Three-phase Medium Voltage DC Fast Charger based on Single-stage Soft-switching Topology

摘要

This paper presents a 350kW, high-efficiency, three-phase 4.16kV-AC medium voltage(MV) isolated power converter that can be used as a MV DC fast charger for battery electric vehicles using 800V battery packs and is interoperable with legacy vehicles with 400V battery packs. The proposed high power quality (PF≥0.98, THD≤5%) charging system comprises of three identical power modules, one for each phase with their outputs connected in parallel to deliver the charging power. The converter uses variable switching frequency and a combination of single and double phase shifts to achieve the dual control objective of UPF and ZVS over the entire operating range while minimizing the device current and maintaining the charging current constant. Design guidelines of input and output filters, high frequency tranformer and switching frequency range selection have been presented. Simulation results validate the proposed charging station design and operation.