DC-AC converter with high frequency DC link for UPS applications

An uninterruptible power supply (UPS) is an emergency power source. It continues the supply of power after the mains supply has failed. The majority of UPSs are AC; they produce a supply like the AC mains supply. This paper deals with the DC-AC power stage design, as an integral part of a UPS. The input voltage for the power converter is supplied by a set of backup batteries, while the output voltage has the following characteristics: sinusoidal waveform with THD <3% (total linear load); synchrony with mains power supply; and high frequency isolation. The authors show the principal considerations used for optimum configuration selection, inverter PWM technique, power devices, dead time effect compensation and total system efficiency. Theoretical and experimental results show good agreement for both voltage and current waveforms under different load conditions.