中文摘要：

在光伏并网发电系统中,无输出隔离变压器全桥逆变器高效率特性得到广泛应用,但该拓扑并网时不能有效地消除直流注入。由于各种扰动源的扰动本质均反映为逆变器开关侧输出电压的直流扰动,文章用一个集中的扰动源代替各种分散扰动,并建立了各种直流扰动源的数学模型。为了有效抑制输出电压直流扰动,用逆变桥开关侧输出电压中直流分量反馈构成闭环控制系统。最后在3 k W实验样机上进行了直流抑制实验,实验结果验证了文章所提方法的有效性。

英文摘要：

Due to high efficiency performance, full-bridge inverter without output isolation transformer is widely used in grid-connected photovoltaic system. However, it can＇t eliminate DC current injection validly. An analysis shows that all distributed disturbance sources only lead to a DC bias of output voltage at the inverter switch side, so a centralized disturbance source is presented instead of all of the disturbances, and its mathematical models that simulates all kinds of DC disturbance features are established. In order to effectively eliminate DC bias of output voltage,a closed loop control system is established with a feedback of the DC component of output voltage at the inverter switch side. Finally, the proposed control strategy is tested on a 3 k W inverter, the experimental results prove the validity of the control strategy.