Closed-Loop Full-Bridge HF Converter Based Electric Three-Wheelers Battery Charger with CC-CV Charging Technique for Extended Battery Life

Abstract

A step-down transformer with rectifier operating at line frequency has been the predominant solution for charging electric three-wheelers due to its simplicity and affordability. This conventional charger operates at a fixed step-down voltage without any sensing or control of output voltage or current. Absence of any control causes the batteries to charge inconsistently which results in over charging, over temperature and most importantly waste of energy and faster degradation of battery life over time. Design and implementation of a locally developed high-frequency full-bridge DC-DC converter-based charging solution is presented in this paper. The developed charging system is compact, lightweight and features a modified closed loop digital control algorithm for independent control of output voltage and current. This system allows the batteries to be charged efficiently at predetermined voltage and current levels or to automatically follow a specific charging profile based on state-of-charge. A 1kW, 60V hardware prototype is also developed for performance analysis & comparison with existing solutions.