A Dual-Active Bridge Converter with a Wide Output Voltage Range (200-1000 V) for Ultra-Fast DC-Connected EV Charging Stations

This paper proposes a wide voltage range bidirectional DC/DC charging converter. The proposed converter interfaces the fixed charging station DC-bus to the electric vehicle (EV), featuring a 200-1000 V charging voltage range. The wide voltage range is critical for future proofing of charging stations to support existing and next generation EVs, while also enabling its use for different applications, leading to major benefits in the economy to scale. Multiple charging converters have been previously proposed, but rarely has there been one which focused on the special needs of a DC-connected station while also considering a universal charging voltage range, and cost-effectiveness. As such, a universal charging converter is proposed to fill the research gap and address said needs. First, the proposed topology is introduced, and the operation principle and mode-transitioning scheme are analyzed. A converter design optimization strategy is also proposed, specifically for EV chargers, which takes an energy-based approach using data collected from actual EVs charging sessions. The experimental results and analysis for the 10 kW, 1 kV converter prototype validate the feasibility of the proposed converter, performance, and design approach.