Die Level Thermal Analysis in SiC Power Module for Traction Inverter

This paper presents a compact and cost-effective DC/AC converter solution to test the thermal imbalance of dice placed in parallel in a silicon carbide power module. The analysis is performed in continuous operating mode, by detecting the temperatures directly on each die with an infrared thermal camera. The system validation has been carried out by analysing two traction inverter modules. Each module has been assembled with dice selected according to their gate-source voltage threshold; the final goal being the extraction of a mathematical model, matching experimental data, to be able to predict the thermal imbalance. Input to the model is the Vth selection criteria when the inverter is used in the range of voltage and power typical of the electric vehicle applications. Furthermore, it has been necessary to increase the test time to analyse the dice behaviour when subjected to the current profile typical of the electric cars’ lifecycle. The results highlight that the appropriate selection of the dice inside the module, based on the threshold voltage, improves thermal performance, reducing the imbalance.