中文摘要：

为了在满足并网约束条件的前提下拓展光伏电池的并网发电范围以及提高系统的欧洲效率,以提高光伏并网逆变系统的利用率,提出新的在线拓扑可变型并网逆变技术。通过在级联型多电平逆变器中增加双向切换开关,使其在光伏电池输出电压/功率较低时工作于级联模式,而在输出电压/功率较高时切换为H桥逆变器模式,从而实现只采用单级逆变结构即可获得较宽的并网发电范围和提高逆变器欧洲效率。给出了基于5电平级联型逆变器的在线拓扑可变型并网逆变器的具体结构及详细的实验结果,以验证所提出方案的正确性。

英文摘要：

A scheme of grid-connected inverter with online variable topology is proposed to extend the generation range of PV array and increase the European efficiency and utilization rate of PV grid-connected inverter system in the condition of grid-connection constraints. An additional bidirectional power switch is applied to make the cascaded multilevel inverter operate in the cascading mode when the output voltage /power of PV array is lower,otherwise in the H-bridge mode,which,with the single-stage inversion structure only,widens the generation range and increases the European efficiency. The detailed structure of grid-connected inverter with online variable topology is designed based on the cascaded five-level inverter and the correctness of the proposed scheme is verified by the experimental results.