Implementation of interleaved bi-directional DC-DC converter with multi stage constant current charging based on fuzzy control for disturbance-resistant electric vehicle battery swapping stations

This research presents an interleaved bi-directional non-inverting buck-boost converter designed for public electric vehicle battery swapping stations (BSS). This study solves the critical problem of BSS vulnerability to main power outages, which threatens their operational reliability. The developed solution is a device that not only performs efficient charging but also functions as an emergency power source, utilizing power from connected batteries during a grid failure. The methodology incorporates an interleaved topology and a multi-stage constant current (MSCC) charging method controlled by a fuzzy logic controller (FLC). Experimental results show the interleaved operation successfully increased power capacity up to 1.1 kW, achieving an average efficiency of 93.44%. A distinctive feature of the result is the reduction of the output current ripple by 47.7% down to 0.92%. This is explained by the ripple-cancellation effect inherent to the interleaved design, which is a key feature for preserving long-term battery health. Furthermore, the MSCC method achieved a 13.7% reduction in execution time compared to the conventional constant current-constant voltage (CC-CV) method, with a total charging duration of 66.8 minutes. This validated prototype successfully demonstrated a seamless and automatic emergency mode transition during a power failure, directly answering the BSS reliability challenge. The prototype also confirmed its bidirectional functionality and seamless mode transition from standard charging to emergency power supply mode. The scope of this research provides a practical and high-performance integrated solution for BSS, effectively addressing vulnerability issues by improving reliability and charging time efficiency, ensuring continuous service.