Active neutral-point-clamped converter adds open-circuit fault-tolerant (OCFT) capability compared with the widely used original neutral-point-clamped (NPC) topology. However, such capability is hard to utilize due to difficulties in pulse-width modulation (PWM) design and the randomness of failure points, particularly in high-level converters. Current research mainly focused on low-level topologies with a limited number of fault scenarios; moreover, the analysis and design are performed in a nonsystematic way. In this article, the OCFT operations of active NPC (ANPC) converters with multiple fault switches are investigated and the systematic PWM design process is proposed. First, different matrices are proposed for the ANPC converters to capture the complicated topology information and achieve an exhaustive analysis of the topological redundancy. Then, a step-by-step process is proposed to derive the suitable OCFT PWM patterns. The five-level ANPC converter is investigated as an example. Its experimental results validate that the proposed approach can 1) properly predict the behavior of converters systematically so that the tolerable faults and intolerable can be identified during the design procedure, and 2) the inherent fault-tolerant capability of the five-level ANPC converter can be guaranteed through the proposed method, and 3) multiswitch open-circuit faults can be easily dealt with by implementing suitable carrier-based PWM schemes.

中文翻译：

---

基于矩阵的有源中性点钳位转换器的开路容错分析和 PWM 设计方法

与广泛使用的原始中点钳位 (NPC) 拓扑相比，有源中点钳位转换器增加了开路容错 (OCFT) 能力。然而，由于脉宽调制 (PWM) 设计的困难和故障点的随机性，这种能力很难利用，特别是在高电平转换器中。目前的研究主要集中在故障场景数量有限的低级拓扑上；此外，分析和设计是以非系统的方式进行的。在本文中，研究了具有多个故障开关的有源 NPC (ANPC) 转换器的 OCFT 操作，并提出了系统的 PWM 设计过程。首先，为ANPC转换器提出了不同的矩阵来捕获复杂的拓扑信息并实现对拓扑冗余的详尽分析。然后，提出了一个逐步的过程来推导出合适的 OCFT PWM 模式。以五电平ANPC变流器为例进行研究。其实验结果验证了所提出的方法可以：1）系统地正确预测转换器的行为，以便在设计过程中识别出可容忍的故障和不可容忍的故障，2）五电平 ANPC 转换器的固有容错能力可以3）通过实施合适的基于载波的 PWM 方案可以很容易地处理多开关开路故障。