In situ Condition Monitoring of IGBTs Based on the Miller Plateau Duration

Aging precursor identification is crucial to achieving online condition monitoring and estimating the remaining lifetime of insulated-gate bipolar transistors (IGBTs). However, existing failure precursors are limited with respect to in situ monitoring. In this paper, the duration of the Miller plateau during the IGBT turn-on transition is proposed as an online precursor indicating two dominant types of failures. Based on the theoretical closed-form expressions, the adverse effects of package-related bond wire fatigue and chip-related gate oxide degradation on the Miller plateau duration are explained. By using a dedicated online measurement system that is implemented on the gate driver side, the proposed precursor is extracted during operation. Discrete IGBTs of two gate structures are employed during the accelerated aging tests. Negative and positive degradation trends of the Miller plateau duration under power cycling and high electric field stress, respectively, are revealed, thus illustrating the validity of the proposed method. Finally, the main differences in physics-of-failure between two types of aged devices are investigated using post-failure analysis. The innovation of applying the Miller plateau duration as a failure precursor involves its ability to accomplish real-time field monitoring and its sensitivity to multiple failure mechanisms.