A Comparative Study of Numerical Methods for IGBT Junction Temperature Estimation

The insulated gate bipolar transistor is highly utilized in a wide range of applications due to its several advantages compared to other types of transistors like high voltage capacity and low power dissipation. The problem encountered with the IGBT transistor lies in its high cost and especially its vulnerability to failure due to high temperature which derates the device's electrical characteristics and thus accelerates aging. The power module's reliability is considered as the key factor affected by the junction temperature. For this reason, the measurement of IGBT junction temperature is of prior interest to perform thermal management. This paper presents two numerical ways for junction temperature determination, the first one is based on a numerical estimation using a one-dimensional finite-difference method. To perform an accurate simulation, the properties of the various existing IGBT layers were determined using X-ray dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). Further, a program using datasheet information was developed to determine the RC thermal parameters and used to provide temperature variation over time and a heat spreading model inside the IGBT layers. Finally, a good agreement was found between the numerical results obtained from the proposed models.