Design and Implementation of a Lead-Acid Battery Charger with Multi-State Charge Algorithm

Abstract

Batteries are the heart of the back-up supply systems. Battery charging is a complex electrochemical process, in which the discharged electric energy must be replenished from the electric network. The quality of charging process is critical to battery life and performance of battery. So, the battery charger plays an important role in life and performance of batteries. Battery charger is an electric/electronic device that converts the incoming AC line voltage into a regulated DC voltage to meet the charging needs of respective batteries. With the development of power electronics technology, charging using devices like SCRs, MOSFETs, and IGBTs is implemented. Among all the charger topologies, SMPS battery chargers are compact and efficient, and hence, their use is viable solution to charge lead-acid battery.

This thesis demonstrates the different lead-acid battery charging methods and amongst them best suitable methods for lead-acid battery charging. A lead-acid battery charger with multi-state charge algorithm has been proposed. For SMPS based lead-acid battery charger, the power supply plays an important role. Flyback converter topology is being used in SMPS. It offers a number of advantages like single or multiple isolated output, operate over wide range of input voltage variations, and cost effective than other SMPS topology. Proposed flyback SMPS based lead-acid battery charger has universal input range from 85 Vac to 265 Vac and also capable of charging the battery in four different charging states. Finally, advantages of multi-state charge algorithm have been realized over conventional charging methods.