>> If we plan on making a toothed wheel with inductive pickup
part of
>> the design then the flywheel style alternator will need to go
onto the
>> opposite end of the shaft. The magnetic field of the alternator
will
>> interfere with the timing pickup. It looks like Renesis has the
>> toothed wheel behind the pulley.
>> The DIY wind power generators I have seen are very close
and are
>> called "axial flux"
>> The coils are turned were they look like a bunch of 'O's
making
>> petals to a flower.
>>
>> The places for the axial flux alternator:
>> Prop flange
>> prop rpm
>> part of the split PSU and still in design phase
>> moment is large
>> between the planet cage and fly wheel
>> engine rpm
>> part of the split PSU and still in design phase
>> moment is large - ~16"
>> Pulley side
>> Move toothed wheel to flywheel - minimal moment
change
>> Could be part of an accessory case design
>> moment
>>
>> --
>> Blake C. Lewis
>>
>>
>> What do you do about the eddy currents in the aluminum? There
is heat
>> and resistance to power in this housing. I ask because I have
designed
>> motors with aluminum housings. A proff of this power is to
place a
>> plate of aluminum on a series of "toothpicks" for bearings or
"wheels".
>> Rapidly pass a neodymium magnet over it and the aluminum will
move. In
>> a motor or generator that energy develops heat and drag. Does
this
>> design address that?
>>
>> Rick Irwin
>
>
> Rick,
> I haven't designed electric motors before. I am assuming
that you
> are referring to the moving magnets as opposed to a moving stator.
> A prop flange design would be a way to minimize this problem,
being
> that location has the least amount of stationary metal.
> I think that the RevMaster and the Harley radial designs
both have
> aluminum housings.
> How significant do you think that the heat and drag is in the
> efficiency of the alternator over a conventional automotive
design? Do
> you think that the loss is more or less than that due to belt
loading
> and friction?
>
> --
> Blake C. Lewis
The magnetic flux will be contained in the iron cores of the coils.
Eddy currents in the non-ferrous frame will not be an issue. With
this
type alternator there may be some efficiency issues with the voltage
regulator, however. These alternators are usually paired with a
shunt
type regulator. With this type regulator the alternator is producing
near full output all the time. With a 30 amp alternator that
would be
about 360 watts (about 1/2 horsepower net). There may also be
mechanical losses because we will probably need to incorporate a
fan in
the structure somewhere to cool the coils and the voltage
regulator will
need to be located in a cool air stream. The Compu-Fire system
that was
mentioned last week is unique because the Compu-Fire regulator is a
series-pass type which would save a little energy when the aircraft
electrical load was low.
Aubrey
I believe that modern regulators for pm alternators are all series
pass... The one that is used on the BandC dynamo is
(http://www.bandspecialties.com). I have this unit on my O-200 Varieze,
and it works great. The regulator doesn't seem to get very hot (though
it's only producing 12A).
I think the newer motorcycle dynamos are 3phase..
Matt-
Matt,
That is a nifty little unit. The B & C link above has apparently
changed. I found the alternator here, however:
http://www.bandcspecialty.com
I noticed the capacitor and twisted-pair wiring in the wiring diagram.
This may be a switched mode regulator that is very efficient (and
capable of more than 12 amps). We should keep it mind for possible use
with another PM alternator.
Aubrey
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2005 All world wide rights reserved.