IGBT Modules - Technologies, Driver and Application (Second Edition) - page 151

Technologies IGBTs (status 2009) as an example. Each vertical line in the diagram
represents the corresponding voltage class U
. Each dot represents a particular
technology. It can easily be seen that with rising voltage classes the saturation voltage
increases. Within one voltage class the U
values of the latest technologies are in a
low region, values in theupper range represent the older IGBTgenerations.
Fig. 3.22
Overview of the typical saturation voltages U
at T
= 125°C depending on
the voltage classU
and the technology employed
Further the following parameters are necessary in order to solve
parameters can be takendirectly from the application:
Peak forward current
Modulation factorm
Power factor cos
For ease of calculation various manufacturers offer assistance with online and offline
calculation and simulation software. An example of this has already been detailed i
3.4.1 Forward characteristics at low temperatures
As was detailed in the previous chapter the saturation voltage depends on the IGBT
junction temperature. Values and diagrams regarding this are depicted in the
datasheets. However, specifications regarding temperatures below 25°C are often
As can be seen from Fig. 3.23 below 20°C it may well come to an inversion of the
previous PTC (positive temperature coefficient) behaviour for certain IGBTs based on
NPT and FS technologies. Thismeans that the IGBT shows NTC (negative temperature
coefficient) behaviour from here on. These IGBTs have a low efficiency back side
emitter, i.e. the p-doped collector. Due to the low doping concentration and hence the
low surface doping concentration the contact resistance between the p-layer and the
backside metallisation plays an ever increasing role at low temperatures. With
temperatures below approximately 20°C this influence begins to dominate and the
saturation voltage starts to showNTC behaviour.
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