SIEMENS
ROBICON Perfect Harmony
Liquid-cooled drives
2
2/4
Siemens D 16.2 – 2012
Design
Drive topology
The ROBICON Perfect Harmony drives achieve an
uncompromising performance by employing proven
technology in a modular configuration, as shown in Figure
2.2. Medium-voltage levels are obtained by combining the
outputs of multiple low-voltage power cells. The low-voltage
power cells are simplified variations of standard 2 level PWM
motor drives for low voltage service, which have been built in
high volume for many years.
Figure 2.2 Topology of ROBICON Perfect Harmony drives (3 cells)
For higher output voltage capabilities, the ROBICON Perfect
Harmony topology can be extended to have up to 8 power
cells
1)
in series in each phase, with additional secondary
windings (number of secondaries equals number of power
cells) on the integral isolation transformer.
Each power cell is capable of receiving input power at 750
V AC, 3-phase, 50/60 Hz and delivering that power to a
single phase load at a variable frequency from 0.5 to the
maximum rated output frequency of the drive.
Transformer
The transformer is an integral part of the drive and cannot
be specified or obtained separately. It has been carefully
designed over several generations to function properly with
the ROBICON Perfect Harmony drive.
ROBICON Perfect Harmony transformers are dry-type
liquid-cooled. They are designed specifically for use with
a particular ROBICON Perfect Harmony drive and have 9
to 18 extended delta secondaries. The secondary currents
are rich in harmonics, but the primary current is virtually
sinusoidal. It is very important to recognize that this is
no ordinary transformer which can be obtained as an
off-the-shelf item.
The usual standards, ANSI C5712.51 and C5712.91, apply
to transformers with only a few windings and which are
subjected to sinusoidal currents. Thus, there are some
important exceptions and modifications to the application
of these standards to ROBICON Perfect Harmony transformers.
Proven IGBTs
Insulated Gate Bipolar Transistors (IGBTs) form the backbone
of the ROBICON Perfect Harmony drive. Built in high volumes
and serving as a proven power device across the industrial
power control industry, IGBT technology has been in existence
for more than a decade. The stability and availability of IGBTs
give reliable, long-term, lifecycle confidence.
Linked low-voltage cells
In the ROBICON Perfect Harmony, a series of low-voltage
cells (see figure 2.3) are linked together to build the medium-
voltage power output of the drive system. This patented
modular configuration gives the ROBICON Perfect Harmony
many advantages when it comes to maintenance, power
quality and reliability. It also provides the basis for one of its
most important advantages – increased availability through
the advanced cell bypass option.
Figure 2.3 Schematic of a typical power cell.
Special
transformer
with 9 isolated
secondaries
Input power
3-phase AC
Power
cell
B1
Power
cell
C1
Power
cell
A1
Power
cell
B2
Power
cell
C2
Power
cell
A2
Power
cell
B3
Power
cell
C3
Motor
Power
cell
A3
G_D015_EN_00009
T2
T1
1
2
3
Q1
Q3
Q2
Q4
+
+
Power
output
of cell
Dedicated
winding on
power
transformer
Fiber optic
signals
to and from
master control
G_D015_EN_00010
Local control circuits
Local
control
power
IGBTs Q1-Q4
Introduction
1)
WCIII is limited to 6 power cells in series.