IGBT Modules - Technologies, Driver and Application (Second Edition) - page 422

Themains side (or line side) converter operates with a fundamental frequency of either
50Hz or 60Hz, depending on the country. The machine side converter, on the other
hand, has to cover a range of 0Hz to about 20Hz. Assuming an equal load of both
converters, thenmuch larger oscillations
of the junction temperaturewill result in the
machine-side converter, as the simulation i
shows. Thismeans an increase
in stress with respect to the reliability (specifically, the load-cycle capability) of the
modules comparedwith the requirements of themodules in the line-side converter. The
operating point with the greatest stress for themodules is the fundamental frequency of
0Hz, where the largest temperature change occurs. It should be noted that this
operating point can occur in a wind power plant for an indefinite period and therefore
has to be consideredwhen selecting the IGBTmodules.
Fig. 11.46
Dependence of the junction temperature on the fundamental frequency of the
11.6.5Traction inverter
For historical reasons, different power supply systems for railway traction applications
have been established around the world. In addition to the AC-systems there is also a
DC-system. With the use of converters, the development and cross-border movement
simplified, since regardless of the grid, uniform drive systems (based on the design
concept) are used. The drivemotor is predominantly an inductionmachine. InAC power
supplies, the voltage is reduced by a transformer to a level suitable for the power
electronics input stage. In DC-systems, however, the converter is directly connected to
the grid.
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