Encoderless Vector Control; Structure Of Vector Control Without Encoder (Sensorless) - Siemens SINAMICS G120C USS/MB Operating Instructions Manual

Advanced commissioning
6.19 Motor control
6.19.3

Encoderless vector control

6.19.3.1

Structure of vector control without encoder (sensorless)

Overview
The vector control comprises closed-loop current control and a higher-level closed-loop speed
control.
for induction motors
1)
Settings that are required
2)
Figure 6-51 Simplified function diagram for sensorless vector control with speed controller
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 current component I
setpoint by adding a higher slip frequency to the output frequency. The higher output frequency
268
q
q
(flux setpoint) is obtained from the motor data. For
d
(torque setpoint). The closed-loop control responds to a higher torque
q
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34263257B AF
SINAMICS G120C converter