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 High-Voltage IGBT turn-off at transition from overcurrent to desaturation

Authors & Affiliations

Weinan Chen, Chaozheng Qin, Josef Lutz, Thomas Basler
Chemnitz University of Technology
Chemnitz, Germany

DOI

10.14311/ISPS.2021.006

Abstract

 The turn-off capability of a power semiconductor is normally given by the datasheet with test conditions.
The RBSOA (Reverse Bias Safe Operation Area) diagram limits the collector-emitter peak voltage and
maximum turn-off current [1]. As mentioned in the early literature and many datasheets of IGBT power
modules, the current which can be turned off is limited to twice the nominal current, in the between this
and short circuit it is forbidden to turn off the device [2]. In this paper, the turn-off behaviour of HVIGBTs at the transition from overcurrent to desaturation is investigated with a 2D half-cell model in
Synopsys TCAD as well as with single chip measurements. This article focuses on the classification of the
turn-off process near the V
CE desaturation, with respect to the plasma- and electric field distribution,
dynamic avalanche, as well as electric field peaks which occur during this process. It shows that the IGBT
can be operated in this former forbidden region successfully, and a beginning desaturation releases
dynamic avalanche.

Keywords:

 Overcurrent, IGBT turn-off behaviour, RBSOA, desaturation, dynamic avalanche, TCAD.

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