Hybrid DC/DC converter based on dual three‐level circuit and half‐bridge circuit

This study presents the system analysis and circuit implementation of a new hybrid DC/DC converter. The proposed circuit includes a dual three-level converter and an un-regulated half-bridge converter. The un-regulated half-bridge converter, shared the lagging-leg switches of three-level converter, is adopted to extend the zero voltage switching (ZVS) range of lagging-leg switches. The dual three-level circuit based on phase-shifted pulse-width modulation is adopted to regulate the output voltage and reduce the current stress of passive components on the output side. To overcome the high circulating current losses in conventional three-level converter, a resonant capacitor is used on the primary side to reduce the circulating current to zero in the freewheeling interval. The secondary windings of three-level converter and half-bridge converter are connected in series so that the rectified voltage on the secondary side is positive instead of zero voltage in the conventional three-level converter. Therefore, the output current ripple can be reduced. The main advantages of the proposed converter are low circulating current losses, low voltage stress of switches, wide ZVS range and less output current ripple. Finally, experiments based on a 1920 W prototype are provided to validate the theoretical analysis and the effectiveness of the proposed converter.