隔离型双半桥DC-DC变换器的软开关特性

摘要

分析了隔离型双半桥(DHB)DC-DC变换器的软开关特性.首先介绍DHB变换器的工作原理,详细分析DHB变换器的软开关过程.通过理论建模和定量分析,给出各开关管实现零电压开通的充要条件.总结谐振电流、变换器输出功率和死区时间与实现零电压开通的三条规律,推导出各开关管软开关实现所允许的变换器最小输出功率的解析表达式.然后,提出一种改进的占空比控制策略,有效地扩宽了变换器的软开关运行范围,有助于变换器实现稳定的软开关运行.最后,通过样机实验验证了所提的理论分析以及改进控制方法的正确性和有效性.%This papermainly discusses the dual-half-bridge (DHB) DC-DC converter. First, the operation principle of DHB is introduced and the possible switching processes are analyzed in details. Then, two soft-switching conditions of each switch are given. Moreover, three principles of the resonant current, output power and dead time are summarized. The minimum output power to realize the soft switching is derived. Finally, an improved control technique is proposed to extend the soft-switching range. The experimental results verify the theoretical analysis and the proposed control technique.