中文摘要：

提出一种基于二极管无源钳位思想的单相无变压器型光伏并网逆变器拓扑。与H5等传统电路相比，本拓扑具有更好的对地漏电流抑制能力。目前主流的单相无变压器型逆变电路普遍采用直流或交流解耦技术，阻断共模电流的流通路径。但是，功率开关上的寄生电容可能与共模电抗形成谐振回路，使得共模电流无法彻底消除。以H5拓扑为例，定量分析功率器件寄生电容影响共模电流的机理。针对这一问题，引入无源二极管钳位电路，使得共模电压被母线电容中点钳位，从而抑制了功率器件寄生电容引起的共模电压振荡，更有效地消除对地漏电流。在理论和仿真分析的基础上，通过搭建2 kW实验平台验证所提拓扑的性能。结果表明，改进拓扑相对于原拓扑而言，能更好地抑制对地漏电流，提高了无变压器型光伏并网系统的安全裕度。

英文摘要：

A single-phase transformerless grid-connected photovoltaic （PV） inverter topology was proposed based on diode clamped method. The proposed circuit provides an effective improvement in common-mode current rejection capability, compared with state-of-the-art dc/ac decoupled solutions such as the H5 topology. In the proposed method, an extra voltage clamped path is inserted in an ac-decoupled transformerless inverter through two passive diodes. As a result, the common-mode voltage is clamped by the dc capacitor to eliminate the possible high-frequency common-mode oscillations caused by power device parasitic capacitors, which is the major cause of leakage current in dc/ac decoupled transformerless topologies. The proposed passive clamped technique features cost effective solution with no additional active switches, in comparison with the active clamping counterpart. The performance of the proposed topology has been verified by simulation and experiment with a 2kW prototype.