Single-Stage Series-Connected Isolated Converters for MVAC to DC Applications

This paper presents an novel fast electric vehicle (EV) charger configuration suitable for direct medium voltage (MV) connection. The idea is based on the multi-cell boost (MCB) structure and shares its advantages in terms of modularity, low line inductor requirements, high-frequency isolation and good semiconductor utilization. However, instead of using a two-stage conversion approach, where each cell includes power factor correction (PFC) rectifier that is followed by isolated dc-dc converters, a single-sage approach is implemented. In this case both PFC and isolation functions are realized with a single cell based on isolated current source converters (CSCs). The topology structure and its possible configurations are presented, followed by some design considerations. Next, some of the possible CSC topologies suitable for the proposed single-stage MCB cell are described, followed by simulation and benchmarking of selected topologies.