中文摘要：

从调制策略和结构选择角度出发，研究了级联型变频器故障容错问题。通过改变调制信号幅值与相位差。给出一种新型载波调制容错策略。建立单元模块可靠度及容错变频器可靠度kin（G）模型，根据k/n（G）模型定量计算容错变频器可靠度，进而给出了容错拓扑结构优化选择方法。最后通过实例分析与计算，验证所提方法有效可行。

英文摘要：

In view of modulation strategy and structure selection for converters, the fault-tolerant issues of cascade con- verters is studied.A new fauh-tolerant method is proposed based on carried modulation by varying the amplitude and phase of modulation signal.The reliability model of the modules is built,and then the k/n（G） model is built for the fault- tolerant converter.According to the k/n（G） model, the reliability of the fault-tolerant inverter is calculated and a topology structural optimization method is proposed.At last, the feasibility of the proposed converters is validated by examples.