New topology for single phase UPS systems

This paper presents a new converter topology, based on a single switch ac/dc or dc/dc boost converter combined with a half bridge inverter, suitable for on-line single phase UPS systems. The converter uses only four active switches, including the one for maintaining the charge of storage battery, to realize very desirable features. These include sinusoidal input currents, a common neutral connection - eliminating the requirement of an isolation transform, low voltage storage battery as well as its charge/discharge regulations. Further, higher ac-dc conversion efficiency can be obtained due to reduced voltage stresses on the switch in the boost converter during normal operation, compared with conventional half bridge converters. Detailed simulation results and experimental results are included in this paper.