SIEMENS
ROBICON Perfect Harmony
Liquid-cooled drives
5
5/7
Siemens D 16.2 – 2012
Function (continued)
With all cells operating
The maximum output voltage of the drive in terms of the
number of ranks and the secondary-side cell voltage is
given as:
N = number of ranks (Number of Cells / 3)
V
cell_rating
= 750 V
V
input
= actual input line voltage
V
input
_rated = rated drive input voltage
Tap_Setting = 1.00 (for 0 % tap), 0.95 (for +5 % tap) or 1.05
(for –5 % tap)
Output voltage capability must be calculated based on worst-
case line voltage (minimum value).
With over-modulation (for 750 V cells only)
When over-modulation is used in the control for additional
voltage capability, the maximum output voltage increases by
5 % and is given as:
Note
The use of over-modulation is discouraged. However, in
exceptional cases over-modulation may be utilized but only
after consulting the factory or your local Siemens
sales representative.
Available drive power as a function of input voltage
Input under-voltage rollback
In the event that the input voltage falls below 90 %, the
attached description provides details of drive limitations.
When the input line voltage drops below 90 % of its rated
value, the drive limits the amount of power (and hence the
torque) that can be delivered to the load. The maximum
allowable drive power as a function of line voltage is shown
in the figure below. At 66 % input voltage, the maximum
drive power is limited to 50 % and is quickly reduced to a
slightly negative value (regen limit) at 65 %. This limit
forces the drive to absorb power from the motor and
maintain the (power cell) DC-bus voltages in case the
input voltage recovers during MV ride-through. The limit is
implemented as an inverse function of speed in order to
maintain constant power flow to the (cell) DC-bus.
Figure 5.1 Drive power (P
max
) as a function of input voltage
magnitude (E
rms
)
Once the input voltage falls below 65 %, the drive reduces
output power to a slightly negative value and maintains
synchronism with the motor for a period greater than five
cycles. Once input voltage is restored, the drive begins by
magnetizing the motor and then continues with torque
production. There is no delay in drive restart.
If input voltage is not restored after five cycles the drive
maintains synchronism with the motor as long as the power
cells can operate without input power or as long as there is
motor voltage (to synchronize to). Once operation of any
power cell stops or if motor voltage decays significantly, the
drive trips on a loss of input medium-voltage.
Engineering Information
%
%
105
100
50
65
66
90
0
P
max
E
rms max
Regen limit
G_D015_EN_00012
Drive Power (P
max
) vs Input Voltage Magnitude (E
rms
)