Siemens Sinamics S120 Function Manual page 413

Parallel connection of two Motor Modules to one motor with double winding system
Motors in the power range from about 1 MW to 4 MW, for which power units connected in
parallel are generally used, frequently have several parallel windings. If these parallel
windings are separately routed to the terminal box of the motor, a motor is obtained with
winding systems that can be separately accessed. In this case, you can dimension a parallel
Motor Module connection so that each motor winding system is precisely supplied from one
of the Motor Modules connected in parallel. The diagram below shows this type of
arrangement.
Figure 7-27
Owing to the electrical isolation of the winding systems, this arrangement offers the following
advantages:
● Decoupling measures are not required at the infeed output in order to limit any potential
● Both types of modulation system, i.e. space vector modulation and pulse-edge
For a parallel connection, the current reduction referred to the rated value for the individual
Motor Modules is 5 %.
Drive functions
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
Example 1: parallel connection
circulating currents between the parallel-connected Motor Modules (no minimum cable
lengths and no motor reactors).
modulation can be used, i.e. when the parallel connection is supplied by Basic Line
Modules or Smart Line Modules, the maximum obtainable output voltage is almost equal
to the three-phase AC line voltage connected to the infeeds (97 %). When the parallel
connection is supplied by Active Line Modules, a higher output voltage than the input
voltage at the three-phase end can be obtained due to the increased DC link voltage.
Function modules
7.11 Parallel connection of power units
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