Switch-Multiplexed Quasi-Two-Stage Isolated Bidirectional Buck-DAB Converter With Full Load ZVS Range

In this letter, a switch-multiplexed quasi-two-stage buck-dual-active-bridge (DAB) (SMBDAB) and its modulation strategy are proposed. Under the quasi-two-stage buck-DAB architecture, one bridge of the primary side of the proposed converter is multiplexed as both the bridge of the buck circuit and the DAB circuit to reduce the power switches. In addition, with the voltage-matching modulation, multiplexing still ensures that the voltages on both sides of the leakage inductor of the DAB circuit are always matched when the voltage gain of the converter changes, and thus, the zero-voltage switching (ZVS) of all the switches can be achieved. Furthermore, the partial power transfer characteristics of the buck circuit still maintains, which could reduce the power rating of the inductor for the buck circuit. The working principle, power transfer characteristics, and full range ZVS design are analyzed. Finally, the effectiveness of the SMBDAB converter is verified through experimental results from a 1kW prototype.