Integrated Quasi-Two-Stage Buck-LC Converter With Wide Voltage Gain Range

An integrated buck-LC converter for a wide voltage range is proposed in thisarticle based on a quasi-two-stage structure. In the integrated quasi-two-stage buck-LC (IQBLC) converter, the LC resonant stage is under dc transformer (DCX) mode and the buck stage can achieve voltage regulation. The buck stage is integrated into the DCX stage, which can reduce the number of switches. The inductor of the buck stage only transfers a part of the output power, which benefits efficiency improvement and zero-voltage-switching (ZVS) achievement. Different working modes and modulation strategies are presented for the IQBLC converter to further extend the voltage gain. The soft switching of all switches can be realized under different modes and loads. Besides, a duty cycle control trajectory is proposed to realize continuous voltage gain adjustment under multimode operation. The voltage gain characteristics, partial power characteristics, ZVS conditions, and discontinuous mode constraints of the LC stage are analyzed in detail in this article. Experimental results are obtained from a 1-kW prototype to validate the effectiveness of the proposed converter.