Calibration and Measurement of Vce-Tj Correlation With Temperature Distribution of IGBT and Interconnections

Online junction temperature (T_j) estimation for power semiconductor device insulated gate bipolar transistor is of great importance for reliability assessment and enhancement. Typically, T_j can be online calculated using the pre-calibrated correlation with on-state collector-emitter voltages (V_ce) at loading current. However, the uneven temperature distribution inside the device during calibration is different from the conditions during operation. Uneven thermal distribution inside the device and self-heating of chips will cause significant estimation error by using the pre-calibrated T_j - V_ce correlation, as the voltage drop on interconnections will be different. In this article, a novel calibration method of T_j - V_ce relationship under pulsewdith modulation operation of device is proposed. By varying the switching frequency with fixed heatsink temperature, adjustable self-heating conditions and temperature distributions inside the device can be recreated. Moreover, a group of new relationships between junction temperature, heatsink temperature and temperature of interconnections inside device are revealed. By using the discovered relationship, the influence of uneven temperature distribution on V_ce can be compensated in a noninvasive way, which can achieve higher accuracy in T_j estimation compared to the conventional method.