Proposal of a 5kVA single-phase on-line UPS with high frequency isolation and power factor correction

Abstract

A high performance isolated double conversion uninterruptible power supply (UPS) with power factor correction using a high frequency transformer, and input voltages equal to 110 V/220 V is proposed. The arrangement is suitable to rack type structures because it has small size and reduced weight. For both input voltages, the proposed converter has almost the same efficiency processing the same output power. Other relevant features are soft commutation of the controlled switches in the chopper and the boost stage, simple control strategy that can be implemented with well-known integrated circuits, and the use of few batteries in series due to the step-up stage. Qualitative analysis and experimental results obtained for a 5 kVA prototype show a normal efficiency of over 87% for the worst case of input voltage and an input power factor of over 99%.