Siemens SINAMICS G120C DP

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.
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1)
for induction motors
2)
Settings that are required
Figure8-52 Simpli󹪝ed 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
q
• Current component I
q
• Speed actual value
The setpoint of the current component I
d
(󹪞ux setpoint) is obtained from the motor data.
For speeds above the rated speed, the converter reduces the 󹪞ux setpoint along the 󹪝eld
weakening characteristic.
When the speed setpoint is increased, the speed controller responds with a higher setpoint
for current component I
q
(torque setpoint). The closed-loop control responds to a higher
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.
Advanced commissioning
8.20Motor control
SINAMICS G120C Converters
310 Operating Instructions, 02/2023, FW V4.7 SP14, A5E34263257B AK