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In this article, a novel reliability evaluation scheme to achieve quantitative reliability calculation for power converter in the whole operation region of switched reluctance motor system is proposed. First, the electrical model is built to obtain electrical stress and fault-tolerance capability in the Matlab/Simulink environment. Second, the thermal circuit model is performed to get the thermal stress of power converter quickly. Third, the dynamical Markov model with a novel failure criterion is applied to achieve quantitative reliability calculation by characterizing the fault-tolerance capability and thermal stress. The proposed failure criterion can simplify the model to decrease the number of states and avoid the divergence of results, especially the interconnected relationship between the three models is key emphasized. Next, the proposed reliability evaluation scheme is carried out to explore the reliability of power converter under different chopping modes. Finally, simulations in conjunction with experiment verify the validity of the proposed reliability evaluation scheme.

The fault diagnosis methods and remediation strategies (RSs) are critical for high-reliability operation of power converters in switched reluctance motor drive (SRD). This study presents an online sensorless fault diagnosis method and effectively selects the RSs from the reliability view. To begin with, the equations of neutral voltage are derived for each phase leg in popular asymmetric half-bridge converter under normal and faulty operation conditions. Next, the diagnosis criterion is proposed with the combination of drive signals and neutral voltage signatures. Besides, the low-cost circuits are designed to save the diagnosis cost, especially for the control strategies without any current or voltage sensor. Moreover, the diagnosis time can be decreased to 7 μs and not affected by the speed, load torque, control strategies and topologies. Moreover, the proposed method can also identify the multiple faults of transistors. In addition, to further enhance the reliability of power converter and then for SRD, the reliability-oriented selection of RSs is carried out by means of the dynamic Markov model. Finally, the experiments of fault diagnosis and thermal stress measurement are conducted to confirm the effectiveness of the proposed diagnosis method and RSs selection.