基于新型箝位电路的低电压应力零电流开关半桥PWM变换器

提出一种基于新颖箝位支路的零电流开关半桥PWM变换器。与传统的不对称半桥变换器相比，该变换器在变压器的副边电路中增加了一条由辅助开关管与谐振电容串联组成的辅助支路。该变换器不仅能在整个负载范围内实现主开关管和辅助开关管的零电流开关以及所有二极管的零电压开关；而且通过无源箝位支路，消除了辅助开关管和整流二极管的电压尖峰；采用对称控制，因此变压器不存在电流偏磁，且主开关管的电压应力相等。详细分析箝位支路的工作原理和变换器的工作特性，并给出实现软开关的条件，实验结果验证了该变换器的可行性。

A ZCS PWM Half-bridge Converter With Lower Voltage Stress Based on a Novel Clamp Branch Circuit

A novel zero-current-switching (ZCS) half- bridge DC/DC converter with symmetrical pulse-width- modulated (PWM) control method is proposed based on a novel clamp circuit. Compared with conventional half-bridge topology, a branch comprising an auxiliary switch and a capacity is added in secondary circuit. The proposed converter not only achieves ZSC of all switches and zero-voltage- switching (ZVS) of all diodes at entire load range, but it eliminates voltage peaks across auxiliary switch and rectifier diodes benefiting from the passive clamp branch circuit. Furthermore, magnetic biasing does not exit in transformer since the main switches conduct symmetrically. Based on the analysis of the fundamental principles and characters, the condition to achieve ZCS is given. The performance of this new ZCS-PWM half bridge converter is confirmed by experimental results obtained from a 1 000 W, 30 kHz prototype.