一种零电压零电流软开关直流变换器的研究

提出了一种零电压零电流软开关三电平直流变换器.利用耦合电感取代常规滤波电感，耦合电感所感应出的电压通过功率变压器反射回原边，使变换器在零状态时的循环电流减小至零，以实现内管的零电流关断.通过改变耦合线圈的匝比,可以任意设置用于电流回零的电压幅值，以调节电流回零时间.该变换器实现了外管的零电压开关和内管的零电流开关, 由于在零状态时一次侧不存在环流，减小了通态损耗, 提高了变换效率.实验样机验证了该电路的主要性能，电压电流实验波形显示了三电平的低电压应力特点和零电压开通、零电流关断的软开关性能.

A zero-voltage zero-current soft switching direct converter

A three-level zero-voltage zero-current switching(ZVZCS) DC/DC converter was proposed.A tapped inductor was adopted to substitute for the normal inductor,so that the circulating current in the zero state could be reset to zero.By regulating the winding ratio of the tapped inductor,the voltage used to reset the primary current can be adjusted conveniently,and the reset time can also be designed easily.The converter realizes zero-current tuning off for inner switching,and zero-voltage tuning on for outer switching.No circulating current exist in zero state,so that the loss in on-state was decreased,and the efficiency was improved.Experimental results varified the main characteristics of this converter with low voltage stress,zero-voltage and zero-current switching.