Consider driving the IGBT gate at a voltage equal to the VGE value shown in the datasheet as a test condition for the VCE(sat) and switching characteristics or at a voltage close to VGE (see the following tables). Increasing the gate-emitter voltage (VGE) reduces a margin with respect to the absolute maximum rating whereas reducing the gate-emitter voltage causes VCE(sat) to increase as shown below, increasing conduction loss. If the gate-emitter voltage is too low, a system might not operate satisfactorily because the IGBT is not driven sufficiently. Generally, we recommend a VGE level equal or close to 15 V except for special-purpose IGBTs such as those for strobe light applications.
Also, when there is a difference between the gate bias power supply voltage and the gate-emitter voltage of the IGBT, a design should be created such that the gate-emitter voltage of the IGBT becomes the above-mentioned value.
(Note: Generally, the gate-emitter voltage of an IGBT is set to zero when it is off. In some cases, however, the gate-emitter voltage is reverse-biased to stabilize the IGBT switching operation.)