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

Advanced commissioning
8.20 Motor control
8.20.3

Sensorless vector control

8.20.3.1

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 8-52 Simplified function diagram for sensorless vector control with speed controller
Using the motor model, the converter 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
For speeds above the rated speed, the converter 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
torque setpoint by adding a higher slip frequency to the output frequency. The higher output
frequency also results in a higher motor slip, which is proportional to the accelerating torque.
310
q
q
(flux setpoint) is obtained from the motor data.
d
(torque setpoint). The closed-loop control responds to a higher
q
Operating Instructions, 02/2023, FW V4.7 SP14, A5E34263257B AK
SINAMICS G120C Converters