A Hybrid-Bridge and Hybrid Modulation-Based Dual-Active-Bridge Converter Adapted to Wide Voltage Range

Dual-active-bridge (DAB) converter based on single-phase shift (SPS) modulation is commonly used in energy storage systems. However, if the normalized voltage gain deviates from unity, the zero-voltage-switching (ZVS) feature and efficiency of the DAB converter deteriorate. To overcome this challenge, this article proposes a hybrid-bridge and hybrid modulation-based DAB converter adapted to a wide voltage range. The primary-side hybrid bridge operates in an intermediate state between the full bridge and the half bridge. Asymmetrical pulsewidth modulation (APWM) is introduced to regulate the dc bias across the blocking capacitor in a continuous manner. Due to the synergy between the hybrid-bridge structure and hybrid modulation scheme, a general voltage match between the energy storage unit and the high-voltage bus is always achieved. Moreover, the ZVS range is extended and the circulating current is well suppressed. Therefore, efficiency is optimized over the wide voltage range. The operational principles, circuit modeling, and design considerations are detailed. A 500-W converter prototype, linking a 100-200-V energy storage unit and a 300-V dc bus, is designed and tested to validate the concept. A 97.9% peak efficiency and good overall efficiency over the wide voltage range are reported.