n Gate to source capacitor in gate drive?
This is sometimes added if a specific instance is susceptible to dv/dt turn-on (layout, lower current drive, installation). A collector-gate current, via the parasitic capacitance: Ccg flows at every switching event. If the gatedrive does not have enough drive capability to absorb this charge then the IGBT can inadvertently turn on. 

By adding a capacitor in parallel with the devices Cge, this capacitor will aid in absorbing the charge at the expense of increasing the gatedrive power need