Spurious Turn-On inside a Power Module of Paralleled SiC MOSFETs

摘要

Power modules with well-behaved terminal waveforms could still have their dice suffering from spurious turn-on (cross-turn-on and self-turn-on). Compared to self-turn-on, which is mainly induced by the common-source inductance, cross-turn-on deserves more attention because of its common appearance and severity for the modules with Kelvin-source connection, which has been a standard configuration for SiC module manufacturers.rnSPICE model of one commercial module is developed and verified with accuracy higher than the commercial SPICE model. The susceptibility to cross-turn-on and total switching energy for symmetrical module and asymmetrical module tailored from the commercial layouts are investigated by studying the simulated channel current of each MOSFET die and terminal current of the module in the presence of packages’ parasitic impedances. The peak cross-turn-on current of the symmetrical module is 16% of that of the asymmetrical module. Symmetrical layout greatly mitigates cross-turn-on while maintaining similar switching energy under various input voltages, low-side gate resistances, and switching currents.