全桥结构中的无源、无损耗软开关技术

Research of Passive Lossless Soft Switch in Full Bridge SMPS

开关电源的高频化使得功率开关的损耗加大 ,采用软开关技术是减小该损耗的有效手段。本文提出了一种采用无源器件构成无损耗吸收回路的结构 ,可使得全桥 PWM开关电源中的开关管工作于零电流—零电压的软开关状态 ,以提高功率变换效率。通过对电路工作原理和能量转移关系的分析 。

As the working frequency of the switches in SMPS(Switch Mode Power Supply) increases, the switching loss increases, too. Soft switch technique can overcome this problem. In this paper,a novel lossless snubber constructed by passive elements is proposed. By using this structure in a full bridge PWM converter, the main switches are all working in ZCS (Zero Current Switch) and ZVS (Zero Voltage Switch) states. The operating theory and energy transfer relationship are studied, some key design parameters are also mentioned.This structure can enhance the overall efficiency and still keep low voltage and current stresses of the main switches.