IGBT Modules - Technologies, Driver and Application (Second Edition) - page 344

Fig. 8.6
Dynamic current distribution of threemodules with and without optimised stray
inductance in the commutationpath
For the practical verification of a proper setup of the application the double pulse test
may be used as described in chapter
By this test the basic behaviour of the static
and dynamic response in a parallel connection can be investigated. However, the
followingpoints have tobe considered:
The double pulse test is not able to apply sufficient power losses in the devices
under test to establish a load generated heat-up. That means the thermal
effect of the positive temperature coefficient of the IGBT will not be taken into
account. Accordingly, a system which shows an imbalance of the current
distribution in the double pulse test will show a better balancing during real
To get correct results it is recommended to perform the double pulse test not
with a standard half-bridge but with an H-bridge topology. Otherwise, the
observed current flow paths will not be identical with the current flow paths in
the final application. In the real application the load inductor is not directly
connected to the DC-bus, but always to at least to switches while the load
current is flowing.
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