Hi All :)
This little escapade started when i bounced about a few ideas for alternative alternator designs.
see; http://www.fieldlines.com/story/2004/5/31/3145/27921
Here's the basic concept (f.1)
And the magnetic flux lines seen with magnetic viewing film (f.2)
The results for the intial test rig are here;
http://www.fieldlines.com/story/2004/6/4/81857/45538
Seen end on, this is the full layout (f.3)
I reinforcend the rotors with glass fibre strands and superglue.
And built a second test rig. (f.4)
This rig uses a Lego 9v Technic Motor - older 3000 rpm type
To run the motor for the test rig, I used wind-up power :)
see; http://www.fieldlines.com/story/2004/5/26/15451/3307
The chain of events goes like this...
I turn the handle on the wind-up genny making electricity, the DC output runs the motor on the test rig, the rotor spins and the coil gives out AC...
Visualisation and theory are all well and good, practice is more fun :)
Image f.4 above shows the stator, with a single coil of 11 turns 20SWG wire, approx 1m length.
Not expecting much out of such a small coil, I set up the meters.
The motor on the test rig is designed for 3000 rpm @ 9v DC, my wind up genny can put out 38v...
...I wound up the genny...
Genny output, 21v DC (approx 3000 rpm)
Lego motor/rotor speed, 6500 rpm
Single 11 turn 20SWG coil output...
Max AC open voltage = 0.45v @ ~7500 rpm
...AC short circuit...
rotor approx 5000rpm, AC 0.2v at 2.89 Amps, 0.578 watts :)
Single 25 turn 24SWG (2.4m wire length) coil output...
Max AC open voltage = 1.2v @ ~7500 rpm
...AC short circuit...
rotor approx 5000rpm, AC 0.5v at 1.3 Amps, 0.65 watts 8)
Single 50 turn 28SWG coil output...
Max AC open voltage = 2v AC @ ~7500 rpm
...AC short circuit...
rotor approx 5000rpm, AC 0.075v at 1A, 0.075 watts :(
With the second coil, I also tested the output with a piece of steel on the outside of the stator, volts to rpm remained about the same for more input torque (seemingly less efficient... tho Amps weren't recorded)
All wired and no place to go.
For the stator in the image above, I used 20SWG wire, winding the 'coils' in situ. Each phase uses 4m length wire, there are 3 on the stator. Each 'leg' is 9 strands, 36 legs in all, equivalent to 6 coils of 9 turns to each phase.
Somewhere along the line, I must have wound the 2nd phase wrong, or it shorted.
Open AC voltages at 6000 rpm 1st phase = 1.2v, 2nd phase = 0.7v, 3rd phase = 1.2v
I tested short circuit amps across phase 1, the rotor about 3000 rpm, 1.49A.
All attempts at 3 phase testing were depressing due to the 2nd phase probs :(
Bits of the stator former broke as well :(
On the up side, I was getting Power out of the coils...
Is it compareable to conventional rotor performance?
With a larger diameter rotor/stator there would be more space to wrap the coils over the edge of the magnet, maybe increasing the output.
...so...
With the 50 or so 1"(l) x 1/4"(w) x 1/4"(h) neo blocks I've got, I should be able to make a couple of 6" or a 12" rotor :)
The fun is waiting to get out... somehow 8))
paul
