TRANSIENT TEMPERATURE-MEASUREMENTS AND MODELING OF IGBTS UNDER SHORT-CIRCUIT

This paper discusses the estimation of possible device destructions in side converters in order to predict failures by mean of simulation, Th e study of insulated gate bipolar transistor (IGBT) thermal destructio n under short circuit is investigated, An easy experimental method is presented to estimate the temperature decay in the device from the sat uration current response at low gate-to-source voltage during cooling phase, A comparison with other classical experimental methods is given , Three one-dimensional (1-D) thermal models are also studied. The fir st one is a thermal equivalent circuit represented by series of resist ance-capacitance (RC) cells, the second model treats the discretized h eat-diffusion equation (HDE), and the third model is an analytical mod el developed by building an internal approximation (IA) of the heat-di ffusion problem, It is shown that the critical temperature of the devi ce just before destruction is larger than the intrinsic temperature, w hich is the temperature at which the semiconductor becomes intrinsic. The estimated critical temperature is above 1050 It, so it is much hig her than the intrinsic temperature (similar to 550 K). The latter valu e is underestimated when multidimensional phenomena are not taken into account, The study Is completed by results showing the threshold volt age V-th and the saturation current I-sat degradation when the IGBT is submitted to a stress (repetitive short circuit).