High-Efficiency Design and Control of a Single-Stage 400 V/800 V EV Charging Station Using a Dual-Output LF Transformer With an ATS

The escalating global demand for high-power electric vehicle (EV) charging has driven manufacturers to adopt 800 V battery systems. However, the prevalent 400 V-centric existing EV charging infrastructure requires substantial modifications or additional conversion stages for 800 V EVs, leading to increased complexity, cost, and efficiency losses. This paper proposes a novel EV charging system architecture comprising a dual-output low-frequency (LF) transformer, an automatic transfer switch (ATS), an LCL filter, and a Vienna rectifier, operating under three-phase 380 V/60 Hz grid input. The system offers a unified, single-stage solution, efficiently supporting both 400 V and 800 V EVs without additional DC/DC conversion. Within this architecture, the LF transformer provides dual 380 V and 180 V outputs; the ATS selects the appropriate output, fed via the LCL filter into the Vienna rectifier for wide-range DC outputs. The Vienna rectifier strategically controls DC output current/power and AC input current/DC output voltage. Experimental results from a 100 kW prototype demonstrate a peak efficiency of about 97.8%, with total harmonic distortion (THD) performance maintained below 3.9% (current THD). Compared to conventional multi-stage systems, this proposed system offers demonstrably superior efficiency, stability, and flexibility, making it ideally suited for comprehensive EV battery systems due to its simplified structure and optimized control algorithm.