Transformerless inverters (TIs) are widely used in grid-connected photovoltaic (PV) applications due to their higher efficiency and low cost. However, the absence of galvanic isolation leads to the flow of ground leakage current due to PV parasitics resulting in safety issues and deteriorated power quality. This article proposes a single-phase five-level TI topology with switched diodes and floating capacitors (FCs). The proposed topology employs a lower number of active power switches and has self-voltage-balancing of FCs, voltage boosting ability, and suppressed leakage current complying with the VDE-4105 standard for safety. A suitable modulation strategy is applied to the proposed TI in order to generate a common-mode voltage with a reduced number of voltage swings and transitions yielding in suppressed leakage current. Simulation and experiment results are presented to prove the operability of the proposed TI. A prototype model rated for 1 kW is developed, and the experimental results so obtained are presented. The leakage currents of magnitudes ≈10 and ≈17 mA are obtained in the simulation and experiments, respectively. A detailed comparison with the other similar topologies is presented to attest to the merits of the proposed TI.

中文翻译：

---

一种光伏应用五电平升压逆变器

无变压器逆变器 (TI) 因其更高的效率和低成本而广泛用于并网光伏 (PV) 应用。然而，由于光伏寄生效应，没有电流隔离会导致接地泄漏电流的流动，从而导致安全问题和电能质量恶化。本文提出了一种带有开关二极管和浮动电容器 (FC) 的单相五电平 TI 拓扑。所提议的拓扑采用较少数量的有源电源开关，并具有 FC 的自电压平衡、升压能力和抑制泄漏电流，符合 VDE-4105 安全标准。将合适的调制策略应用于建议的 TI，以生成具有减少的电压摆动和转换数量的共模电压，从而抑制泄漏电流。仿真和实验结果证明了所提出的 TI 的可操作性。开发了一个额定功率为 1 kW 的原型模型，并展示了由此获得的实验结果。分别在模拟和实验中获得了 ≈10 和 ≈17 mA 的泄漏电流。提供了与其他类似拓扑的详细比较，以证明所提议的 TI 的优点。