For photovoltaic applications, the flyback microinverter with pseudo-dc-link is popular as a simple topology but brings large transformer turns ratio and thus large leakage inductance, which would deteriorate the converter efficiency. To solve this issue, based on the nonisolated pseudo-dc-link structure, this paper proposed a hybrid boost–flyback/flyback (BF/F) microinverter. This new topology is operated at the BF mode for the most segment of a half grid cycle and the F mode for the rest. During the BF mode, high voltage gain with low voltage stress is easily available in minimized transformer turns ratio. Besides, the leakage energy is recycled and the turn-off voltage spike of the main switch is clamped, as a result of a passive snubber inherently contained in this mode. Given that the BF mode is lack of step-down function, the F mode is developed to regulate the output voltage even for values lower than the input voltage. The operation and characteristic of the hybrid BF/F microinverter in boundary conduction mode are analyzed in detail, and the mathematical expression of reference current is derived theoretically to guarantee high power quality. Finally, a 240 W prototype was implemented to validate the theoretical analysis and the benefits of the proposed topology.

中文翻译：

---

一种用于光伏应用的混合升压-反激/反激微型逆变器

对于光伏应用，具有伪直流链路的反激式微型逆变器作为一种简单的拓扑结构很受欢迎，但会带来较大的变压器匝数比和较大的漏电感，这会降低转换器效率。为了解决这个问题，本文基于非隔离伪直流链路结构，提出了一种混合升压-反激/反激（BF/F）微型逆变器。这种新拓扑在半个电网周期的大部分时间段以 BF 模式运行，其余时间段以 F 模式运行。在 BF 模式期间，可以在最小的变压器匝数比下轻松获得具有低电压应力的高电压增益。此外，由于该模式中固有的无源缓冲器，泄漏能量被回收并且主开关的关断电压尖峰被钳位。鉴于BF模式缺乏降压功能，F 模式旨在调节输出电压，即使值低于输入电压。详细分析了边界导通模式下混合BF/F微型逆变器的运行和特性，从理论上推导出参考电流的数学表达式，以保证高电能质量。最后，实现了 240 W 原型以验证理论分析和所提议拓扑的优势。