A Coupled-Inductor-Based Nonisolated DC-DC Converter With High Step-Down and Wide Input Voltage

In the data center applications, the bus converter not only needs to achieve high step-down gain but also can keep stable output for data back-up when the bus voltage drops dramatically due to fault. Thus, a coupled-inductor-based nonisolated DC-DC converter with high step-down and wide input range is proposed in this paper. The proposed converter utilizes the coupled inductor to obtain the high step-down capability and the series-capacitor to achieve zero voltage switching and zero magnetizing currents, which can help reduce switching loss and core loss. Thanks to the feature of the voltage gain, lower conduction loss at low input voltage and wider input voltage can be ensured. The feasibility of the converter is verified by detailed theoretical analysis and a prototype with the 36∼60 V input voltage, 3.3 V output voltage, and the 1∼10 A output current. The efficiency of the prototype can be maintained above 90% under all conditions, and the peak efficiency is 95.8%.