Electronics > Projects, Designs, and Technical Stuff
1kW 200/400V dc/dc converter design tip
Amper:
--- Quote ---You mention using a ‘transistor’ instead. MOSFETs, IGBTs and BJTs are all types of transistor.
--- End quote ---
In case you meant me, i said bipolar transistor and thats referring to ordinary old school bjt, not fet, no igbt, not even darlington.
The point i wanted to make is that for this task you really dont need insane frequencies, power densities and ultra modern parts at all. They used low tech even for the time and the iron core inductor was only a 50mm toroid including winding.
webgiorgio:
I haven't found an inductor, I have to look in the bin of old large salvaged inductors.
Online I keep getting common mode Toroidal chokes (with two windings in opposite direction) like this one.
https://www.elfa.se/en/toroidal-choke-mh-10-wuerth-elektronik-744834101/p/11064067
https://uk.rs-online.com/web/p/leaded-inductors/8711385/
I guess that they are suited to be used with near zero flux, so I can't simply connect the two windings in series.
--- Quote ---I hanven't look up a transistor, which was suggested as more efficient than a mosfet. Can it be?
--- End quote ---
When I say "transistor" I mean BJT.
@Amper Very nice video! The small one gives an idea on how my converter will look like.
--- Quote from: jbb on January 28, 2019, 04:28:41 am ---For improved efficiency at light load you could consider using a burst mode.
--- End quote ---
What is a simple way to do this?
A second 555 timer with duty cycle dependent on converter current, to enable/disable the PWM of the first 100 kHz 555? (too rough?)
Is a IC available to do this?
richard.cs:
Another topology to consider; a half bridge driving a 1:1 isolation transformer, the output from the transformer is full wave rectified and placed in series with the input supply.
Key features:
Converter only handles half the output power so 500 W
Square wave output so minimal output capacitance is needed
Two switches and two capacitors on the input
Four diodes on the output, you could reduce this to two by going centre tapped but would probably push the copper losses up
Thoughts?
fourtytwo42:
I think there is a safety aspect here that does not seem to have been considered in this thread. The GTI you name IS NOT ISOLATED meaning the PV side is at GRID POTENTIAL moreover the GTI does not have arc sensing meaning there can be a fire hazard on the PV side. Both these issues make it unsuitable for DIY electronics additions to the PV side.
As an alternative had you thought of extending the existing string, are the new panels on the same roof face, if so you can add them as long as N*VOC <=700V.
Another alternative would be to use a separate GTI for the new panels as GTI's are quite happy to operate in tandem (on the GRID side) or replace your existing GTI with something more suited to your combination of panels.
coppercone2:
Are there any available tantalum caps on the market that would make that gigantic lump of foil capacitors go away?
Why are hermatic ones only built to 100v?.
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