DC/DC Converter

D

Dupont

Guest
Gentlemen,

I am starting the design of a DC/DC converter used as a Wind turbine
battery-charging system.

The DC wind turbine output voltage will be connected to the input of the
Controller.
The output of the controller will be connected to a lead-acid 24 Volts
battery bank, 1440 Ah capacity.

The basic data of the wind turbine output are:

At low Low speed: 35 volts 1 amp
At High speed : 156 Volts 13 amps

What kind of DC/DC Step-down topology (Buck, Push-Pull) is the most
suitable:

- Buck classic
- Buck synchronous
- Several Buck in parallel
- Multiphase Buck
- Push Pull topology

How can I deal with the very large input voltage, because I found no PWM
controller.
The closest I found is the LINEAR LTC 3703 that can work up to 100 Volts.

Is there any PWM controller else ?

Thanks four your help
A.
 
On Mon, 14 Feb 2005 21:40:15 +0100, Dupont wrote:

Gentlemen,

I am starting the design of a DC/DC converter used as a Wind turbine
battery-charging system.

The DC wind turbine output voltage will be connected to the input of the
Controller.
The output of the controller will be connected to a lead-acid 24 Volts
battery bank, 1440 Ah capacity.

The basic data of the wind turbine output are:

At low Low speed: 35 volts 1 amp
At High speed : 156 Volts 13 amps
Click to expand...
It'd be cheaper and more effective to rewind the generator to give you a
more constant voltage over a wider current range. Look into
automotive-type alternators and their regulator circuits. They seem to
manage a constant voltage at a pretty wide range of RPMS and have decent
current output.

Good Luck!
Rich
 
John Popelish wrote...
Dupont wrote:

Gentlemen,

I am starting the design of a DC/DC converter used as a Wind turbine
battery-charging system. The DC wind turbine output voltage will
be connected to the input of the Controller. The output will be
connected to a lead-acid 24 Volts battery bank, 1440 Ah capacity.

The basic data of the wind turbine output are:
At low Low speed: 35 volts 1 amp
At High speed: 156 Volts 13 amps

You will need a couple hefty inductors and switches to make a current
controlled two phase buck regulator.
Click to expand...
I'll say! This is a 35 to 156V range, or a nearly 5x voltage range
and 35W to 2kW, which is a 60x power range. These are not easy
parameters for a simple buck converter, or whatever. I wonder if
any of the commercial wind-generator converters work effectively and
efficiently over this full range. What's more, one cannot regulate
output voltage, current or power, per se, because these should all
be variable, as a complex function of wind speed. If one attempts
to regulate any one of these, the generator could be loaded to the
point of stall and a poor wind-power collection would result.


--
Thanks,
- Win
 
There are a lot of COTS DC-DC converters with 4:1 input range up to
100s of watts. Buy one of these and try it. Then get another one and
hook two in parallel when the wind is really blowin.
 
Many thanks to all of you.

Bob, if I follow your recommendation, does it mean that I can connect two or
more buck converters in parallel ?
Do I need to add a diode after each of them before joining the outputs ?
Your solution seems very interesting because of the modular architecture.
Does it makes sense to look for clock synchronization of each individual
unit if the final load is a battery bank ?

Best Regards
Al
 
"Dupont" <dupont@hotmail.com> ha scritto:

Bob, if I follow your recommendation, does it mean that I can connect two or
more buck converters in parallel ?
Do I need to add a diode after each of them before joining the outputs ?
Click to expand...
I don't think it is so easy the parallelizing of SMPS: a diode will not
be enough.
According to me for a correct current sharing you will need a
complicated current control loop that tries to eliminate the current
unbalancing between converters.

--
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