Siemens SINAMICS G120 Operating Instructions Manual page 123

Selecting the suitable control mode
Control mode
Motors that can be
operated
Power Modules
that can be oper-
ated
Application exam-
•
ples
Closed-loop con-
•
trol characteristics
•
•
•
Max. output fre-
quency
Torque control
Commissioning
•
Converter with CU230P-2 Control Units
Operating Instructions, 04/2015, FW V4.7 SP3, A5E34257946B AB
U/f control or flux current control (FCC)
Induction motors
Pumps, fans, and compressors with flow
characteristic
Typical correction time after a speed change:
100 ms ... 200 ms
Typical cor-
rection time
after a load
surge: 500 ms
The control
mode is suit-
able to ad-
dress the
following re-
quirements:
– Motor power ratings < 45 kW
– Ramp-up time 0 → Rated speed (de-
pendent on the rated motor power):
1 s (0.1 kW) ... 10 s (45 kW)
– Applications with increasing load torque
without load surges
The control mode is insensitive with respect
to inaccurate motor data settings
550 Hz
Without torque control
Contrary to vector control, no speed control-
ler has to be set
5.3 Commissioning using a BOP-2 operator panel
Induction, synchronous and reluctance motors
No restrictions
Pumps and compressors with displacement
•
machines
Typical correction time after a speed change:
•
< 100 ms
Typical correction
•
time after a load
surge: 200 ms
The vector control
•
controls and limits
the motor torque
Torque accuracy
•
that can be
achieved: ± 5 %
for 15 % ... 100 %
of the rated speed
We recommend vector control for the following
•
applications:
– Motor power ratings > 11 kW
– For load surges 10 % ... >100 % of the rat-
ed motor torque
The vector control is necessary for a ramp-up
•
time 0 → Rated speed (dependent on the rated
motor power):
< 1 s (0.1 kW) ... < 10 s (250 kW).
Torque control with higher-level speed control
Commissioning
Vector control
240 Hz
123