Medium-voltage Fast Charger for Electric Vehicles
DC fast charging stations are becoming more prevalent as the number of electric vehicles (EVs) on the road have increased significantly. In order to shorten the charging time and extend the driving range of EVs, the development of high-power, off-board charging stations is necessary. The conventional architecture of a DC fast charger incorporates either a local or a centralized front-end converter that interfaces with the medium-voltage (MV) grid via a low-voltage (LV) line frequency transformer, as shown in Fig. 1(a). However, this type of architecture is limited due to its large operational and installation costs. This work proposes a different power delivery solution that includes an isolated dual active bridge (DAB) converter for a MV-connected EV charging architecture. This work focuses on the design and architecture of the DAB converter, which aims to interface between the MV transformer and the EVs. The detailed design of the power stage, including the circuit operation, gate drivers, transformer, and hardware testing results, is presented.