Design and Development of ON-Line Uninterruptible Power Supply

Abstract

UPS is a substitution of energy cut offs. It is always safe for us to protect our load by connecting it to an UPS. An UPS has its own rechargeable battery which pro- vides emergency power for the system immediately when the mains supply fails. The proposed ON-Line Uninterruptible Power Supply (UPS) offers AC voltage regulation on continuity basis which incorporates with the controllable battery charger. The battery used is Lead Acid Type battery. The Charging Control technique used for battery is constant current charging. The Constant Current is achieved by control- ling the duty cycle of battery charger (or step-down chopper). In proposed scheme, protection of battery over charge and battery under charge is available with relay trip through PIC 16F877A microcontroller by monitoring voltages on continues basis. The backup of battery takes place the load without spikes or delay when the mains power gets fails or interrupted. Based on the proposed Constant Current Charging method, design of a digital charger is done and the charger is control through PIC 16F877A microcontroller. The inverter used is simple square wave inverter.