Reliability Analysis on Power Converter of Switched Reluctance Machine System Under Different Control Strategies

In this paper, a novel reliability assessment scheme is presented to achieve the optimal selection of control strategies for switched reluctance machine system from the perspective of reliability. To begin with, a combination model of k-out-of-n:G model and Markov model is proposed to lower the complexity and enhance the accuracy of system-level reliability assessment. As for the component-level reliability assessment, the three-dimensional coupled thermal circuit model of power converter is built to achieve the precise and fast prediction of junction temperature that is necessary for calculation of failure rate. Then the static and dynamic reliability analyses are carried out under voltage chopping control (VCC), current chopping control (CCC), and angle position control (APC) strategies, which indicates that the implementation scope of the APC strategy should be broadened. Compared with the VCC strategy, the CCC strategy is strongly recommended even if current sensors boost the extra failure rate. Besides, the increase in redundancy levels on power converter is certified as the most powerful measure for reliability enhancement of the SRM system and the most cost-effective redundancy level can also be quantitatively obtained. The experiments of fault-tolerance capability and thermal stress indirectly verify the validity of reliability analysis.