Development of LVDC/AC UPS Intergrated Power Conversion System with ESS Function

Abstract

This paper introduces a UPS(Uninterruptible Power Supply) system that has an Energy Storage System(ESS) and can provide both LVDC(Low Voltage Direct Current) and AC outputs simultaneously. This system integrates an offline UPS, which is composed of bidirectional inverters and a battery converter, with an LVDC system consisting of a DC-DC converter. The LVDC system is designed to produce LVDC output by sharing the UPS’s DC LINK, thus The LVDC system offers the advantage of compensating for power outages. Moreover, the proposed system has an ESS function that can distribute peak load through load leveling. The performance and functionality of the proposed system were validated through experiments in various scenarios, including normal operation, power outage situations, charging, and discharging.