新型零电流PWM全桥DC-DC变换器

为降低IGBT在关断过程中所产生的损耗,提高电源的开关频率.通过在变压器副边增加一个由谐振电感、谐振电容、辅助箝位二极管以及辅助开关管组成的辅助电路,在主开关管关断之前短暂开通辅助开关管,通过谐振电感和谐振电容之间的谐振使原边电流迅速复位,从而实现主电路开关管的零电流开关(ZCS).实验结果表明,此变换器可在全负载范围内实现所有开关管的ZCS和输出整流管的软换流,其辅助电路的谐振电感还具有帮助主电路实现主开关管软开通的功能.这种拓扑结构简洁,可以较好地实现软开关且不会增大整流二极管的电压应力,变换器的效率也达到了90%以上且有提升空间.

A novel ZCS PWM full bridge DC-DC converter

To reduce loss caused by turn-off process of insulated gate bipolar transistor(IGBT) and improve switching frequency of power supply,an assisted circuit composed by a resonant inductor,a resonant capacitor,an aided clamping diode and an aided switch tube is proposed.The aided switch tube is turned on transiently before the main switching tubes close.The primary current is reset rapidly through the resonance between resonant inductor and resonant capacitor.Thus zero current switching(ZCS) of main circuit switching tubes can be realized.The experiment results show that with this converter the ZCS of all switching tubes and the soft converting of output rectifiers can be realized under any load.The resonant inductor in the assisted circuit is also helpful for realizing soft conduction of main switching tubes.This topology is concise and soft switching is realized without increasing voltage stress of rectifiers,the efficiency is over 90% and is hopeful to be further improved.