Online UPS (HF)

This UPS is a double conversion on-line UPS that conditions the raw mains and supplies continuous, clean single-phase power to the critical systems. While feeding the load the UPS also keeps the battery constantly charged. If utility power fails, the UPS will continue to supply clean power to the load without any interruption. If the power failure outlasts the backup time the UPS will shut down in order to prevent a total discharge of the battery. When the line voltage is restored the UPS will start up again automatically providing power to the critical load and recharge the batteries.

The block diagram is shown on figure.

Transients on the mains are reduced by an input filter.
AC-power is rectified and regulated in the rectifier which feeds the power to the inverter and battery converters too keep the battery bank fully charged.
The inverter converts the DC-power back to AC-power, which is delivered to the load.
The battery provides power to the load during a mains failure.
Battery converter increases the battery voltage to the right level for the inverter.