Performance Evaluation and Operation of DSP Control UPS System

Abstract

An uninterruptible power supply (UPS) is a power controller that gives emergency electricity to a load when the mains energy fails. In on-line UPS, the load is always connected to the inverter though the UPS static switch. Specialized expertise is required for collection, analysis, and dissemination of technical information relating to high quality uninterruptible power systems. Inherent in these responsibilities is the coordination of technical and contractual matters relating to the procurement and installation of uninterruptible power supply (UPS) systems which are required to support these facilities. The proposed circuit incorporates an AC/DC & DC/AC converter, which provides power factor correction and to assure feedback control. In our project when the AC main is available, the rectifier circuit will supply the power to the inverter as well as to the battery and battery will be charged. If the supply power fails suddenly, the battery will supply power to the inverter without any interruption and delay. In the constant current charging technique, a digital charger is designed and is controlled through PIC12F675 microcontroller. In the realized system, The PIC16C73B was used as microcontroller. It was used to generate sinusoidal PWM (Pulse Width Modulation) signals that are used to drive n-channel MOSFETs in inverter to assure feedback control and display units. The power circuit of the proposed UPS system is presented and analyzed. Circuit models are derived and a UPS digital control system using a digital signal processing (DSP) with microcontroller is developed. The uninterruptible power supplies (UPS) are widely used as standby power supply during interruption of regular power supply due to load shedding, power failure, power fluctuations including telecommunication systems, medical systems, industrial control systems etc.

Keywords: Uninterruptible power supply, PIC12F675 microcontroller, Pulse Width Modulation, MOSFET, power fluctuations