부산대학교 도서관

Abstract This paper proposes a new wide range bidirectional buck‐boost dc‐dc converter with improved voltage gain in either forward (discharging) or backward (charging) direction for electric vehicle (EV) applications. The converter has high‐voltage gain ratio with no theoretical limits in the output voltage in both directions, and presents a good balance between the component count, number of conducting components, semiconductor device ratings, having direct connection between input and output terminals, and efficiency which makes it a practical solution for the EV charger levels 1, 2, and 3 power converter unit. The operating principle, steady‐state characteristics including the current and voltage stress of the switches, and comparison with other state of the art dc‐dc bidirectional converters are explained in detail. In order to validate the theoretical analysis, a 500 W, 200 V or 40 V to 180 V laboratory prototype is implemented. The obtained results confirm the applicability of this structure and demonstrate a peak efficiency of 97.2% in the forward and 97.6% in the backward direction modes of operation.