In a high step-up converter, the primary side input current contributes a significant share of total power loss. Meanwhile, high-voltage stresses of secondary side components are also big issues. This study proposes an isolated converter with secondary side quasi-resonant loops. The push–pull structure is adopted to reduce active switch numbers so the primary side power loss can be controlled in a very minor range. The newly added resonant loops on the secondary side significantly decrease the current stresses of the resonant capacitors, so the power loss caused by capacitor equivalent-series-resistance is reduced. The voltage stresses of diodes and capacitors on the secondary side are also decreased by an improved symmetrical-voltage-quadrupler-rectifier structure. The proposed converter is with the maximum voltage gain equal to 4 without consideration of the transformer. Therefore, it is helpful to decrease the transformer turns ratio. The operation process is analysed in detail and the design considerations are also summarised. Theoretical analysis is verified by the experimental results of a 400 W prototype with 34–40 V input and 380 V output.

中文翻译：

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基于次级侧准谐振回路的隔离式高升压转换器的分析与设计

在高升压转换器中，初级侧输入电流占总功耗的很大一部分。同时，次级侧组件的高压应力也是一个大问题。这项研究提出了一种具有次级侧准谐振环路的隔离转换器。采用推挽结构来减少有源开关的数量，因此初级侧功率损耗可以控制在很小的范围内。在次级侧新添加的谐振环路显着降低了谐振电容器的电流应力，因此减少了由电容器等效串联电阻引起的功率损耗。通过改进的对称电压-四倍整流器-整流器结构，还可以减小次级侧上的二极管和电容器的电压应力。建议的转换器在不考虑变压器的情况下具有等于4的最大电压增益。因此，降低变压器匝数比是有帮助的。详细分析了操作过程，并总结了设计注意事项。理论分析通过具有34–40 V输入和380 V输出的400 W原型的实验结果得到验证。