Admissible And Inadmissible Winding Systems For Parallel Connections Of Converters - Siemens SINAMICS G130 Engineering Manual

Both types of modulation systems, i.e. space vector modulation and pulse-edge modulation, can be used. When the
parallel connection is supplied by Basic Infeeds or Smart Infeeds, the maximum obtainable output voltage is almost
equal to the line supply voltage on the input side of the Infeed (97 %). When the parallel connection is supplied by
Active Infeeds a higher output voltage than the line supply voltage on the input side of the Infeed can be obtained due
to the increased DC link voltage.
The current reduction for parallel connections is 5 % referred to the rated currents of the individual Motor Modules.
Note:
With earlier versions of Motor Modules (firmware < 4.3 in combination with the Control Interface Board CIB instead of
the Control Interface Module CIM), space vector modulation was the only permissible modulation method for motors
with common winding systems. It was not possible to use pulse-edge modulation because the electrical coupling
between the systems prevented a smooth transition between space vector modulation and pulse-edge modulation.
When the parallel connection was supplied by Basic Infeeds or Smart Infeeds, the maximum output voltage was
limited to about 92% of the line supply voltage, because pulse-edge modulation was not available. When the parallel
connection was supplied by Active Infeeds, it was possible to obtain a higher output voltage than the line supply
voltage even without pulse-edge modulation due to the increased DC link voltage.
1.15.7

Admissible and inadmissible winding systems for parallel connections of converters

The previous sections have discussed the subject of motors with electrically isolated winding systems and motors
with a common winding system, but without exactly defining the properties that are required of "electrically isolated
winding systems" or "common winding systems" to make them suitable for operation with parallel connections of
SINAMICS converters.
The possible variants of winding systems for converter parallel connections are discussed in more detail below and
the systems are categorized as either admissible or inadmissible for parallel connections of SINAMICS converters.
The following are admissible:
a) Motors with electrically isolated winding systems in which the individual systems are not electrically
coupled and not out of phase with one another.
b) Motors with a common winding system in which all parallel windings inside the motor are interconnected
in the winding overhang or in the terminal box in such a way that they have the external appearance of one
single winding system.
The following are inadmissible:
c) Motors with electrically isolated winding systems in which the individual systems are out of phase with
one another. This applies to firmware versions up to and including 4.5. With firmware version 4.6 and higher,
motors with a phase displacement of 30° can basically also be operated on parallel connections of
SINAMICS converters when certain boundary conditions are fulfilled. Further information is available on
request.
d) Motors with separate winding systems on the input side which have a common, internal neutral.
Admissible and inadmissible winding systems for parallel connections of converters illustrated by the example of motors
with three parallel windings
Fundamental Principles and System Description
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