Design and Development of Transformer-less UPS

Abstract

Continuity and reliability of electrical power is most important criteria for any power supply desirable used for critical loads. Uninterruptible power supply (UPS) provide features such as continuity power supply and power conditioning in the connected system. In this project the scope Transformer-less Online UPS is planned to be designed studied and developed. In conventional online UPS, isolated step up transformer are used in order to increase the output voltage to desired level. In this approach the current in the primary side is more and there are severe saturation problems associated with the transformer. This results reduced efficiency of UPS. In order to remove the output transformer, more number of batteries are to be connected at DC link in order to achieve desired output voltage. This results in large size, makes system bulkier and costlier. In this project Bi-directional chopper will be used to reduce the number of Batteries as well as its size. This reduces overall cost of the system. Controlling the duty ratio of Bi-directional chopper, battery can be charged and as well as the voltage can be boosted at dc link of inverter. Scope of the project involves reducing no. of batteries as well as to design a UPS system catering 100VA load.