Vector Control With Speed Controller - Siemens SINAMICS G120C Operating Instructions Manual

6.5.2

Vector control with speed controller

Overview
The vector control comprises closed-loop current control and a higher-level closed-loop
speed control.
For induction motors
1)
Figure 6-33 Simplified function diagram for sensorless vector control with speed controller
All of the function block diagrams 6020 ff. for vector control are provided in the List Manual:
Using the motor model, the inverter calculates the following closed-loop control signals from
the measured phase currents and the output voltage:
● Current component I
● Current component I
● Speed actual value
The setpoint of the current component I
speeds above the rated speed, the inverter reduces the flux setpoint along the field
weakening characteristic.
When the speed setpoint is increased, the speed controller responds with a higher setpoint
for the current component I
torque setpoint by adding a higher slip frequency to the output frequency. Also in the motor,
the higher output frequency results in a higher slip, which is proportional to the accelerating
torque. I
the matching current component I
SINAMICS G120C converter
Operating Instructions, 07/2015, FW V4.7 SP3, A5E34263257B AC
d
q
(torque setpoint). The closed-loop control responds to a higher
q
and I controllers keep the motor flux constant using the output voltage, and adjust
q d
(flux setpoint) is obtained from the motor data. For
d
in the motor.
q
Advanced commissioning
6.5 Motor control
201