In trasformerless grid-connected photovoltaic (PV) systems, common-mode voltage (CMV) fluctuations cause leakage current flow through the stray capacitance of the PV panels. Shoot-through states in a quasi-Z-source inverter (q-ZSI) increase the amplitude of high-order harmonics of CMV. In this paper, by using the modulation technique based on odd pulse width modulation and minor change in the Z network of the three-phase q-ZSI, the leakage current is blocked. No extra semiconductor element is added. By the proposed technique, CMV is kept nearly constant during switching cycles. The experimental results for CMV analysis in a $\text{1}\;{\text{kW}}$ prototype are presented to verify the theoretical analysis.

中文翻译：

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用于光伏应用的具有恒定共模电压的三相准 Z 源逆变器

在无变压器并网光伏 (PV) 系统中，共模电压 (CMV) 波动会导致漏电流流过光伏面板的杂散电容。准 Z 源逆变器 (q-ZSI) 中的直通状态会增加 CMV 高次谐波的幅度。本文采用基于奇数脉宽调制和三相q-ZSI Z网络微小变化的调制技术来阻断漏电流。没有添加额外的半导体元素。通过所提出的技术，CMV 在开关周期期间几乎保持恒定。给出了在 $\text{1}\;{\text{kW}}$ 原型中进行 CMV 分析的实验结果以验证理论分析。