IGBT Modules - Technologies, Driver and Application (Second Edition) - page 160

temperature. In contrast to the Planar NPT IGBT there is no facility to increase this by
reducing the external gate resistor. Under nominal conditions the turn-off behaviour
overall is therefore softer for the Trench IGBT and shows a lesser switching voltage
overshoot than thePlanar NPT IGBT.
3.6 Short circuit behaviour
As mentioned before, the IGBT short circuit behaviour SC1 and SC2 is also analysed
with the half-bridge configuration detailed i
SC1 is a short circuit which already
exists when the IGBT is turned on to it. For this the inductor L is exchanged for a low
inductance shorting bridge. For an SC2 the short circuit happens while the IGBT is
already turnedon.
Fig. 3.31
Short circuitsSC1 andSC2
Manufacturers only specify SC1 short circuits even if this is not explicitly mentioned in
the datasheets or application notes. For an SC2, however, there is no specification.
Problems with applications in which a short circuit SC2 may potentially occur are
discussed in chapter
At this point the basic aspects in the IGBT short
circuit behaviour for cases of SC1 andSC2are contemplated.
Since it may be dangerous to demonstrate a short circuit SC2 it is commonly simulated
by the following procedure: The inductor L in the half-bridge test circuit according t
s reduced to only a few nH. Correspondingly, the current rises during the turned on
phase of the IGBT with a positive
and the inductor takes up the voltage. As soon
as the short circuit current is reached the IGBT starts to desaturate. The rise of the
current is limited, i.e.
. Therefore the inductor can no longer take up voltage
and the IGBT goes from saturated operation over to short circuit operation. The value of
the inductor is chosen such that the IGBT goes into desaturation no earlier than after
hows measurements for the two cases of short circuits. For an SC1 the
pulse duration t
ismeasuredbetween the10%marks of the short circuit current I
. For
anSC2, however, t
is the time between themarks 20%U
and 10% I
The short circuit behaviour of an IGBT is determined by the following factors:
1...,150,151,152,153,154,155,156,157,158,159 161,162,163,164,165,166,167,168,169,170,...548
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