This paper explores a power-conversion system for single-phase transformerless ac module application. A nonisolated high-gain dc–dc stage is coupled with a doubly grounded dynamic dc-link inverter to implement the microinverter topology. The front-end boost stage steps up the single-module voltage to a higher dc voltage, typically to 200 or 400 V as required for the following inverter stage. It is a hybrid of an interleaved boost and switched capacitor concept capable of achieving high gain while simultaneously maintaining reduced voltage and current stress, and thus lowering switching and conduction loss for most of the switches. By directly connecting the grid neutral to the photovoltaic (PV) negative, the doubly grounded voltage swing inverter has the advantage of zero capacitive-coupled common-mode ground currents, critical for transformerless PV inverters. The two dc links of the inverter stage share the double-line frequency power decoupling with a combination of higher value of mean voltage and relatively large 120-Hz ripple component–the dynamic dc-link approach. Through an optimization algorithm, the decoupling capacitance is minimized enabling an all-film capacitor implementation while satisfying the converter's operating constraints over a wide range of power factors. The simulation as well as experimental results from a GaN-based hardware prototype validate the converter's performance.

中文翻译：

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用于带有源功率去耦的交流模块应用的高升压无变压器逆变器

本文探讨了一种用于单相无变压器交流模块应用的电源转换系统。非隔离式高增益 DC-DC 级与双接地动态 DC 链路逆变器耦合以实现微型逆变器拓扑。前端升压级将单模块电压升至更高的直流电压，通常为 200 或 400 V，以满足后续逆变器级的要求。它是交错升压和开关电容器概念的混合体，能够实现高增益，同时保持降低的电压和电流应力，从而降低大多数开关的开关和传导损耗。通过将电网中性线直接连接到光伏 (PV) 负极，双接地电压摆幅逆变器具有电容耦合共模接地电流为零的优点，无变压器光伏逆变器的关键。逆变器级的两个直流链路共享双线频率功率去耦，结合较高的平均电压值和相对较大的 120 Hz 纹波分量——动态直流链路方法。通过优化算法，去耦电容被最小化，从而实现全薄膜电容器的实现，同时满足转换器在宽功率因数范围内的操作约束。来自基于 GaN 的硬件原型的仿真和实验结果验证了转换器的性能。去耦电容最小化，可实现全薄膜电容器，同时满足转换器在宽功率因数范围内的操作限制。来自基于 GaN 的硬件原型的仿真和实验结果验证了转换器的性能。去耦电容最小化，可实现全薄膜电容器，同时满足转换器在宽功率因数范围内的操作限制。来自基于 GaN 的硬件原型的仿真和实验结果验证了转换器的性能。