IGBT Modules - Technologies, Driver and Application (Second Edition) - page 364

Selection of IGBTs with low Miller capacitance C
and substantial gate-
emitter capacitanceC
Optimise the internal layout of the module regarding semiconductor chips in
parallel connection.
Optimise the external connection layout of IGBT modules in parallel
IGBT turn-off
At the end of theMiller plateauduring IGBT turn-off
Oscillation frequency 10…50MHz
Influencing factors
Internal module construction
IGBT characteristic
Low junction temperature
High collector-emitter voltage
Collector current
External interconnection
Tab. 9.2
Influencing factors of possible oscillations during IGBT turn-off
hows a comparison of a module with optimised internal layout and one which
has not beenoptimised.
Fig. 9.4
Impact themodule layout has on the turn-off behaviour of an IGBTmodule
9.4 Tail current oscillations
Under certain circumstances it may come to oscillations in the tail current of IGBTs and
even diodes. Internal processes in the chipwill excite the LC-oscillator –made up of the
semiconductor chip and the initially described parasitic components – to become active.
The excitation is caused by the so-called PETT (Plasma Extraction Transit Time)
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