Can application of a reverse-bias voltage (-V_GE) on a gate-to-emitter be exempted in a case where only an FWD is used without an opposite IGBT, such as in a chopper circuit?

Please apply a reverse-bias voltage (-V_GE) of -5 V or higher (-15 V recommended; max. -20 V) between the gate and emitter in the IGBT that is not being used. An insufficient reverse-bias voltage (-V_GE) may cause the IGBT to misfire due to dV/dt at the time of reverse-recovery of the FWD, resulting in damage.
For details, refer to Application Manual Chapter 3-10.