Temperature and Switching Rate Dependence of Crosstalk in Si-IGBT and SiC Power Modules

摘要

The temperature and dependence of crosstalk has been analyzed for Si-IGBT and SiC-MOSFET power modules. Due to a smaller Miller capacitance resulting from a smaller die area, the SiC module exhibits smaller shoot-through currents compared with similarly rated Si-IGBT modules in spite of switching with a higher and with a lower threshold voltage. However, due to high voltage overshoots and ringing from the SiC Schottky diode, SiC modules exhibit higher shoot-through energy density and induce voltage oscillations in the dc link. Measurements show that the shoot-through current exhibits a positive temperature coefficient for both technologies, the magnitude of which is higher for the Si-IGBT, i.e., the shoot-through current and energy show better temperature stability in the SiC power module. The effectiveness of common techniques of mitigating shoot-through, including bipolar gate drives, multiple gate resistance switching paths, and external gate–source and snubber capacitors, has been evaluated for both technologies at different temperatures and switching rates. The results show that solutions are less effective for SiC-MOSFETs because of lower threshold voltages and smaller margins for negative gate bias on the SiC-MOSFET gate. Models for evaluating the parasitic voltage have also been developed for diagnostic and predictive purposes. These results are important for converter designers seeking to use SiC technology.