Forking a 3 phase 380V line into three 220V single phase?
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. The connection scheme - five single-phase loads on a three-phase supply.

What you are proposing is normal practice. Most single-phase circuits are just one of a three-phase supply with return on the neutral.

Ideally we try to balance the loads on all three phases but there is no way to do this with your setup. It will be particularly unbalanced if the VFD switches on and off while the PSUs are all on.


  Could I connect everything over a 3 phase 380 V line (5 wires 2.5mm each, 3 &times; 16amps fused)? 


That sounds OK but you'd need to check the regulations for your country.


  But I am not sure if the single neutral can hold everything.


The neutral only has to carry the difference in the currents. You will be able to find plenty of tutorials on this online.