Transient Response of a CC-CV Integrated Battery Charger for Consistent Charging of Lightweight EVs During Grid Voltage Fluctuations

The predominant solution for charging lightweight EVs such as electric three-wheelers (ETW) and e-rickshaw has been a line frequency step-down transformer with rectifier due to its low cost and ease of use. This conventional charging system cannot regulate output voltage or current due to the lack of any feedback or sensing. Batteries charge inconsistency due to lack of control circuitry, resulting in overcharging, overheating, and, most significantly, energy waste and accelerated battery life degeneration over time. This paper presents the design, development, and transient response with performance analysis of a charging system based on high-frequency H-bridge DC-DC converter. The designed system has digital closed-loop control for individual regulation of output current & voltage while being small and lightweight. The charger allows batteries to be efficiently charged at preset voltage & current values depending on desired charging profile based on battery chemistry and SOC. A hardware prototype of 60V, 1.2kW is created for performance analysis and evaluation.