Posted by BobG on September 26, 2005, 8:01 pm
There are some interesting build it yourself sites describing hefty
permanent magnet 3 phase alternators for windmills. Just wondering if
it would be feasible to run the generated AC from the coils thru a
voltage step up transformer, run the high volt/low current 3 phase down
the tower and into the barn or wherever where it can be rectified and
used/stored/inverted etc. Mainly wondering about range of freq of
generated AC, size of transformer needed. Crazy idea, or am I onto
something here?
Posted by Anthony Matonak on September 26, 2005, 8:57 pm
BobG wrote:
> There are some interesting build it yourself sites describing hefty
> permanent magnet 3 phase alternators for windmills. Just wondering if
> it would be feasible to run the generated AC from the coils thru a
> voltage step up transformer, run the high volt/low current 3 phase down
> the tower and into the barn or wherever where it can be rectified and
> used/stored/inverted etc. Mainly wondering about range of freq of
> generated AC, size of transformer needed. Crazy idea, or am I onto
> something here?
If you build the alternator on the windmill so it can charge your
batteries directly then you lose less energy in converting from
one voltage to another. If you did want to do this kind of thing
then you would want the windmill to produce as high a voltage as
you're comfortable with and then use a step down transformer and
rectifier at the batteries. I believe some commercial turbines
work in this exact fashion.
By the way, you don't have to build the turbine as a 3 phase.
You can built it as a single phase alternator without losing much
in the way of efficiency. The picoturbine units are all single
phase, for example.
Anthony
Posted by Solar Flare on September 26, 2005, 9:28 pm
Three phase, when full wave rectified, needs no filtering whereas single
phase needs filtering to be able to transform it up or down for battery
charging efficiently.
BobG wrote:
> There are some interesting build it yourself sites describing hefty
> permanent magnet 3 phase alternators for windmills. Just wondering if
> it would be feasible to run the generated AC from the coils thru a
> voltage step up transformer, run the high volt/low current 3 phase down
> the tower and into the barn or wherever where it can be rectified and
> used/stored/inverted etc. Mainly wondering about range of freq of
> generated AC, size of transformer needed. Crazy idea, or am I onto
> something here?
If you build the alternator on the windmill so it can charge your
batteries directly then you lose less energy in converting from
one voltage to another. If you did want to do this kind of thing
then you would want the windmill to produce as high a voltage as
you're comfortable with and then use a step down transformer and
rectifier at the batteries. I believe some commercial turbines
work in this exact fashion.
By the way, you don't have to build the turbine as a 3 phase.
You can built it as a single phase alternator without losing much
in the way of efficiency. The picoturbine units are all single
phase, for example.
Anthony
Posted by BobG on September 26, 2005, 9:40 pm
AM:
If you build the alternator on the windmill so it can charge your
batteries directly then you lose less energy in converting from
one voltage to another.
================================================
I think having a very effcient switching converter between the
alternator and the batteries would be a more controllable situation...
the battery load varies due to charge state, etc, and the generated
voltage and current varies according to wind state! The converter could
load the alternator as lightly or as heavily as needed to take
advantage of light wind conditions, etc. Transformers are 99%
efficient, so I'm not too worried about losing energy converting from
one voltage to another in the transformer... just wondering about the
frequency! Whats the blade RPM? The number of coils around the
alternator determined the elec freq. An aircraft type 400HZ transformer
might be just the thing to step up the coils to something that could
make a run down the tower without a lot of I-R drop.
Posted by Solar Flare on September 26, 2005, 10:08 pm
The RPM varies a lot from model to model and the frequency varies with the
RPM and the number of poles.
AM:
If you build the alternator on the windmill so it can charge your
batteries directly then you lose less energy in converting from
one voltage to another.
================================================
I think having a very effcient switching converter between the
alternator and the batteries would be a more controllable situation...
the battery load varies due to charge state, etc, and the generated
voltage and current varies according to wind state! The converter could
load the alternator as lightly or as heavily as needed to take
advantage of light wind conditions, etc. Transformers are 99%
efficient, so I'm not too worried about losing energy converting from
one voltage to another in the transformer... just wondering about the
frequency! Whats the blade RPM? The number of coils around the
alternator determined the elec freq. An aircraft type 400HZ transformer
might be just the thing to step up the coils to something that could
make a run down the tower without a lot of I-R drop.
XML site map
> permanent magnet 3 phase alternators for windmills. Just wondering if
> it would be feasible to run the generated AC from the coils thru a
> voltage step up transformer, run the high volt/low current 3 phase down
> the tower and into the barn or wherever where it can be rectified and
> used/stored/inverted etc. Mainly wondering about range of freq of
> generated AC, size of transformer needed. Crazy idea, or am I onto
> something here?