IGBT Modules - Technologies, Driver and Application (Second Edition) - page 388

Fig. 11.6
Pre-charge circuit
High peak currents can occur not only at the time of connection to themains. Also with
a brief drop in voltage and after the recovery of the nominal voltage, peak currents
occur. These represent a strain for the semiconductors in dependence of the voltage
drop. The pre-charge circuit should be "intelligently designed" and, for such incidents,
include for example an under-voltagemonitor. Otherwise, these re-charge currents, so-
called surge currents, have to be limited bymains or DC-bus chokes. A brief mains drop
with subsequent surge current can lead to the failure of power electronic components
. In PIM or CIBmodules the connection to the rectifier diode on the front side
is donewith bondwires. Themetallisation (usually aluminium) of the chip front sidemay
be damagedwith the surge current strain. High current densities in the bond feet let the
aluminiummelt, whichafterwards leads tobondwire lift-off.
1...,378,379,380,381,382,383,384,385,386,387 389,390,391,392,393,394,395,396,397,398,...548
Powered by FlippingBook