coils of wire or magnets past other coils of wire, inducing a current.

The current is the same, however, the generator has a commutator (the banded looking thing on the shaft) which reverses the polarity as the generator revolves, thus producing a voltage that does not change polarity (DC = direct current).

An alternate does not have a commutator, but only needs two slip rings, and produces alternating current and voltage that changes polarity as the alternator rotates. Direct current is produced by passing the alternating current through a bridge rectifier circuit, which has the mechanical analogy of a check valve.

Here is a nifty Cretors I ran across at a local Electrical Contractors office a few weeks ago.
If you push the button, an air compressor comes on, the engine runs, and the generator powers the street lights.

I told them I need to come over and take some measurements.

 

[///]

Technically, an alternator is still classed as a generator.
Alternator = AC generator
Dynamo = DC generator

 

[steamer]

Hi Dave,
I see the words like Generator and Alternator tossed around. I am talking about the ones in HD for the home residence. and so. What is the difference between the two or are the booth the same? Did You ever had to use the one at Home?
Hilmar?

Hi Hilmar

Yes I have had to use one at home. ...and technically It's an alternator
And Yes I am using them interchangably...and perhaps not correctly...appologies
Thanks /// for the explaination....I tend to ( that is TEND) to follow the verbage on the left side of your argument....but then again I'm a Mechanical Engineer..... :

Dave

 

[steamer]

Technically, what I'm researching is a permanent magnet AC alternator. The reason I'm looking at this is because it doesn't need commutation, or slip rings.

Slip rings are used on automotive alternators to supply power to the rotor coil...the rotor is the part that spins. In it is a coil of wire so wound that when current is supplied, it generates a magnetic field, North on one end and South on the other.

This magnetic field, North and South are conducted through two multi lobed claw rotors with what look like interwoven fingers. As a result of this construction, the fingers have alternating north and south poles.

Varying the magnetic intensity (flux) of these poles will control the output of your car's alternator. Now you know what the voltage regulartor on your car does....varies the input to the rotor windings to provide a constant output as you don't want your lights getting brighter or darker depending on how fast your engine is turning

For the application I have in mind...direct drive from a steam engine model, I am less concerned about a steady voltage. To simplify the system, I am working this design study to use a permanent magnet for the rotor in place of the coil of wire on the automotive rotor....no slip rings required and no commutation.

A consequence of this is that the voltage will vary as a function of speed of rotation....but for a small demonstrator IMHO..I think that is a good thing.

I'm considering a "claw pole" rotor because it's pretty easy to make, can be machined externally to a simple disc shape which , visually, looks in keeping with the old time "generators", and it gives me some leeway to change magnets around in the rotor to change performance....IE it lets me adjust. To do that , the rotor halves are split and an axially disposed ring magnet(s) are changed, added or subtracted, as required. Most of the designs I've seen thus far include gluing magnets to rotors and such which seems a pain, and pretty permanent!

I think based on some of the articles I've read, a laminated stator is not really required for this application.....as I'm not trying to make a performance specification, just light up a few lights to amaze the kids and the kids at heart.

One article I read , for the stator poles, the author dragged a magnet around the yard and picked up all the magnetic sand (magnetite?) in the yard, mixed it with epoxy and cast the "pole" pieces in place!....the article attached in my previous post shows a alternator with no pole pieces whatsoever.....just coils.

I'm thinking this can be pretty simple..

Here's some inspiration

[ame]http://www.youtube.com/watch?v=eQteZyjTwmQ[/ame]

The pulley on the far end is to run a field generator....not needed on the model

Here's a model made by Jerry Howell
http://craftsmanshipmuseum.com/images/How ST H10.jpg

Dave

 

[steamer]

Here's the other article I mentioned.

http://www.angelfire.com/ak5/energy21/magnetitecoregenerator.htm

Dave

 

[///]

Oops, sorry Dave if you thought I was correcting you.
I was answering Hilmar's question.
Probably should have addressed him to avoid the confusion.

I have been trying to find a nice donor stator to turn into an armature for a dynamo. Harder than I thought it would be.
Found a couple that looked perfect(number of poles/diameter/thickness) at Hobbyking, but they are out of stock
Found another one that I have ordered, not quite what I wanted, but will experiment with that.

Simon

 

[steamer]

Oh no worries ....Simon.... no offense taken or implied....good to get the terminology right.

Cheers!

Dave

 

[John Rudd]

Take a look at this link...http://www.reuk.co.uk/DIY-2kW-Wind-Turbine.htm]

Here it describes how to make a 2kw wind powered generator...

How about building something on a smaller scale? Would make a small compact alternator with no need for slip rings...

Need magnets?...try here: http://www.supermagnete.de/eng/index.php or
http://www.supermagnetman.net/

 

[steamer]

Yes John, that was my point exactly.
Though I would rather not make an axial unit.
Dave