应用于宽输入电压范围的两模式切换型软开关谐振直流变换器

A Two-Mode Soft-Switching Resonant DC-DC Converter for Wide Input Voltage Range Applications

该文提出一种具有两模式切换运行特性的软开关谐振型直流变换器,通过控制辅助开关管的通断,来改变谐振腔结构进而决定变换器的运行模式。该变换器共有两种工作模式:LLC模式和LLCC模式。结合LLC谐振变换器的参数设计方法及所提变换器的特点,设计出可以同时满足两种运行模式要求的参数。通过对模式切换点进行优化选择,变换器可以在较窄的频率范围内同时实现高效率和宽增益范围的目标。另外,在不增加拓扑复杂度的基础上引入额外的谐振零点,实现了内在的过电流保护功能。最后,搭建一台1kW的实验样机来验证上述理论分析的正确性。实验结果表明:所提变换器具有优良的性能,当输入电压从150~400V变化时,输出电压一直稳定在400V,所测最高效率值为97.3%。

A two-mode soft-switching resonant DC-DC converter is proposed in this paper.The resonant structure is changed by controlling the auxiliary switch,and thus the operating modes are determined.There are two working modes in total,namely LLC mode and LLCC mode.Combining the traditional parameter design of the LLC converter and the characteristics of the proposed converter,a novel parameter process that can meet the requirements of the two modes is designed.Moreover,by optimizing the switching point,the converter can achieve high efficiency and wide gain range within a narrow frequency range.In addition,an extra resonant zero point is introduced without increasing the complexity of the topology.As a result,the inherent over-current protection is guaranteed.Finally,a 1kW prototype is built to verify the correctness of the above theoretical analysis.The experimental results show that the proposed converter has excellent performance.When the input voltage varies from 150V to 400V,the output voltage remains constant at 400V and the maximum efficiency is 97.3%.