Fault Diagnosis, Fault Tolerance, and Reconfiguration of Cascaded H-Bridge Multilevel Converter Applications: A Comprehensive Review

Multilevel converter topologies are used in diverse applications requiring medium-voltage and high-power ratings, such as motor drives, power quality compensators, distributed generation, solid-state transformers, and energy storage systems. This paper presents a comprehensive literature review on fault diagnosis, fault tolerance, and reconfiguration schemes applied to cascaded H-bridge multilevel converters (CHB MLCs) in their diverse applications. Since the arrival of multilevel converters, due to the significant increase in components subject to failures, several works have been published covering these topics with the aim of improving the reliability and continuity of operation or to accelerate corrective maintenance. This work summarizes what has been proposed up to June 2026 and visualizes limitations and possible future research directions in these fields. With respect to fault diagnosis, hardware and software schemes are reviewed, along with detection times achieved. On the other hand, diverse fault-tolerance schemes for CHB MLCs are reviewed: from the ones that apply fault-tolerant control to continue operating but at reduced power, to the ones that use auxiliary hardware to perform reconfiguration and restore the pre-fault operation at full power. A discussion of the whole review is presented, and tendencies and possible future directions are formulated. The search scope is limited only to the CHB MLC topology, and the classification criteria is divided into applications such as motor drives, R and RL loads, power quality conditioners, rectifiers, battery energy storage systems, solid-state transformers, and PV systems.