中文摘要：

提出了一种基于有向图论分析的电力电子变换器结构性故障诊断方法。首先将变换器的拓扑图转换为有向图，找到正常工作路径；然后根据故障类型求出邻接矩阵，利用邻接矩阵得到故障时的工作路径，与正常工作路径进行比较后，可以得到特征电量的变化情况，从而获得故障诊断的判据。文中以二极管钳位型三电平半桥逆变器为例，介绍了基于有向图论分析的结构性故障分析及诊断方法，最后通过仿真验证了该方法的可行性和有效性。

英文摘要：

A structural fault diagnosis method of power electronic converter based on the directed graph theory was proposed. First, the power converter topology was converted into the directed graph to find out the normal working paths. Second, according to the type of failure, the fault working paths were obtained by the adjacency matrix. Next, by comparing the fault working paths with normal ones, the status of characteristic electric quantities were derived, which can be used for the fault diagnosis criteria. And then the feasibility and validity of the proposed method were verified by simulating a three-level diode- clamped half-bridge inverter.