中文摘要：

分析了非隔离光伏并网逆变系统的地电流大小。介绍了包括单级结构的传统三相逆变器和三相半桥逆变器,以及两级结构的带2电平升压变换器的三相逆变器和带3电平升压变换器的三相逆变器。建立了地电流解析计算方法,给出了各种拓扑的共模简化模型及地电流的傅里叶表达式,以及参数变化对地电流的影响。分析了不同前级升压拓扑对地电流的影响,进行了仿真和实验。

英文摘要：

The ground current for grid connected transformerless photovoltaic inverter system is analyzed. For the single-stage structure, the traditional three phase inverter and the three phase half-bridge inverter with split capacitor are discussed. For the two-stage structure, the two-level boost converter plus threephase inverter and the three-level boost converter plus three-phase inverter are discussed. The calculation method to estimate the ground current is established. The common-mode models and the Fourier equations of the ground current are given. And the effect of different parameters on the ground current is proposed. The influence of different front-end boost converters on the ground current is analyzed. The simulation and experiment results are given to verify it.