Alex555 wrote:I will have two of them switched alternately. The idea is to make two outputs isolated from each other, bot necessarily from the input.I am putting the two isolated outputs in series for a positive and negative supply. I can build an oscillator straight off of the input with enough delay to account for the turn off times being longer than the turn on times.
Ah, you are building a dual PSU with one inverting PSU. I still think you should consider using a "standard" DC-DC converter, which is much easier to control and stabilize. It will probably have a better efficiency too.
Switched capacitor setups are mostly used in low-power applications. The major drawback is that the output voltage is dependent on the load and is hard to keep at a constant level. Mostly you will find them where the load is known to be relatively constant.
Alex555 wrote:What value inductor and capacitor should I use?
That depends entirely on the ripple-current and ripple-voltage you want to achieve. I would suggest you pick up (LT)Spice or equivalent simulation package and simulate your schematic to see what will happen (with or without inductor). There are too many unknowns and there are many differential equations to be solved to give you sufficient values. The inductor should be small though. If it is too large, you will get a very high voltage spike when the switch turns off.
Alex555 wrote:And what do I need pwm for?
None at all... I was thinking switching PSU.