DIR Return Create A Forum - Home
---------------------------------------------------------
Lynx Wind Forum
HTML https://lynxwindforumhtml.createaforum.com
---------------------------------------------------------
*****************************************************
DIR Return to: Electronics related to alternative Energy
*****************************************************
#Post#: 3814--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 10, 2014, 9:57 am
---------------------------------------------------------
Thanks,
It should be ok, because the little red led isn't blowing and
the gate likes 2-4 volts. I'll give it a try. The current
power transistor is working but the frequency is about 250hz
#Post#: 3817--------------------------------------------------
Re: Buck Boost Idea
By: nessprojects Date: July 10, 2014, 5:30 pm
---------------------------------------------------------
@lynx
Run the rene circuit in the simulator and changed over to
mosfets...tried tweaking but just could not get it to
oscillate....Not sure why.
With my rene circuit instead of putting a led in the base I
wound about 2 or 3 turns around the toroid and connected a led
to that (check led in both directions and adjust number of
turns). This gave a good indication of maximum field in toroid +
it proved it was oscillating but this was from a fixed
transformer.
Not sure why but I have been trying to get on this site for
nearly a hour....It just sits with a blank page....Strange
!....Not the first time either....maybe creataforum site is
getting overloaded.
#Post#: 3820--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 10, 2014, 7:03 pm
---------------------------------------------------------
Ness,
Your simulator is darn good. That is exactly what happened. No
oscillation, just straight through the mosfet. The power
transistor did oscillate just not very fast. maybe 250 hz max.
#Post#: 3877--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 16, 2014, 7:36 pm
---------------------------------------------------------
Good experimenting.
The problem with wind turbines is the voltage is dependent on
speed. If we want the turbine to run up past stall we have to
let it go from low to high voltage. But most storage of power
is done at a constant voltage (battery or grid) most loads are
designed for certain voltages, like lights, heating elements
etc...
If we pulse high voltages to a storage like a battery - that
works. But the duration of the pulse has to be controlled by
something that knows the power in the wind for the size turbine.
If we try to use the turbine itself, we compound the problem
because as we take power we change the signal.
I hate complexity but something like an anemometer attached to
the pole could signal the square wave pulse. A hall effect
transistor in an anemometer could be used to signal.
Faster square wave frequency x higher voltage = higher watts
Slower square wave frequency x lower voltage = lower watts
#Post#: 3878--------------------------------------------------
Re: Buck Boost Idea
By: nessprojects Date: July 16, 2014, 8:28 pm
---------------------------------------------------------
Been fooling around with this circuit as a kind of booster that
regulates the output on its own....It has not been tested in the
real world but the simulator seems to think that L1 can be
anything (Larger the better).
The lower the incoming voltage the sharper the pulses. It seems
to charge L1 and once charged it starts the dump process
regardless of the input voltage.
Depending on the setting of the 100k pot it can drop way down to
about 2v input or so it seems !!.
It is not tested in any way by myself in the real world !!!
.....I hold no responsibility for blown components should you
try this. :)
#Post#: 3881--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 17, 2014, 7:45 am
---------------------------------------------------------
Ness and CG,
I know people commonly struggle with low voltage output and want
to boost. But, really the better way to do this is design a
fast turning VAWT and a high voltage alt. If we have high
voltage from a higher resistance stator we don't have to have
high amps. Resistance in the stator is the enemy of power
output. For instance it is much better to develop 60 volts at 3
amps in an alternator rather than 18 volts at 10 amps.
I=V/R Amps = volts/resistance 3=60/20 vs 10=18/1.8
So using a buck circuit to adjust the voltage down to the load
voltage we don't have to worry as much about the stator R. Now
if we design a low resistance stator that is turned by a fast
VAWT that is even better.
#Post#: 3883--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 17, 2014, 8:46 am
---------------------------------------------------------
I understand. We are talking about two different things. I am
talking about a Turbine in a good wind location. What you are
doing is good for a low wind location. in your case you want as
big a swept area as you can tolerate. But it needs to built
strong enough to handle the occasional squall.
Something to consider with the capacitor. It's like a battery.
It's not like a bucket. Lets say the VAWT is putting out peaks
of 16 volts. The cap will slowly charge up to those peaks. It
wont keep going higher with time. So however you set your
circuit to cycle it wont do anything if the voltage doesn't come
up to the trigger point. If you set the trigger point low to
capture the little bit of power in 5mph winds, there needs to be
some way to capture the power in the 15 mph winds too, which is
about 12x higher.
#Post#: 3884--------------------------------------------------
Re: Buck Boost Idea
By: nessprojects Date: July 17, 2014, 9:24 am
---------------------------------------------------------
Well I was getting really confused about this topic but now I
understand where this is going.
It is much better to have high voltage from the turbine, better
for the wire run too but not given much thought on using a buck
to drop the voltage and raise the current. I think really you
are heading into mppt territory.
How about a high voltage turbine feeding a transformer at the
battery location, maybe a small circuit to stop the transformer
working until the turbine has reached a certain voltage/rpm ?.
I remember that a very crude mppt can be made from multiple taps
from a transformer, something to think about.
#Post#: 3885--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 17, 2014, 9:42 am
---------------------------------------------------------
You got it. I think putting a boost into the front end of the
Buck was confusing. (It can work though)
The problem with a transformer is it is a dead short, or it has
to be high resistance. MPPT isn't something I can do or want to
do. It's beyond me. I am hoping we can leapfrog MPPT and come
up with a simple and elegant solution.
Keep thinking and experimenting guys.
#Post#: 3900--------------------------------------------------
Re: Buck Boost Idea
By: lynx wind Date: July 18, 2014, 1:38 pm
---------------------------------------------------------
Thanks for working on this.
Make sure the cap is not too big. Otherwise the rpm of the VAWT
may stall as it starts up the voltage curve. Ideally the
adjustment would be set low in low winds and higher in high
winds. In high winds it would be great if the voltage could
race up to say 60-70 volts and dump in spurts (square wave) to
the load.
*****************************************************
DIR Next Page