Experimental-theoretical thermal and electrical analyses of insulated gate bipolar transistors (IGBT) power module

Applications of high-power insulated gate bipolar transistor (IGBT) modules include railway traction, motor drives, and hybrid electric vehicles. The reliability of these semiconductor devices is tightly linked to the operating junction temperatures of IGBT and diode chips present in them. Since these temperatures are very difficult to measure, accurate models and simulation tools are required to compute the instantaneous temperature of the devices under different load conditions. In this paper, we describe a transient 3D heat transfer numerical model of an IGBT power device with many layers of varying cross-sectional areas, distinct materials, and heat sources. Two cases were evaluated according to the total power dissipation considered. In the first case, a nonswitching constant conduction scenario was considered in which a power dissipation of 6.15 W based on experiments was adopted and the calculated results were validated against experimental data obtained via infrared thermography, and excellent agreement between the results was observed. For the second case, IGBT switching - along with power losses due to the gate-closing and gate-opening transitions between conducting and non-conducting states - was taken into consideration. For this case, a higher power of 27.23 W was considered to represent the average power dissipation associated with a typical real-life application of the IGBT unit at a switching at frequency of 1 kHz. For this case, the power dissipation on the IGBT chip was obtained from an electrical simulation and used in the heat transfer problem as a strongly time-dependent heat source. The temperature distributions for both cases were then critically compared.