basic: UPS transformer choice

[gvnl]

hello:
for building UPS, let's say 12/220V for example, there is two topologies: either a 12-0-12/220V with two transistors, or a 12/220V with a full-bridge of 4 transistors.

what's the advantages and inconvenients of each topology?

Thanks

 

[xaccto]

the 12V-0V-12V/220V
This has the danger of current imbalance in the transformer, leading to saturation on one leg, and resulting in destruction of that transistor.
This is mitigated by measuring the current in each transistor switch, so current regulation say skipping a pulse on one side to re-address any imbalance.

The full bridge avoids this problem by completely reversing the current (hence magnetic field) in the transformer on the one winding.
Disadvantage is there are 2 switches in series - so double the switch losses.
Yet this I see is the recommended topology for high power inverters.

There is a lot of reading material if you google, can be hard to sort through it all though.