中文摘要：

提出一种基于零电流转换（ZCT）的新型三电平Buck变换器拓扑。与传统Buck硬开关相比，此拓扑增加了一组由辅助开关管、谐振电感以及谐振电容组成的辅助支路，在开关占空比一定范围内可调的情况下，实现了功率开关管和辅助开关管的零电流开关（ZCS），同时实现主二极管的软换流。由于三电平自身的特性，主功率管的电压为输入电压的一半，适合于高电压大功率场合。在分析该变换器的工作原理基础上，研究了其工作特性，讨论和分析了主开关管实现ZCT的条件。基于Saber仿真软件验证了电路分析的正确性和设计的可行性。

英文摘要：

A novel zero-current-transition （ZCT） three level buck converter was presented. Compared with conventional three level buck converter, the branch consisting of an auxiliary switch, a resonant inductance and a resonant capacitor is added. The topology can achieve the main switches and the auxiliary switches zero-current- switching （ZCS） with an adjustable duty-cycle, the soft commutation of the main diodes can also be achieved. Because of the own characteristic of three level which makes the voltage stress of main switches half of the input voltage, suitable for high input voltage and high power density occasion. The converter＇s operational principle was illustrated. The conditions of ZCT were also analyzed. The simulation results based on Saber indicate that the converter has good performance.