A single-phase UPS system based on TRINIT/sup y/ converter topology using voltage-regulated current-controlled feedback control approach

Abstract

A proposed single-phase uninterruptible power supply (UPS) system derived from a triple rectifier inverter neutral inter-Ty (TRINlT/sup y/) converter topology utilizing voltage-regulated current-controlled feedback approach is presented here. The proposed UPS model presents the advantages of high power conversion efficiency, unity input power factor (reactive power compensation), as well as low input and output total harmonic distortion (harmonic power compensation) in the voltages and currents under normal mode of operation. Meanwhile, during backup mode of operation, this UPS has the capability of providing grid isolation without any backward power feed into the faulted utility supply, while having low output voltage and current total harmonic distortion. It also eliminates the series transformer and the power factor corrector used in conjunction with the traditional stand-alone UPS, and it is impervious to load variations. In addition, this UPS has the desirable characteristics of making seamless transition from normal to backup mode during power failures and vice versa, as well as providing controlled voltage charging at the dc bus link. Lastly, the circuit structure is simple, light weight, and can be implemented at a low cost using the standard commercial available components. Simulation and some initial experimental results are presented to demonstrate the validity and efficacy of the proposed UPS system and control strategy.