A Comprehensive Review of Fault-Tolerant Non-Isolated DC–DC Converters for Critical Applications: Active and Passive Redundancy Approaches

Reliability in most of the power converters used in critical applications is achieved by incorporating fault-tolerance features. In this paper, various fault-tolerant dc-dc converters proposed with active and inactive redundancy are reviewed and compared to gain an understanding of the prominent solutions. Guidelines for the selection of a fuse are presented with computation for various input switching current waveforms. Various fault-tolerant configuration with active redundancy is derived and discussed. Multiport DC–DC converters inherently exhibit fault-tolerant characteristics owing to the availability and flexible utilization of multiple input sources. This paper presents an overview of selected converter topologies in which component-level redundancy is strategically employed to enhance reliability and fault tolerance. In addition, relevant IEEE and IEC codes and standards for diverse applications are examined, with a particular focus on protection and safety requirements. This study also emphasizes the need of proactive adherence to standards and codes to address the protection mechanisms and avoid fault occurrences, thereby ensuring reliable operation. Moreover, the study identifies the fault-prone elements within critical power-conditioning converter components. Experimental results of a fault-tolerant quadratic boost converter with 2-level redundancy are presented. This article will offer valuable design guidelines for researchers working in this area to enhance the reliability of high-gain dc-dc converters. In conclusion, key open research challenges and several recommendations for future research analysis are emphasized.