Posted by Johnny B Good on October 22, 2008, 12:45 pm
It's a nice idea (and I've, conceptually, toyed with the idea myself),
but it would only really be applicable to a larger micro-hydro power
project where the alternator's output was used directly as an AC supply
and a constant frequency was required.
In this instance, you'd reduce the no load consumption by the field
control circuit and hence the water power demand, conserving what might
be a limited resource and have less overhead from the control circuitry
under peak demand. Overall, a much welcomed improvement of efficiency.
Here, the aim would be to simply compensate for volt drop due to I2R and
other losses in the generator, the speed being entirely regulated by the
amount of water being admitted to the pelton wheel turbine.
In the more typical homepower case, where a battery bank or two is used
to store the energy and smooth out demand on the prime source, a PM
generator represents the optimum solution, in conjunction with a
switching voltage regulator, for most efficient extraction of wind or
hydro power.
Wind powered generators enjoy the most benefit from this technique (PM
alternator feeding a rectifier pack with a switching regulator) where
even just a trickle of power is considered a useful 'top up'.
The water powered case of maintaining a battery supply, where frequency
stability is not an issue, is also best served with a PM alternator.
Here, regulation of the voltage from the rectifier pack is best done by
control of the water consumption (a flywheel on the alternator shaft
helps smooth out speed variations). However, you need to have measures
in place to tame the resulting hydraulic surges any 'rapid response'
metering controls would place on the penstock plumbing.
HTH
--
Regards, John.
Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.
Posted by Vaughn Simon on October 22, 2008, 1:49 pm
> The analog regulator I designed had a bi-polar (H-bridge) architecture that
> could drive the trimmer coil to either polarity. It had to add a little
> magnetism at idle but subtracted some at high speed.
> I ran it in the car long enough to know that it worked great. The regulator
> was tiny and usually had to supply far less than an amp to the field.
Amazing! When do you sleep John?
Since cars are getting to the point where tiny improvements like this applied
fleetwide could make a noticeable difference in CAFE, you would think that this
would be a common item. It would add no weight and save (what?) about 50 watts
on average? In bulk, the additional price of the hybrid alternator along with
its special regulator could be negligible.
Vaughn
Posted by Ulysses on October 20, 2008, 2:05 pm
> >>
> >> ... Your setup, and descriptions, say that you are using an
> >> automobile alternator.
> >> Have you considered a homebrew permanent magnet alternator,
> >> based around the Volvo disc brake setup? It could be more efficient
> >> for what you're doing. It's mainly used for wind generators, but your
> >> setup would apply
> >>
> >> Have you or anyone you've read about built one of those using old car
> >> speaker magnets? I assume hundreds of thousands of "stock" speakers
> >> ge
> > t
> >> thrown away as they are replaced by custom stereo systems and some of
> >> the magnets are pretty hefty. I just wonder if it would be worth the
> >> troub
> > le to
> >> try and scrounge for some rather than spend $150 for magnets.
> >>
> >> "z" is using a PMA. It must be the blocking diode that made you
> >> think
> > it
> >> was a car alternator.
> >
> > It was the photo of the setup that looked like a vehicle alternator
> > was being used.
> > Need strong magnets? Get the two from the magnetron portion of a
> > discarded microwave unit. You see them being thrown away regularly,
> > easy enough to scrounge the magnets.
> >
> It uses the same housing as a GM alternator but its PM from
> www.windbluepower.com
> I started with an old electric motor but it didn't cut the mustard so I
> splashed out on one of those -- once I proved to myself I could make the
> wheel spin :)
Is it a PM DC motor? Got any wind? I'll bet you could make some PVC blades
and put it on a rotating mast in less than 2 hours.
Posted by z on October 21, 2008, 1:29 pm
>
>> :
>>
>> >>
>> >> com ... Your setup, and descriptions, say that you are using an
>> >> automobile alternator.
>> >> Have you considered a homebrew permanent magnet alternator,
>> >> based around the Volvo disc brake setup? It could be more
>> >> efficient for what you're doing. It's mainly used for wind
>> >> generators, but your setup would apply
>> >>
>> >> Have you or anyone you've read about built one of those using old
>> >> car speaker magnets? I assume hundreds of thousands of "stock"
>> >> speakers ge
>> > t
>> >> thrown away as they are replaced by custom stereo systems and some
>> >> of the magnets are pretty hefty. I just wonder if it would be
>> >> worth the troub
>> > le to
>> >> try and scrounge for some rather than spend $150 for magnets.
>> >>
>> >> "z" is using a PMA. It must be the blocking diode that made you
>> >> think
>> > it
>> >> was a car alternator.
>> >
>> > It was the photo of the setup that looked like a vehicle alternator
>> > was being used.
>> > Need strong magnets? Get the two from the magnetron portion of a
>> > discarded microwave unit. You see them being thrown away regularly,
>> > easy enough to scrounge the magnets.
>> >
>>
>> It uses the same housing as a GM alternator but its PM from
>> www.windbluepower.com
>>
>> I started with an old electric motor but it didn't cut the mustard so
>> I splashed out on one of those -- once I proved to myself I could
>> make the wheel spin :)
>
> Is it a PM DC motor? Got any wind? I'll bet you could make some PVC
> blades and put it on a rotating mast in less than 2 hours.
Not much wind here man, or i'd be all over it. I'm in a pretty sheltered
area. The only real wind I get is when a storm hits .. and then its way
too much wind.
I'd have to run around a mile of wire to get to a high ridge that is the
nearest spot .. and no road going up there so ..
Posted by Ulysses on October 21, 2008, 7:18 pm
> >
> >> :
> >>
> >> >>
> >> >> com ... Your setup, and descriptions, say that you are using an
> >> >> automobile alternator.
> >> >> Have you considered a homebrew permanent magnet alternator,
> >> >> based around the Volvo disc brake setup? It could be more
> >> >> efficient for what you're doing. It's mainly used for wind
> >> >> generators, but your setup would apply
> >> >>
> >> >> Have you or anyone you've read about built one of those using old
> >> >> car speaker magnets? I assume hundreds of thousands of "stock"
> >> >> speakers ge
> >> > t
> >> >> thrown away as they are replaced by custom stereo systems and some
> >> >> of the magnets are pretty hefty. I just wonder if it would be
> >> >> worth the troub
> >> > le to
> >> >> try and scrounge for some rather than spend $150 for magnets.
> >> >>
> >> >> "z" is using a PMA. It must be the blocking diode that made you
> >> >> think
> >> > it
> >> >> was a car alternator.
> >> >
> >> > It was the photo of the setup that looked like a vehicle alternator
> >> > was being used.
> >> > Need strong magnets? Get the two from the magnetron portion of a
> >> > discarded microwave unit. You see them being thrown away regularly,
> >> > easy enough to scrounge the magnets.
> >> >
> >>
> >> It uses the same housing as a GM alternator but its PM from
> >> www.windbluepower.com
> >>
> >> I started with an old electric motor but it didn't cut the mustard so
> >> I splashed out on one of those -- once I proved to myself I could
> >> make the wheel spin :)
> >
> > Is it a PM DC motor? Got any wind? I'll bet you could make some PVC
> > blades and put it on a rotating mast in less than 2 hours.
> Not much wind here man, or i'd be all over it. I'm in a pretty sheltered
> area. The only real wind I get is when a storm hits .. and then its way
> too much wind.
> I'd have to run around a mile of wire to get to a high ridge that is the
> nearest spot .. and no road going up there so ..
So just put it on a one mile high pole! ;-)
My experience says if you can get around four volts by turning it by hand at
about one rpm then it should work. Maybe if you use a small two-blade prop
and only get some power from it during storms....
> could drive the trimmer coil to either polarity. It had to add a little
> magnetism at idle but subtracted some at high speed.
> I ran it in the car long enough to know that it worked great. The regulator
> was tiny and usually had to supply far less than an amp to the field.