Wide Output Voltage Range Three-Phase Bidirectional Non-Isolated Hybrid AC/DC Converter

This paper proposes a non-isolated converter topology capable of achieving a wide output voltage range (200 V to 1000 V). This design addresses the limitations of traditional two-stage isolated and single-stage chargers, where the use of high-frequency resonant converters often restricts the power density and narrows the output voltage range. The proposed topology integrates a buck-stage rectifier circuit with a three-level DC/DC boost stage. To ensure high-efficiency operation and prevent redundant high-frequency switching, a coordinated modulation strategy is developed. When the system operates in buck mode, the high-frequency switches in the boost stage are clamped; when in boost mode, the buck-stage switches are clamped; and during transition mode, both stages coordinate their switching behavior based on the required output voltage. This modulation strategy ensures that the minimum number of high-frequency switches are active at any given time, thereby reducing switching losses caused by hard switching and enabling a smooth transition across the entire output voltage range. Simulation results validate the feasibility and effectiveness of the proposed topology and control method.