Design and analysis of a low cost, high performance single phase UPS system

This paper presents design considerations and performance analysis of an on-line low cost, high performance single-phase UPS system based on a novel converter topology. The converter, consisting of an AC-DC/DC-DC boost converter combined with a half bridge inverter, uses only five active switches to realize very desirable features. These include sinusoidal input currents, a common neutral connection-eliminating the requirement of an isolation transformer, capability of voltage balancing control for the DC bus capacitors, low voltage storage battery as well as its charge or discharge regulations. Further, voltage stresses on the switches in the boost converter are reduced to half of those in conventional half bridge converters. A new, unified boost converter control strategy is also presented. Detailed computer simulation and experimental results are included in this paper to demonstrate the superior performances of the UPS system.