Research on Wide-Voltage DC/DC Converters for Electric Vehicle V2G Systems

To address the challenges of achieving soft switching over a wide voltage range and high control complexity in converters for vehicle-to-grid systems, this paper proposes a cascaded wide-voltage bidirectional DC/DC converter suitable for V2G applications. The front stage of the converter employs a Four-Switch Buck-Boost circuit, which achieves zero-voltage switching for all switches through quadrilateral inductor current control. Additionally, a fuzzy PI control strategy is integrated to dynamically optimize and adjust timing, thereby enhancing dynamic response performance. The rear stage adopts a symmetrically structured L-LLC resonant converter to achieve soft switching and bidirectional power flow. Through theoretical analysis, the gain relationship and soft-switching conditions of the FSBB circuit are derived, and a fuzzy rule-based adaptive PI parameter adjustment method is designed. Simulation results demonstrate that the proposed converter operates stably across a wide voltage range of 300~800 V, with low output voltage fluctuation, minimal overshoot, and soft switching achieved for all switches in both charging and discharging modes.