To adapt the UPS converter output voltage to the line voltage required by the load and to provide galvanic separation between UPS and the load.
The transformer with built-in inductance is applied for inverter transformer usually. The integrated transformers are connected at the output of a PWM converter,with a built-in inductance. The integrated inductance,in combination with the output capacitors,operates as a filter and restores the sinusoidal waveshape of output voltage.