SIEMENS
SINAMICS DCM
Engineering information
12-pulse operation
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Siemens D 23.1 · 2014
5
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Overview
SINAMICS DC MASTER for 12-pulse operation
For 12-pulse operation, two SINAMICS DC MASTER converters
are supplied with voltages displaced by 30 degrees. This con-
figuration reduces the harmonics. Each SINAMICS DC MASTER
conducts half of the total current. One of the SINAMICS DC
MASTER units is operated with closed-loop speed control, and
the second with closed-loop current control. A peer-to-peer con-
nection is used to transfer the current setpoint from the first to the
second SINAMICS DC MASTER.
Smoothing reactors are required in the DC circuit for 12-pulse
operation.
Calculating the smoothing reactor
•
A smoothing reactor is used for each of the two partial con-
verters. The reactor comprises a 2-value reactor; this means
that the inductance of the reactor is defined for two current
values.
•
The reactor is thermally dimensioned according to the rms
value of the DC reactor current.
Calculating the required inductance
1. Inductance of the reactor at 0.2
×
I
dN
(
L
D1
)
2. Inductance of the reactor for
I
dmax
(
L
D2
)
- for 50 Hz line frequency
L
D1
= 0.296
×
10
-3
×
V
di
/(0.2
×
I
dN
)
L
D2
= 0.296
×
10
-3
×
V
di
/(0.33
×
I
dmax
)
- for 60 Hz line frequency
L
D1
= 0.24
×
10
-3
×
V
di
/(0.2
×
I
dN
)
L
D2
= 0.24
×
10
-3
×
V
di
/(0.33
×
I
dmax
)
L
Inductance in H
I
dN
half the rated DC current of the DC motor
I
dmax
half the maximum current of the DC motor
V
di
= 1.35
×
V
N
V
N
rated line supply voltage
12-pulse operation
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More information
For further information and application documents, please
go to the following website address:
siemens.com/WW/view/en/38157755/130000
(Entry type "Application")
■
Overview
SINAMICS DC MASTER to supply high inductances
To supply high inductances – such as the fields of large DC
or synchronous motors or lifting solenoids – the gating unit is
changed over to long pulses using the appropriate parameter
settings. At high levels of inductance, the long pulses ensure
that the thyristors are reliably triggered. In this case, the arma-
ture circuit of the units is not used to supply the armature of DC
motors, but to supply large field windings.
Note:
An external overvoltage protective circuit must be provided
at the DC voltage output of the SINAMICS DC MASTER (e.g.
SICROWBAR DC overvoltage protection).
■
More information
For further information and application documents, please
go to the following website address:
siemens.com/WW/view/en/38157755/130000
(Entry type "Application")
■
Overview
Protection against condensation
SINAMICS DC MASTER units are designed in compliance with
climate class 3K3 (EN 60721-3-3) without condensation.
When supplied to tropical countries, we recommend that the
electrical cabinets are equipped with cabinet heating elements.
Units with coated PCBs are optionally available (option M08);
these are insensitive to unfavorable environmental conditions. In
order to guarantee safe and reliable operation, under all circum-
stances, it should be avoided that the units are commissioned
with PC boards with moisture condensation.
G_D023_EN_00010a
Converter transformer
e.g. Dy5Dd0 or Yy0Yd11
Overvoltage protection
Overvoltage protection
Smoothing
reactor
Smoothing
reactor
Supply of high inductances
Protection against condensation
© Siemens AG 2014