Semiresonant Half-Bridge Zeta Converter With Reduced Turn-OFF Currents for High-Efficiency Power Supply

This article presents a semiresonant half-bridge zeta (HBZ) converter for high-efficiency power supply. Since the proposed converter utilizes a primary inductor and secondary capacitor as a resonant tank, it can make a resonant operation during the on-state of a low-side primary switch. Therefore, the proposed converter can effectively reduce turn-off currents of the low-side primary switch and the secondary diode without any additional component and control scheme, which decreases turn-off switching loss and reverse-recovery loss. Moreover, the proposed converter can maintain advantages of the conventional HBZ converter such as high input/output (I/O) voltage gain and wide zero-voltage-switching (ZVS) range with the proposed design procedure. As a result, the proposed converter can improve its efficiency over the entire load conditions compared to the conventional HBZ converter. A 250 W, 300-400 V input, and 56 V output prototype has been built and tested to verify the effectiveness of the proposed converter.