Siemens SINAMICS G130 Engineering Manual page 41

RSC >> 50
Typical line currents of a 6-pulse rectifier with line reactor u
2. SINAMICS S120 Smart Infeed in regenerative operation
The SINAMICS S120 Smart Infeed is a rectifier / regenerative unit for four-quadrant operation and is equipped with
IGBT modules. On the line side a line reactor with a relative short-circuit voltage of 4 % is necessary. More detailed
information on the Smart Infeed can be found in the section "SINAMICS Infeeds and their properties" in the
subsection "Smart Infeed". The following pages only deal with the harmonic effects of the Smart Infeed.
The rectifier bridge for rectifier operation (motor operation) consists of the diodes integrated into the IGBT modules so
that a 6-pulse diode bridge circuit is present in motor operation. All the information given in preceeding pages apply
here.
The bridge circuit for regenerative operation consists of the IGBTs which are connected anti-parallel to the diodes. So
this is also a 6-pulse bridge circuit, but the line currents in regenerative operation are slightly different from those in
motor operation and show slightly different harmonics.
Smart Line Module with diodes for motor operation and IGBTs for regenerative operation
In both, motor and regenerative operation, only odd harmonic currents and harmonic voltages that cannot be divided
by 3 occur, with the following harmonic order numbers h:
h = n 6 ± 1
*
i.e.
h = 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, ...
The following table shows the typical current harmonics in motor and regenerative operation with a reactor on the line
side (relative short-circuit voltage of the line reactor = 4 %)
For this a supply system constellation with an average supply inductance and an average relative short-circuit power
of RSC = 50 has been taken as a basis for the calculations.
Current harmonics in rectifier operation (motor operation)
h 1 5
I 100 % 30.6 %
h
Current harmonics in regenerative operation
h 1 5
I 100 % 20 %
h
Typical current harmonic values for the SINAMICS Smart Infeed in rectifier (motor) operation and regenerative operation
with a line reactor of 4 %
Fundamental Principles and System Description
RSC = 50
with n = 1, 2, 3, ...
7 11
8.6 % 5.7 %
7 11
16 % 11 %
= 2% as a function of the relative short-circuit power RSC
k
13 17 19
3.1 % 2.1 % 1.6 %
13 17 19
8 % 7 % 6 %
SINAMICS Engineering Manual - May 2008
Engineering Information
RSC < 15
23 25
1.2 % 1.1 %
23 25
5 % 4 %
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© Siemens AG
THD(I)
32.6 %
THD(I)
32 %