Transient temperature measurements and modeling of IGBT's undershort circuit

摘要

This paper discusses the estimation of possible device destructionninside power converters in order to predict failures by means ofnsimulation. The study of insulated gate bipolar transistor (IGBT)nthermal destruction under short circuits is investigated. An easynexperimental method is presented to estimate the temperature decay innthe device from the saturation current response at low gate-to-sourcenvoltage during the cooling phase. A comparison with other classicalnexperimental methods is given. Three one-dimensional thermal models arenalso studied: the first is a thermal equivalent circuit represented bynseries of resistance-capacitance cells; the second treats thendiscretized heat-diffusion equation; and the third is an analyticalnmodel developed by building an internal approximation of thenheat-diffusion problem. It is shown that the critical temperature of thendevice just before destruction is larger than the intrinsic temperature,nwhich is the temperature at which the semiconductor becomes intrinsic.nThe estimated critical temperature is above 1050 K, so it is much highernthan the intrinsic temperature (~550 K). The latter value isnunderestimated when multidimensional phenomena are not taken intonaccount. The study is completed by results showing the threshold voltagenand the saturation current degradation when the IGBT is submitted to anstress (repetitive short circuit)