Review and Comparison of Modular Power Converter Architectures for EV Fast Chargers

This paper provides a comprehensive analysis of various state-of-the-art modular, bi-directional, isolated power converters for high-power (300 kW - 1 MW) applications like fast EV chargers which are directly interfaced to the medium voltage (MV) grid to increase the system efficiency. Traditional low-frequency transformers increase the size, weight, and cost of the overall installation of the EVs to the MV grid interface. As an alternative, various high-frequency modular converter topologies are used which provide a more compact solution. A typical design case study is considered for a 500 kW modular converter system, intended for a fast EV charger. Multiple topologies are evaluated in this study, considering key factors like efficiency, DC-link capacitor size, and overall device and capacitor cost. A thorough performance comparison is carried out by designing the isolated DC-DC stage of all the topologies using a conduction-loss minimization-based optimization approach.