Iron core PMA construction

[Sam Chamas]

Hi there,
i just want to share this PMA project with you.
it will be intersting to some of you.
http://www.youtube.com/watch?v=l6vFatalNRc&noredirect=1

best regards
sam chamas:idea:

[Rob Beckers]

Hi Sam,

Good to see you're building alternators! After watching the video I'm left scratching my head as to what you are trying to show. Is the point that turns equals voltage on a stator? So, half the turns is half the voltage? That's no news. Possibly I'm missing something?

-RoB-

[Sam Chamas]

Hi Sam,

Good to see you're building alternators! After watching the video I'm left scratching my head as to what you are trying to show. Is the point that turns equals voltage on a stator? So, half the turns is half the voltage? That's no news. Possibly I'm missing something?

-RoB-

hi there Rob,
i was showing the convetional coil VS the Serpentine coil using the same turns, rpm, core and load.
the result showed that the serpen will produce the same wattage at double the rpm but less wattage input consumption.

sam

[Rob Beckers]

Sam, got it. I found another video explaining the serpentine winding concept, that made things a bit clearer. The part I don't understand yet is why a serpentine coil works at all, since there are no windings that actually enclose magnetic flux. Guess I have to get my EM-field book out and dust it off...

I'm not sure that measuring the losses by looking at the power it takes to drive the alternator is valid: What you are also measuring is the efficiency of the motor driving the alternator, which may be very different at various RPMs. Alternator losses would be largely a matter of resistance of the windings vs. current (I^2 * R), and eddy-current losses if you have iron in the core.

-RoB-

[Chris Olson]

The part I don't understand yet is why a serpentine coil works at all, since there are no windings that actually enclose magnetic flux.

You don't need windings that enclose flux. All you need to do is put a single straight wire between two points and alternate pass N-S over the wire and you will induce a voltage in it.

A coil is simple method to put more wires in the path of the changing flux to get more voltage. The serpentine winding is yet another method.

The conclusion that a serpentine winding is "superior" somehow is flawed. There is no advantage either way because it still boils down to ohm's law and how many lines of flux are cut with the winding.
--
Chris

[Sam Chamas]

You don't need windings that enclose flux. All you need to do is put a single straight wire between two points and alternate pass N-S over the wire and you will induce a voltage in it.

A coil is simple method to put more wires in the path of the changing flux to get more voltage. The serpentine winding is yet another method.

The conclusion that a serpentine winding is "superior" somehow is flawed. There is no advantage either way because it still boils down to ohm's law and how many lines of flux are cut with the winding.
--
Chris

You are correct Chris, the sience is clear.
you did help me back in 2010, i was working on my first axial flux, i am dabling in anything that spins. The serpen coil seamed easier to wind.

regards
sam:bigsmile:

[Chris Olson]

Yes it is easier to wind and put together because it doesn't require as much soldering. Ed Lenz has used them in his educational kit turbines for years. I've wound a few with serpentine windings - both axial and radial generators - and typically I can get slightly lower internal resistance at the same rpm/volt with a soldered up "conventional" coil layout.
--
Chris