The ruggedness of the insulated gate bipolar transistor (IGBT) is one of its important attributes from the application stand point. Models for the forward-, reverse-, and short circuit safe operating area are provided in this chapter. Latchup of the parasitic thyristor in the IGBT can lead to destructive failure. Cell design for suppressing the latchup of the parasitic thyristor in the IGBT is described including adding a deep P-region, reducing the gate oxide thickness, adding a diverter region, and improving the polysilicon gate layout topology. The performance of silicon carbide devices is contrasted with that of silicon devices.