Turn-off time measures the interval from the moment a control signal commands a device to stop conducting until the forward current drops to zero and the device recovers its full reverse blocking capability. In power electronics, this includes storage time to sweep out minority carriers and the fall time of the current. Minimizing this duration reduces switching losses and allows power converters to operate at higher switching frequencies.
The switching losses are too high because the IGBT turn-off time is dragging out past 200 nanoseconds.
Driving the gate slightly negative during turn-off can sweep out charge carriers faster and drastically reduce the turn-off time.
Related terms
Fall time
The duration required for a digital signal to transition from a high state to a low state.
Storage time
The delay before a saturated transistor begins to turn off after the base drive is removed.
Turn-on time
The interval required for a semiconductor switch to transition from a blocking state to full conduction.
IGBT
A power semiconductor device that combines a simple gate drive with high-current capability.