Siemens SINAMICS S120 Function Manual page 529

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 9-27
Owing to the electrical isolation of the winding systems, this arrangement offers the following
advantages:
● No decoupling measures (minimum cable lengths and no motor reactors) are required at the
Motor Module output in order to limit any potential circulating currents between the Motor
Modules connected in parallel.
● Both types of modulation system, i.e. space vector modulation and pulse-edge 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 infeed units (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.
In reference to the rated values for individual Motor Modules, the derating factor is 5%.
Drive functions
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
Parallel connection of two Motor Modules to one motor with double winding system
Function modules
9.10 Parallel connection of power units
527