Experimental Evaluation of IGBT Junction Temperature Measurement via a Modified-VCE (ΔVCE_ΔVGE) Method with Series Resistance Removal

Abstract:
Temperature sensitive electrical parameters (TSEPs) allow junction temperature measurements on power semiconductors without modification to module packaging. The on-state collector-emitter voltage (VCE) in IGBTs is an attractive option for junction temperature measurement since it is relatively easy to measure during operation. Nevertheless, the resistive contribution of interconnection and packaging materials has been shown to introduce large errors when using the VCE for junction temperature measurement. This paper uses an IR camera to experimentally evaluate a modified-VCE method designed to remove this series resistance contribution. This method can be described as the difference in VCE at two different gate voltages (15 V and 13 V). Experimental validation focuses primarily on the accuracy of the temperature measurement and investigates paralleled chip configurations as well as multiple devices with differing geometry and manufacturer. The modified-VCE shows significant improvement over the normal-VCE in terms of correlation to mean junction temperature, with maximum errors typically below 10 ºC. These results are additionally compared with one traditional and robust TSEP: the voltage drop under low current injection.