DC-DC Half Bridge Converter Capacitor Selection?
Bridge caps should be high, like 470u or 680u, depending on the input power and required input ripple. But for most applications, the filter cap can be selected according to 1uF per output watts formula. For example, in my 400W converter design, I used two 680uF caps in series.

We always want bridge capacitors to have equal voltage across them. So don't forget to put equal resistors across C3 and C4 to guarantee dropping equal voltage across them. Or else, high tolerances of the caps (15% or even 20%) will determine the divider ratio. That resistors will also help discharging the caps. Take switching frequency into account while selecting that resistors. You want the caps to discharge before the next cycle, right?

CB is blocking capacitor and can be anything between 470n and 1u. But voltage rating of the cap is important and should be at least half of maximum DC bus voltage. For example, if the input varies between 185 and 265Vac then VIN(max) = 370VDC. So CB can be a 1u/250V.