dc to dc buck converter ??

Thread Starter

mobile_bob

Joined Aug 13, 2007
6
hello all, new guy here and this is my first post:

i am faced with a project which is a dc to dc converter, of the buck mode version.

first the parameters

i want to feed the converter with 120 vdc of moderate amperage or say 20 amps.

i want to take the output of the converter to charge a battery bank of either 12 volts or possibly 24, either of which will be large flooded cells of around a 1000amp/hrs for the 12volt or around half that for the 24 volt bank.

because this is a learning or experimental project i will be using salvage components most of which i have no idea the values of, such as large inductors.

however i will purchase needed components such as mosfets, and a microcontroller to do the triggering so to speak, pwm or somesuch.

so my question is, where do i find some decent schematics for such a buck converter,, i would like around 120amps at 24 or twice that for a 12 volt system.

any help or direction would be most appreciated
thanks

bob g
 

mrmeval

Joined Jun 30, 2006
833
You can get such convertors or build them but the higher the amperage the higher th cost and the rise in cost is not linear. You can look up details on systems to store collected solar energy as your system sounds similar.
 

Thread Starter

mobile_bob

Joined Aug 13, 2007
6
thanks for the info will check it out

i didn't expect the larger units to scale linearly
i figure that is why i see so many designs with multiple or ganged mosfets as drivers.

anyone have a link to some high current solar buck controllers ?

bob g
 

John Luciani

Joined Apr 3, 2007
477
hello all, new guy here and this is my first post:

so my question is, where do i find some decent schematics for such a buck converter,, i would like around 120amps at 24 or twice that for a 12 volt system.

/QUOTE]

A 2880W DC-DC convert (12V * 240 A) is not a beginners project. If your conversion
is 80% efficient you need 3600W in. You have to design cooling to remove the heat
generated by the 720W of loss. If you are working off a rectified AC line you should
look into power factor correction.

If you need that much power you should look at the DC-DC converters at
www.vicr.com. Take a look at the MegaPACs.

(* jcl *)
 

Thread Starter

mobile_bob

Joined Aug 13, 2007
6
guys:

i don't expect this to be a beginners project, or do i think it will be cheap.

what i have to compare to is the outback mx60 mppt charge controller
at 60amps output max and a price tag of over 600 bucks retail, i figure i have some leg room to work in.

granted outback has all the bells and whistles, but they also have one flaw
which to my thinking is unacceptible.

i don't need mppt, i don't need all the bells and whistles, what i do need is higher amperage and decent efficiency

at 240amps i would need 4 outbacks and a rack to mount them, cost approaching 3 grand with tax.

i have to believe i can build what i want for less than a third of that, and have something that i can understand and repair myself.

i can come up with heavy inductors, capacitors etc surplus, and i figure i can gang the mosfets just as every other manufacture does, perhaps i need a butt load more of them :)

why not?

anyone here work with high capacity buck converters?

bob g
 

bertus

Joined Apr 5, 2008
20,538
Hello,

Do you realize that the thread is from august 2007.
The OP will be gone long.
This is more than 1 year ago.

Bertus
 
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