A prognostic approach for non-punch through and field stop IGBTs

Development of prognostic approaches for insulated gate bipolar transistors (IGBTs) is of interest in order to improve availability, reduce downtime, and prevent failures of power electronics. In this study, a prognostic approach was developed to identify anomalous behavior in non-punch through (NPT) and field stop (FS) IGBTs and predict their remaining useful life. NPT and FS IGBTs were subjected to electrical–thermal stresses until their failure. X-ray analysis performed before and after the stress tests revealed degradation in the die attach. The gate–emitter voltage (VGE), collector–emitter voltage (VCE), collector–emitter current (ICE), and case temperature were monitored in situ during the experiment. The on-state collector–emitter voltage (VCE(ON)) increased and the on-state collector–emitter current (ICE(ON)) decreased during the test. A Mahalanobis distance (MD) approach was implemented using the VCE(ON) and ICE(ON) parameters for anomaly detection. Upon anomaly detection, the particle filter algorithm was triggered to predict the remaining useful life of the IGBT. The system model for the particle filter was obtained by a least squares regression of the VCE(ON) at the mean test temperature. The failure threshold was defined as a 20% increase in VCE(ON). The particle filter approach, developed using the system model based on the VCE(ON), was demonstrated to provide mean time to failure estimates of IGBT remaining useful life with an error of approximately 20% at the time of anomaly detection.