"James Sweet" wrote in message
news
RJkh.5859$6f4.5807@trndny08...
I'm working on a generator for someone that recently just quit
producing electricity. On the label it touted the fact that it's a
brushless alternator; this is actually the first time I'd worked on
one but I was expecting much more inside it, certainly some sort of
regulator module but in fact it seems the only parts are a stator very
much like that of a large induction motor, a simple 2 pole armature
with a diode mounted to a heatsink, and a capacitor connected to two
of the leads from the stator. The capacitor is open circuit so that's
an obvious problem, diode checks out fine as do the windings so I'm
assuming replacing the cap will get it going.
What I'm curious though is how exactly does this thing work? The
armature has no connection at all to anything. I imagine it must
receive power through induction but how is the output regulated? Is
there a trick to manufacturing these? Given there's no brushes or slip
rings I'd have thought all alternators would be made this way unless
there was a disadvantage.
James,
This is one brushless 3-stage method - there are others.
1st stage. - pilot exiter
rotor = permanent magnet
stator = static coils
Rotate the rotor and AC power is induced in stator coils.
Output from stator coils is fed to second stage within the
stator.
2nd stage. - main exciter
stator = coils fed from 1st stage
rotor = coils
Output from 1st stage stator is rectified and fed to second
stage stator coils - regulation can be imposed here.
Rotate 2nd stage coils in 2nd stage magnetic field
- AC power is produced in rotor and output is fed to 3rd stage.
3rd stage. - output
rotor = coils fed from 2nd stage.
stator = coils
Output from 2nd stage rotor is rectified within the rotor body
and fed to 3rd stage rotor coils.
Rotating electromagnets cause induction of output in 3rd stage
stator coils
--
Regards,
C R Briggs.
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