Review and Comparison of MV grid-connected Extreme Fast Charging Converters for Electric Vehicles

This paper presents a comprehensive review of the various state-of-the-art extreme fast charging (XFC) converters used for the charging of electric vehicles (EVs). The high power EV chargers used in XFC station with power range of 150–400 kW are directly connected to the medium voltage (MV) grid instead of low voltage (LV) grid to improve the system efficiency. The conventional low-frequency transformers (LFTs) used in extreme fast EV chargers increases the size of overall installation. The integration of EVs to the MV grid through a high frequency solid-state transformer (SST) provides better controllability and compact solution. In this paper, detailed working principles with thorough performance evaluation of SST based topologies used in XFC is presented. A comparative study of these topologies based on the use of number of semiconductor switches, passive components, efficiency, redundancy and converter's ability to work in STATCOM mode is carried out. Two simulation case studies are presented for DAB based fast charging converters.