How use 3-phase mains with phase-neutral voltage at DC bus

What is your maximum input AC voltage?

If it is >300 VAC, do a search on this site for "StackFET".

I want to use the same smps (http://www.powerint.com/sites/default/files/images/schematics/di146_0.gif) with the same AC input range (universal range) but now my system has 3-phase input and my power supply must works although only was conected one phase. I have mounted and used the same smps and only changing the input rectifier, (neutral at negative bus and three-diodes bridge at positive bus). This works right but my bus capacitor is too huge and I must pass EMC.
I think that I don´t need StackFET. I want to now if you have some design example with this input.

1) Why is your new bulk cap "too huge"? Voltage, or required capacitance?
2) What is the new maximum voltage on your bulk cap when your AC voltage is at a maximum?
3) What other problems are you trying to solve?
4) If you are trying to solve EMI, pls. explain your EMI test setup, and what standard you are trying to meet.

1) Both (22uF in total and 700V)
2)700V
3)I will have available sometimes 3-phase, 2-phase or single phase. The smps must works right in all cases and not works if the user conect one phase instead the neutral. The last condition is solucionated with the overvoltage sense.
4)EMI Conducted Test

The nominal phase voltage is 230V +-10%

Show me how your overvoltage sense works. I want to make sure the TOP258 never switches, even once, with the risk of input voltage >400Vdc such that Vds > 700V (MOSFET rating).

35W requires a total bulk input capacitance of about 33 uF.