Analysis, Design, and Performance of Isolated Three-Port UPS Converter for High-Power Applications

Abstract

In this paper, an uninterrupted power supply (UPS) and an isolated three-port bidirectional converter (TPBC) are developed by connecting a three-phase voltage source converter(VSC), a battery energy- storage system (BESS) and a grid-connected boost converter-fed three-phase DC/AC converter through a single three-winding isolation transformer(Tr). This design presents features that are suitable for multiple voltage electrical systems. The three-port power exchange is multi-directional which can be delivered either separately or simultaneously. In consideration of the safety requirements, electrical isolation is achieved between any of the two ports. Besides the power-flow concept, different operating principle stages, power flow equations, small signal model, network simulation model, and control strategy are discussed. Furthermore, the steady-state analysis are evaluated to determine the power flow equations. The control strategy proposed is based on single-phase shift control, with the small signal model for optimized controller design, which can predict the accurate frequency response and obtain a fast dynamic response. Meanwhile, this can be used in many applications of electronic power converters. The simulation results have been provided under various operating conditions, which confirms the effectiveness of the proposed control strategy. The result showed that the power management feature of the system was successful and waveforms are obtained. Finally, theoretical considerations and simulation results for different operating stages are verified by MATLAB / SIMULINK