Online Transformer-Less Uninterruptible Power Supply (Ups) System With A Smaller Battery Bank For Low Power Applications

Abstract

Today there are numerous companies in Iran manufacturing Uninterruptible Power Supplies (UPS). However, in medium and high power range they manufacture online Double conversion transformer based UPSs, with thyristor controlled rectifier. In this paper the power topology, control algorithm and experimental results of the first commercial active front end 30 KVA transformers-less UPS in Iran is presented.

In many critical applications with sensitive loads, it is imperative to use transformer based UPSs. Transformer based UPS is proven technology that improves reliability and provides fault isolation. But today, transformer-less UPS market is growing rapidly. This is due to the benefits such as smaller footprint, higher efficiency and lower cost. Transformer-less UPS is now becoming a mature technology. However, there is no research paper or document describing the power topology  and control block diagram of one particular commercial Transformer-less UPS.