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wide range DC to 13.8V DC converter

C

chris

Jan 1, 1970
0
Hi,

I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.

The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

A long winded way would be to convert the input to a simple square
wave, and pass it through one of set of transformers, which is
automaticaly selected based on the input voltage. So T1 could deal
with voltages 20-30V, T2 30-50V, T3 50-80V... Then rectify and
regulate the output to 13.8V. As I say, long winded! And there has to
be a better way!

Ideas?
 
J

John Larkin

Jan 1, 1970
0
Hi,

I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.

The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

A long winded way would be to convert the input to a simple square
wave, and pass it through one of set of transformers, which is
automaticaly selected based on the input voltage. So T1 could deal
with voltages 20-30V, T2 30-50V, T3 50-80V... Then rectify and
regulate the output to 13.8V. As I say, long winded! And there has to
be a better way!

Ideas?

You need a buck switching regulator, which would convert available
power to battery charging power at ballpark 90% efficiency.

How much power (in watts) does the turbine generate? How much current
can the battery stand?

There may be a standard module available that does what you want.
Vicor? It's not exactly a beginner's project to design a good,
efficient, wide-range, current-limited buck switcher.

John
 
P

PeterD

Jan 1, 1970
0
Hi,

I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.

The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

A long winded way would be to convert the input to a simple square
wave, and pass it through one of set of transformers, which is
automaticaly selected based on the input voltage. So T1 could deal
with voltages 20-30V, T2 30-50V, T3 50-80V... Then rectify and
regulate the output to 13.8V. As I say, long winded! And there has to
be a better way!

Ideas?

Switching regulator?
 
J

Jon Slaughter

Jan 1, 1970
0
chris said:
Hi,

I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.

The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

A long winded way would be to convert the input to a simple square
wave, and pass it through one of set of transformers, which is
automaticaly selected based on the input voltage. So T1 could deal
with voltages 20-30V, T2 30-50V, T3 50-80V... Then rectify and
regulate the output to 13.8V. As I say, long winded! And there has to
be a better way!

Ideas?

How much current can the turbine output? or whats its power rating?
 
D

David Lesher

Jan 1, 1970
0
chris said:
I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.
The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

meci.com had a bunch of DC-DC convertors....
 
N

Nobody

Jan 1, 1970
0
I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.

The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

A long winded way would be to convert the input to a simple square
wave, and pass it through one of set of transformers, which is
automaticaly selected based on the input voltage. So T1 could deal
with voltages 20-30V, T2 30-50V, T3 50-80V... Then rectify and
regulate the output to 13.8V. As I say, long winded! And there has to
be a better way!

Buck converter.

http://en.wikipedia.org/wiki/Buck_converter

Assuming that the current/power are relatively low (otherwise the
shunt resistor approach wouldn't be realistic), and you don't need
particularly high efficiency (it couldn't be any worse than a shunt
resistor), this isn't that hard.

You can get dedicated chips which will do most of the work (search for
"switching regulator"), but at low power you could probably get away with
just using an op-amp wired as an inverting comparator with some
hysteresis: if the output voltage is too low, turn the switch on, if it's
too high, turn it off.
 
C

chris

Jan 1, 1970
0
Thanks for the info.

The turbine is rated at 100W, and can deliver around 8A. But I would
rather over-spec anything I connect to it as in high winds it may
output more.

If modules are available, I could presumably connect several in
parallel to achieve the current handling?
 
F

foobar

Jan 1, 1970
0
Hi,

I am trying to figure out how I can make a regulator for a small wind
turbine. The output is to charge 12V lead acid batteries.

The turbine outputs from 0-110V - (usually around 20-30V). The normal
approach is to regulate to 13.8V, and dump the excess voltage through
a shunt resistor. However this seems very wasteful, and I was
wondering if there is a way of converting the excess voltage to
current?

A long winded way would be to convert the input to a simple square
wave, and pass it through one of set of transformers, which is
automaticaly selected based on the input voltage. So T1 could deal
with voltages 20-30V, T2 30-50V, T3 50-80V... Then rectify and
regulate the output to 13.8V. As I say, long winded! And there has to
be a better way!

Ideas?

I have thought about this problem before.

It is a complex load matching problem. The electrical load that the
turbine feels will directly effect the mechanical resistance of the
turbine. But for any given wind speed there is an optimal rotation speed
to deliver max power. That is, as the wind speed goes up, you can ratchet
up the resistance on the turbine. But if you ratchet it up to high, too
soon, the turbine will enter into an inefficient aerodynamic region, and
no longer deliver loads of power.

Furthermore, depending on the state of the battery, there is a max
power it can accept (going down to near zero when the battery is fully
charged). In case the turbine is delivering more electrical power than the
battery can accept, you need to dump that power into some kind of heating
device (resistor or transistor load).

If you have something that works already, and was designed by
professionals, I would not try to improve on it.

--Mac
 
J

JosephKK

Jan 1, 1970
0
chris [email protected] posted to sci.electronics.design:
Thanks for the info.

The turbine is rated at 100W, and can deliver around 8A. But I would
rather over-spec anything I connect to it as in high winds it may
output more.

If modules are available, I could presumably connect several in
parallel to achieve the current handling?

Probably not, unless they were specified to do that.
 
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