Effect of Input Power Interruptions on Power Electronics Reliability

Reliability demands for products in power electronics have increased as the desired lifetime of high reliability products has been raised from ten to even thirty years. Increased lifetime and reliability demands along with decreasing time to market have also affected the reliability testing needed for such products. To achieve more accurate reliability results in less time, combined stress testing methods have attracted more attention in recent studies. In this paper, accelerated reliability testing using combined stress testing method was conducted on commercial motor drives. The motor drives were tested in high temperature and high humidity test combined with power cycling. Additionally, input power interruption was included in part of the tests. The aim of this research was to study the effect of input power interruptions on failure times and failure modes. The results from the tests show clear differences between tests conducted either with or without input power interruptions. Shorter failure times were achieved when input power interruptions were included in the test procedure. However, they also changed the failure modes between the tests. As a conclusion, the different test methods reported in this study accelerated different failure mechanisms. Consequently, if power interruptions are used in testing, power interruption parameters and the relevance of failure modes occurring in accelerated testing compared to those seen in actual use conditions should be considered carefully.