Soft-switching bidirectional isolated three-phase DC-DC converter with dual phase-shift and variable duty cycle

This paper presents the analysis, design, and experimental results for a soft-switching bidirectional isolated three-phase DC-DC converter with dual phase-shift and variable duty cycle. The topology uses three single H-bridges in the primary side and a three-phase inverter in the secondary side. The high frequency isolation is ensured by using three single-phase transformers connected in open delta-wye configuration. Variation of both phase shift angles between single H-bridge legs and/or primary and secondary side allows the power delivery control. This additional flexibility allows the system to maintain a low reactive power flow. The variable duty cycle is used to ensure a constant voltage bus and ZVS soft switching operation. A detailed analysis is presented considering a model based on fundamental components. Experimental results for a prototype are performed to validate the model used.