Power Converter's IGBT Multi‐State Reliability Analysis for Low Failure Rate Operation

ABSTRACT Switching devices, the most vulnerable component within converters, underscores the critical need to enhance their reliability and prolong the power converter's lifetime. This paper proposes a multi‐state reliability model for insulated gate bipolar transistors (IGBTs) that departs from conventional two‐stage models with constant failure rate. Moreover, it quantifies the effect of DC‐link voltage on IGBT reliability for switching frequencies below 5 kHz and derives an operating voltage ratio envelope of about 60% of the rated voltage. Operating within this band maximises lifetime and reduces maintenance cost, providing a practical voltage reference for control strategies. Finally, Monte Carlo simulations across multiple cases verify the feasibility and robustness of the proposed model and comparative hardware experiments support the underlying thermal assumptions of the proposed model.