Comprehensive Reliability Review and Assessment of Z-Source Step-Up DC-DC Converters

The Z-source (ZS) or Quasi-ZS converters are among the popular DC-DC converters that employ impedance networks to enable a wide output voltage range and step-up capability. These converters typically offer low normalized (per-unit) voltage stress across components. In recent years, a variety of improved ZS topologies have been proposed, offering enhancements over the conventional design. The previously published articles present extensive studies analyzing ZS converters from multiple perspectives, including component count, step-up/down capability, voltage stress, source current characteristics (pulsating or non-pulsating), common ground availability, duty cycle range, efficiency, cost, and power density. However, reliability analysis of these converters has received relatively little attention. This study expresses comprehensive reliability review and assessment on popular traditional and developed ZS topologies. Moreover, the effect of changes in each of design or operational parameters on converters' reliability and Mean Time to Failure as well as components' failure rate and the sensitivity of components' failure rate have been studied. The results contribute to the optimal sizing of design and operational parameters to enhance component lifetime and guarantee the converter's maximum reliability. The validity of the theoretical analysis is confirmed through experimental thermal testing.