In the "old days" the powerinverter had a "big" ironcore transformer, and these used a pushpull-circuit to
drive a 12v transformer in "reverse" to step up the voltage rate.
These type you can forget to use for this project, 50/60hz and to slow.
Now days a highfrequency driven ferite transformer is used to make half the rated outputvoltage.
The switchfrequency is around maby 50khz and benefit from this is that you get 95+% efficiency.
The H-bridge "makes" the +-110 which will be 50Hz 220v AC
Just take one appart and have a look, you will better see what am talking about.
And yes, if you want 110v you must use a european model.
You can probably squeeze a few extra volt out by modifying the feedback.
So if you put a good quality fast charging capacitor before the H-bridge and after the transformers rectifier, i think this could be possible.(Just make shure the H-bridge can take the peak current)
I understand that the peakcurrent and voltage are high, but i have not seen any commonraildiesel with a
powerplant under the hood, i would believe this could be done with a modified inverter.
It is not so difficult to make your own step up supply from scratch, but the inverters as you say are very cheap.
SG3525 is a nice circuit you can use to make the powersupply before the H-bridge.
Am on vacation, when i arrive home i can take a look, i have one i can try to modify.