taiko,
It serves the same function as a power MOSFet driver. When used in switching applications, you want the gate voltage to change state as quickly as possible. In order to do this you must charge up the gate capacitance as quickly as possible. The gate voltage dv/dt = I/C. This means foar a large dv/dt, you must supply a large current to the gate during the time the gate voltage is changing state. This is what the IGBT driver does. It is designed to provide high levels of gate current for short periods of tie.
Regards,
Kral