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would it be possible design any psu without any electrolytic capacitors?
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aqarwaen:
I just wonder how hard and how much it would cost design any psu without any electrolytic  capacitors?lets say psu is any 750w and don't use any electrolytic fluid capacitors.would it possible to design any psu what used and capacitors instead electrolytic fluid capacitors?
angrybird:
This is a wonderful topic to get some seasoned power supply guys arguing over  :-DD

What power supply architecture are you considering?  What is your input/output voltage?  Is it fixed output voltage?  Do you have specific transient response or fault tolerance requirements?  Any objections to a high frequency design?  Depending on architecture, are you capable of winding your own magnetics?
Circlotron:
For an AC mains fed PSU, if you are going to use capacitors of relatively small value you are not going to be able to keep the voltage from falling to near zero when the AC mains crosses zero. Unless of course you can tolerate a battleship size iron core inductor in there somewhere.

One solution might be to use a 3-phase full wave rectified source because the voltage never falls to zero.

dmills:
Three phase input makes it easy to drop the bus cap as long as power factor is not too much of an issue.

If you really want smooth DC on the bus, go with the old 12 pulse rectifier technique, needs a star-delta transformer of rather weird ratio, but does work.

The low voltage output caps are possibly harder, so some kind of highly polyphase design might be indicated to get the required total value down far enough. Could be that voltage mode (spit!) would actually be easier here for all that it makes basically EVERYTHING else worse.

Got to admit, I don't really get the hate on for elcos, a good quality part derated suitably for temperature and ripple will go a good 20 years or so if you derate with that intention in mind, just got to do the sums and them make sure purchasing don't screw you over.
twospoons:
Well, the simple answer is "yes", with the caveat that it would be more expensive and physically larger than a PSU built using electrolytics.
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