Abstract—This article describes the design considerations and performance analysis of a new single-phase to three-phase in-line uninterruptible power supply (UPS) with a reduced number of switches . The proposed topology uses only 5 active switches, which reduces the system cost compared to traditional 10-switch topologies. The proposed inverter consists of a single-phase rectifier/charger, a two-phase/three-phase inverter connected to the load, a battery bank, a DC link capacitor and an AC inductor. Detailed operation and analysis of the circuit along with simulation results are also presented to verify its feasibility. Keywords: uninterruptible power supply (UPS); Single-phase to three-phase conversion; Reduced switchesI. INTRODUCTIONThe introduction should provide general context and review of the paper or work done by other engineers in the field. It should also contain a literature review, the objective and scope of the paper. Leave a space between two paragraphs (Do not indent paragraphs). Uninterruptible power supplies (UPS) are today essential equipment for powering critical and sensitive loads. They protect sensitive loads against many disturbances existing in the electrical network such as voltage variations, transients and harmonics. Applications for UPS systems include medical facilities, life support systems, data centers, emergency equipment, telecommunications and industrial processing systems. Ideally, a UPS should provide clean, uninterrupted power to the load, while consuming a sinusoidal power factor close to unity. current from the input power supply. Additionally, static inverters must be able to switch between utility batteries and storage batteries as alternative energy sources. This switching must take place within zero or minimum delay...... middle of paper......", 0-7803-7262-X/02/$10.00 Q 2002 IEEE.[20] M. Niroomand, HR Karshenas, “Review and Comparison of Control Methods for Uninterruptible Power Supplies”, Power Electronics and Drive Systems and Technologies Conference, PEDSTC2010, January 2010.[21] HW van der Broeck and JD van Wyk, “A comparative study of a three-phase induction machine drive with a minimized voltage-fed inverter under different control options,” IEEE Trans. Ind.Appl., vol. IA-20, no. 2, pp. 309-320, March/April. 1984.[22] Mr. Niroomand; HR Karshenas, “Design and Implementation of a New Hybrid Learning Control Strategy for Three-Phase Inverters”, Electrical Machines and Systems, 2008. ICEMS 2008. International Conference on, vol., no., pp.1732- 1737, October 17-20, 2008.[23] A. Emadi, A. Nasiri, SB Bekiarov. “Uninterruptible Power Supplies and Active Filters” 2005 by CRC Press LLC.