Experimental validation of IGBT thermal impedances from voltage-based and direct temperature measurements

Abstract

Temperature measurement on IGBT modules using voltage-based, direct and infrared methods is presented. The measured temperatures from all three methods are used in determining thermal impedances of IGBT and diodes for air cooled IGBT modules at different air flowrates. Thermal impedances for both active and passive switching elements are measured and the corresponding Foster network is established. The measured temperature and corresponding thermal impedances calculated from measured temperatures using the direct and voltage-based temperature measurement approach are validated using infrared temperature measurements and corresponding thermal impedances calculated from infrared measured temperatures. Finally, thermal impedances calculated from maximum measured IGBT and diode temperatures are compared to those obtained from measured average IGBT and diode temperatures.