A new fundamental structure of a single-phase transformer-less grid connected multilevel inverter based on a switched-capacitor structure is presented in this study. By employing the series-parallel switching conversion of the integrated switched-capacitor module in a packed unit, attractive features for the proposed inverter can be obtained such as high efficiency and boosting ability within a single stage operation. Also, using a common grounding technique provides an additional advantage of reducing the leakage current. Moreover, the presented structure generates a multilevel waveform at the output voltage terminals which reduces the harmonics in the system. A peak current controller is utilized for triggering the gate of the power switches and controlling both the active and reactive powers. This results in a tightly controlled current with an appropriate quality that can be injected to the grid using a single source renewable energy resource. Operating procedures, design considerations, comparison studies and test results of a 620 W prototype are also presented to validate the accuracy and feasibility of the proposed multilevel inverter.

中文翻译：

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一种用于光伏应用的新型无变压器五电平并网逆变器

本研究提出了一种基于开关电容器结构的单相无变压器并网多电平逆变器的新基本结构。通过在封装单元中采用集成开关电容器模块的串并联开关转换，可以获得所提出的逆变器的有吸引力的特性，例如在单级操作中的高效率和升压能力。此外，使用公共接地技术还提供了减少漏电流的额外优势。此外，所提出的结构在输出电压端子处生成多电平波形，从而减少系统中的谐波。峰值电流控制器用于触发功率开关的栅极并控制有功和无功功率。这会产生具有适当质量的严格控制的电流，可以使用单一来源的可再生能源将其注入电网。还介绍了 620 W 原型的操作程序、设计考虑、比较研究和测试结果，以验证所提议的多电平逆变器的准确性和可行性。