DIR Return Create A Forum - Home
---------------------------------------------------------
Lynx Wind Forum
HTML https://lynxwindforumhtml.createaforum.com
---------------------------------------------------------
*****************************************************
DIR Return to: Electronics related to alternative Energy
*****************************************************
#Post#: 659--------------------------------------------------
Re: NessProjects Boost Circuit
By: nessprojects Date: October 27, 2013, 11:59 am
---------------------------------------------------------
I have just seen what others are seeing in regards to D5 and D6
which can be removed.
Seems the only gain with these diodes is the 0.6v drop through
the others.
one half of the positive will go through D1 and D4, The other
through D2 and D3.
D7 and D8 will still be required to pass the negative cycle.
The caps still hold in that size depends on current required for
low speed.
Hope this helps NP.
#Post#: 661--------------------------------------------------
Re: NessProjects Boost Circuit
By: jeffd Date: October 27, 2013, 2:40 pm
---------------------------------------------------------
CG wanted me to post some of my findings here about the circuit.
I've been using this circuit on one of my small HAWTs since
2009. I too had D5 and D6 in place but was told in 2010 that
they were useless and would never get forward biased to conduct.
I didn't agree but decided to take some measurements of the
working circuit at different input voltages and also setup the
circuit in a Spice simulator. I was really surprised to see it
for myself. You will not see it when there is no current flow
in the simulation or when there is not battery hooked up on the
output.
I found that D1 and D3 would conduct at the same time on one
half the cycle and then D2 and D4 on the opposite. About half
the current flows through D1 charging C2 and the other half
through D3 to the battery. The current in the stator was always
double the current to the battery.
I did eventually get D5 and D6 to conduct but input AC voltage
had to be way above battery voltage and it was dependant on the
values of C1 and C2. At 100uF D5 and D6 would start conducting
at around 19VAC input. But for my little HAWT that would be
around 12 m/s wind speed. If the caps were around 400uF then D5
and D6 would not start conducting until around 40VAC input.
Those two diodes did not relieve the load on the doubler. Over
2/3 of the total current into the battery was still going
through the doubler.
So I guess it really depends on the turbine and what you use for
C1 and C2 that will determine if you need D5 and D6. There is
no harm in having them there ie if you used a full bridge
rectifier module. In my case I was using individual Schottky
diodes so ended up taking those two out since they would never
conduct when used with my little 50W turbine.
I'm not an electronics engineer, just a hobbiest so I might have
misinterpreted whats going on. If you have something like
LTSpice its fairly easy to setup the circuit and simulate. Put
some current probes between components and see what happens.
The same can be done with a scope and current probe on the real
circuit.
Anyway, regardless of whats going on, the circuit is a quick and
cheap way to get the turbine to produce some power at low wind
speeds. Hate to see a turbine spinning and not feeding power to
the battery bank.
#Post#: 662--------------------------------------------------
Re: NessProjects Boost Circuit
By: jeffd Date: October 27, 2013, 3:05 pm
---------------------------------------------------------
I blew a few caps when I first started using the circuit but it
did take a few months before they blew. The first time it
occurred was in Oct 2009 during a tropical storm. It has to do
with the ESR value of the cap. I was pumping 500 mA AC current
through the caps that were only rated for an AC ripple current
of 30 mA and had an ESR of 16 ohms below 1000Hz. The heat
boiled the electrolyte in the cap and popped the top. I bought
some low ESR caps and have never had a problem since.
The other solution could have been to put a number of caps in
parallel to reduce the equivalent series resistance.
#Post#: 663--------------------------------------------------
Re: NessProjects Boost Circuit
By: nessprojects Date: October 27, 2013, 3:10 pm
---------------------------------------------------------
Hi to jeffd
Spent all afternoon simulating this circuit using CIRCUIT WIZARD
and I found it was using D5 and D6 once 10vac input was reached
and did relieve the amp draw on the doubler.
Simulators, Can we trust them ????
I too am just into electronics as a hobby.
As you say its the real world tests that count.
Thanks for your input, Regards NP
#Post#: 664--------------------------------------------------
Re: NessProjects Boost Circuit
By: lynx wind Date: October 27, 2013, 3:36 pm
---------------------------------------------------------
Great conversation.
Here's my two cents. I like simple, and the circuit
Nessprojects is showing is that and it works. It might be a
good learning tool/stepping stone for people who aren't ready
for big PCB layouts.
The other thing is, I hope some of you start experimenting with
these single phase alternators and Gull type VAWTs. I think you
will see that the VAWT has no problems racing up to match the
watts in the wind without need for a boost.
If wind is at 5mph and you can't fly a kite, there is almost no
wattage to harvest anyway. So really you should be aiming for
an efficient alternator in the 10-20 mph range. Efficiency is
going to fall off at +30 mph which occurs rarely anyway.
If someone built an alternator/turbine that doesn't reach cutin
until 12 mph then I think a boost would be perfect to cutin at
say 7-10mph and then let the main rectifier takeover.
Fun stuff!
#Post#: 665--------------------------------------------------
Re: NessProjects Boost Circuit
By: nessprojects Date: October 27, 2013, 3:47 pm
---------------------------------------------------------
Building a Vawt pretty much as your DIY version now but using 21
awg wire.
We have had 40+mph for the last 2 days !! and nearly always get
80+mph during winter months so I do need a good shutdown system.
All the best NP
#Post#: 672--------------------------------------------------
Re: NessProjects Boost Circuit
By: nessprojects Date: October 28, 2013, 4:23 pm
---------------------------------------------------------
@ CG
Northwest Coast of Scotland, I can see the Atlantic from the
kitchen window so nothing to stop my turbine from gaining speed
from the west !!. Houses are built to survive.....Vawts... well
we will see. ::) ::)
#Post#: 688--------------------------------------------------
Re: NessProjects Boost Circuit
By: nessprojects Date: October 29, 2013, 6:12 pm
---------------------------------------------------------
If I had that kind of money kicking around I don't think I would
be playing with 50w turbines. HA HA ;D
#Post#: 711--------------------------------------------------
Re: NessProjects Boost Circuit
By: barbados Date: November 1, 2013, 3:29 am
---------------------------------------------------------
Hi NessProjects,
Very good circuit.
What value diode are used D1-D4.
Are they standard diodes or schottky diodes?
Many thanks
Andre
#Post#: 714--------------------------------------------------
Re: NessProjects Boost Circuit
By: francisco Date: November 1, 2013, 11:35 am
---------------------------------------------------------
Hi, do you happen to have the pcb drawing for this ? ( I know
that maybe I'm asking to much :) )
regards
Francisco, from sunny Portugal
*****************************************************
DIR Next Page