Transformerless inverters (TIs) are widespread in photovoltaic (PV) applications due to their low cost and high efficiency. However, TIs suffer due to leakage current as a consequence of PV parasitic capacitance, and high-frequency common-mode voltage, which has resulted in the emergence of several topological and control scheme modifications. In this article, a switched-capacitor (SC) based inverter capable of synthesizing a five-level voltage is proposed. In the devised structure, the negative pole of the dc bus is directly connected to the grid neutral, thereby resulting in zero leakage current. In addition, industrial standard half-bridge modules can be employed directly for implementing the proposed inverter without modifications, making it more practically feasible. The proposed topology has the capability of self-voltage balancing of SC, reactive power processing, and full dc-bus utilization as opposed to half-bridge topologies. The principle of operation and a simple logic-gate-based pulse generation scheme is presented in detail. Simulation and experimental results confirming the practical viability of the proposed topology are presented. Finally, the superior features and the merits of the proposed topology are shown through a detailed comparison against state-of-the-art topologies.

中文翻译：

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完全利用直流母线的共地型五电平无变压器逆变器拓扑结构

无变压器逆变器 (TI) 因其低成本和高效率而广泛应用于光伏 (PV) 应用中。然而，由于 PV 寄生电容和高频共模电压导致漏电流，TI 会受到影响，这导致出现了几种拓扑和控制方案修改。在本文中，提出了一种能够合成五电平电压的基于开关电容器 (SC) 的逆变器。在设计的结构中，直流母线的负极直接连接到电网中性点，从而导致零泄漏电流。此外，无需修改即可直接采用工业标准半桥模块来实现所提出的逆变器，使其更具实际可行性。所提出的拓扑具有 SC 的自电压平衡能力，无功功率处理，以及与半桥拓扑不同的完全直流总线利用率。详细介绍了工作原理和简单的基于逻辑门的脉冲生成方案。模拟和实验结果证实了所提出的拓扑结构的实际可行性。最后，通过与最先进拓扑的详细比较，展示了所提出拓扑的优越特性和优点。