Improved DSP-controlled online UPS system with high real output power

Abstract

A circuit topology is proposed for single-phase online UPS systems. The proposed circuit incorporates a built-in bidirectional AC/DC converter, which provides power factor correction and active power filtering. The input stage, based on a bidirectional AC/DC converter, functions as a rectifier with unity power factor correction for normal AC line mode operation, and as an active power filter for outage mode operation. During input power failure, the bidirectional AC/DC converter functions as an active power filter, providing reactive power to the load. Simultaneously, the DC/AC voltage inverter output stage supplies real power from the battery bank to the critical load. The real power capability is improved compared with that of a conventional online UPS system, and extra loads can be connected to the UPS system during outage. The power circuit of the proposed UPS system is presented and analysed. Circuit models are derived and a UPS digital control system using a digital signal processor (DSP) is developed. Finally, simulated and experimental results obtained from a laboratory prototype are presented to confirm the feasibility and features of the proposed UPS scheme.

Control Architecture for Parallel Inverter in Uninterruptible Power Systems - Part I: Control Design and Experimental Results

“…Compared with offline and line-interactive UPS, online UPS, also named inverter preferred UPS or double conversion UPS, mainly aims at high power and voltage application due to the full controllability of its output voltage and decoupling capability of the utility and the load under power outage [9], [10]. For those aforementioned reasons, it is becoming the most commercialized UPS system in industrial applications.…”

“…Consequently, uninterruptable power systems (UPS) are receiving more and more attention from both engineers and researchers. According to the International Electrotechnical Commission Standard IEC62040-3, a UPS system can be divided into three categories, namely offline UPS [3], [4], line interactive UPS [5]- [8] and online UPS [9], [10] according to the energy flow direction under normal utility condition. Due to its outstanding capability of suppressing the utility distortion and interferences, online UPS systems are rapidly proliferating for both high power and voltage application scenarios [11]- [20].…”

Novel Transformerless Grid-Connected Power Converter With Negative Grounding for Photovoltaic Generation System

“…If the output signal v m of the amplifier is constant in a switching period, the duty ratio of the single-phase converter can be represented as [28] …”

Monitoring System for Uninterruptible Power Supply

“…UPS systems have enabled the improvement of power source quality, providing clean and uninterruptible power to critical loads such as industrial process controls, computers, medical equipment, data communication systems and protection against power supply disturbances or interruptions [1][2][3] . UPS provides stable supply to the system in the present or absence of the input supply [4] .…”

“…Commonly, the UPS topology can be classified as off-line UPS, line interactive UPS and online UPS. The three topologies were discussed in details in [2][3][4][5][6] .…”