How to calculate the DC rail voltage for Variable frequency drive (VFD) for single phase induction motor?
The DC voltage is calculated for the maximum AC voltage you want the converter to output. For a single phase 220VAC the DC would be:

Vdc = sqrt(2) * Vac + x + y + z = 1.41 * 220 + x + y + z = 310.2V + x + y + z


Where x is the maximum voltage drop of all the components through which the current flows and y should be added to ensure a low THD of the waveform due to the switching deadtimes and limitations of the controller. Here z stands for the half voltage ripple of the DC link capacitor. I would let:

x = 10-15V
y = 10% * 310 = 31V
z = 10%/2 * (310+x+y) = 18V


So total DC voltage you need to get a nice and clean 220VAC sinewave would be:

Vdc = 310.2V + x + y + z= 380V DC.


Of course you should verify x, y and z components for your design, but this is the basic route you should follow.