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针对常规半桥型模块化多电平换流器无法隔离直流故障电流的问题，提出一种新型的应用于模块化多电平换流器的自阻型子模块拓扑，并列出自阻型子模块的4种结构。这4种类型的自阻型子模块在隔离直流故障电流时，需要同时闭锁IGBT的触发脉冲。为了降低触发同时性的要求，进一步提出无需同时闭锁IGBT触发脉冲的2种增强自阻型子模块拓扑。模块化多电平换流器技术(modular multilevel converters，MMC)的全部子模块采用增强型子模块时所使用的电力电子器件较多，为了进一步减少MMC中电力电子器件的数量，提出一种由增强型子模块和常规半桥子模块构成的混合型MMC。PSCAD/EMTDC下的仿真研究表明，所提出的自阻型子模块、增强型子模块及混合型换流器能有效隔离直流故障。相比于常规半桥型MMC，该混合型MMC仅需提高25%的IGBT即可具备隔离直流故障电流的功能，因此具有良好的工业应用价值。“,”To solve the problem that traditional MMC based on half-bridge sub-module being incapable of isolating dc fault current, a new topology of self-blocking sub-module is proposed in this paper. Four types of self-blocking sub-modules that require simultaneously blocking the IGBTs are firstly proposed. To eliminate the requirements on simultaneously blocking, two types of enhanced self-blocking sub-modules are further proposed. To further reduce the used power electronic devices, a hybrid converter combines enhanced self-blocking sub-modules with traditional half bridge sub-modules is then proposed. Feasibility of the proposed sub modules and hybrid converter are verified by simulations in PSCAD/EMTDC. The proposed hybrid converter is able to isolate dc fault current with only 25% increase of the used power electronic device compared with traditional half-bridge cell MMC which is not able to isolate dc fault current.