Prognostics for electronics components of avionics - NASA IGBT accelerated ageing case study

Insulate gate bipolar transistors (IGBTs) are widely used in electric vehicles, railway locomotive and new generation aircrafts, due to the IGBTs have advantages in small conduction resistance and small drive current. Hence, the reliability of IGBTs directly affect the reliability and performance of these vehicle systems. In recent years, a series of research works about IGBT reliability, failure mode and ageing analysis have been carried out widely, and a suitable prognostics method for IGBT and an efficient algorithm for predicting the IGBT Remaining Useful Life (RUL) become increasingly important. In recent years, despite the research works on IGBT reliability, failure mode and effect analysis are carried out widely, the prognostics and prediction of the IGBT remaining useful life are still the bottleneck in the research work to develop IGBT health management system. In this thesis, a framework and algorithm of IGBT prognostics and RUL prediction were developed. The research was based on the IGBT accelerated ageing experiments. The IGBT ageing data were processed and analysed, and the mechanism of the IGBT degeneration was studied. Additionally, the IGBT degradation models were built to simulate the IGBT degeneration process which were utilised to develop the prognostics algorithm for predicting the IGBT RUL. Gamma distribution model, Exponential distribution model, Poisson distribution model and the combining distribution model were established, and Monte Carlo simulation was utilised in the algorithm to compute the IGBT remaining useful life. The collector emitter voltage (VCE) was used as precursor parameter in prognosis to predict the RUL. Seven IGBTs were experimented in this prognostics research. The RUL prediction results were analysed and compared, and the prognostics algorithm was developed and summarised. The accuracy of the RUL prediction was presented, and the root mean square error was utilised to analyse and compare the efficiency and applicability of different models. The study of the IGBT prognostics and algorithm development were summarised and demonstrated.