Fast DC-Type Electric Vehicle Charger Based On A Quasi-Direct Boost - Buck Rectifier

This work presents a DC-type fast electric vehicle battery charger featuring low switching losses. Herein, a conventional three-phase two-level voltage source rectifier with low capacitive energy storage operates with a discontinuous PWM modulation where each phase-legs stops switching for 240° of the grid fundamental period, i.e. only a single phase-leg switch every 60°. In this case, this AC-DC converter loses voltage controllability of the DC-link and thus a buck-type DC-DC converter is cascaded in order to provide the necessary voltage regulation and current limitation for the charging process of the electric vehicle. The presented circuit is benchmarked against other solutions for a designed 50 kW power capability battery charger when considering the charging of a 30 kWh Nissan Leaf. The results show a superior power efficiency of the studied system.