High-Efficiency SiC-Based Isolated Three-Port DC/DC Converters for Hybrid Charging Stations

This article proposes a novel isolated three-port dc/dc converter based on a series resonant converter and a dual active bridge (DAB) converter for electric-vehicle charging stations with fast and slow charging functions. With this three-port structure, the proposed converter has fewer components, which results in lower system cost and volume compared with separate charger systems. A simple control method using phase-shift and frequency modulations was developed to control the output power of the fast and slow charging ports simultaneously. An optimal phase-shift angle was also derived to minimize the transformer current for when only the DAB converter is operated for slow charging. To verify the converter operation, a 5-kW SiC-based prototype with a power density of 2.74 kW/dm3was built and tested with an input voltage of 600 V. A high-efficiency performance over a wide output voltage range has been achieved, and the peak efficiency is 98.2% at the rated conditions.