Re: gEDA-user: Calculating a linear self excited induction generator

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Sun, Jun 11, 2006 at 02:40:32PM -0700, Samuel A. Falvo II wrote:
> On 6/11/06, Karel Kulhavy <clock@xxxxxxxxxxxxx> wrote:
> >I read about self excited induction generator, homopolar generators,
> >liquid metal dynamos, interstellar plasma dynamos, linear motors
> >and electric meters.
> 
> Ummm . . . Interstellar?!
> 
> >I got an idea of placing two coils almost touching the aluminium rim and
> >wiring them somehow obscurely with capacitors (how people do in wind
> >power plants with squirrel cage motors nobly relabeled as "self excited
> >induction generators") so they would prime themselves and start
> >generating. If it works with cyclic asynchronous motor it should work
> >with a linear one too, shouldn't?
> 
> In what way is it self-priming?  Given a large enough, flat plate

The generated voltage creates eddy currents in the squirrel cage, which
creates magnetism in the squirrel cage, which induces voltage into the
coils.

> dynamo, I'm sure one could exploit the Earth's natural magnetic field.
> But, a small dynamo the size of which is suitable for a bike would
> never have sufficient surface area for electrical generation, no
> matter how fast it's made to spin.

No it's not supposed to use Earth magnetic field.

> 
> Remember that energy is neither created nor destroyed -- if it's
> self-generating, it has to draw energy from somewhere.  Traditional
> alternators draw this energy from shaft rotation.  Where is the
> self-excited generator drawing its energy from?

>From the wheel rotation.

> 
> >1) Reproduce the electricity meter configuration with externally driven
> >2 coils from relays, one 90deg after the other (the wheel should turn).
> >This is how trains and roller coasters with linear motors work so I
> >guess it should work.
> 
> This is basically a coarse-grained stepper motor as I currently
> understand the configuration.

No stepper motor has fine structure on the magnetic circuit. This
doesn't have any structure, just straight rim.

> 
> >2) Drive the wheel manually and see on a scope if the contraption really
> >generates more energy than it eats
> 
> It will never do so.  If it *looks* like it is, it's because it's
> drawing energy from multiple sources.  Remember, with the laws of
> thermodynamics, you can't even break even -- you always lose.

Law of thermodynamics doesn't forbid you braking the wheel and
generating electricity from that.

CL<
> 
> -- 
> Samuel A. Falvo II
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