SIEMENS
ROBICON Perfect Harmony
Liquid-cooled drives
5/6
Siemens D 16.2 – 2012
5
Function
Output voltage characteristics
Output voltage
Quantity
Value
Distortion at rated voltage
(as a % of rated output voltage)
without over-modulation: ≤ 2 %
(for the first 20 harmonics)
with over-modulation: ≤ 3 %
1)
(for the first 20 harmonics)
Unbalance
(as a % of rated output voltage)
≤ 1 %
dV/dt
2)
< 1000 V/µs for 750 V
Harmonic voltage factor (HVF)
3)
< 0.02
Harmonic voltage factor as a function of ranks with 750 V
cells (WCIII)
Number of cells
Output voltage
kV
HVF
9
4.16
4)
0.019
12
4.80
0.012
15
6.00
0.008
15
6.60
0.007
18
7.20
0.006
18
8.00
0.005
Output current
Quantity
Value
DC component
(as a % of rated output current)
≤ 1 %
Distortion of THD
5) 6)
(as a % of rated output current;
when motor and drive ratings
are equal and the motor leakage
reactance is 16 % or higher)
without over-modulation ≤ 3 %
with over-modulation ≤ 4.5 %
Output voltage characteristics
1)
Only WCIII drives with a specific cell count and rated output voltage will
operate in over-modulation in the 95-100% speed range. Higher output
voltage and current harmonic components at 5th and 7th harmonic
frequencies will exist as reflected in the THD and torque pulsation values.
2)
Although output dV/dt values are high, the control ensures that only one
cell switches at a particular instant. The magnitude of voltage steps \
applied to the motor are thus smaller than the rated voltage (and equal
to the DC-bus voltage of a single cell), which limits the stress on the
insulation of the first few turns (of the motor winding).
3)
No motor derating is required when the inverter voltage waveform
has a HVF value that is less than 0.03. HVF. All Perfect Harmony
configurations (with more than 9 cells) meet this requirement.
4)
The output current distortion limit of 3 % is valid for drives with # of cells
≥ 9 and no over-modulation. As the number of cells increases, the current
distortion decreases to below 2 % for 18 cell drives with a typical motor.
5)
The output current distortion limit of 3 % is valid for drives with number
of cells ≥ 9 and no over-modulation. As the number of cells increases, the
current distortion decreases to below 2 % for 18 cell drives with a
typical motor.
6)
Most motors have a leakage reactance that is greater than 16 %. Output
current distortion is inversely proportional to motor leakage reactance, i.e.
as motor leakage reactance decreases, output current distortion increases.
Engineering Information