Encoderless Vector Control; Structure Of Vector Control Without Encoder (Sensorless) - Siemens SINAMICS G120XA Operating Instructions Manual

Advanced commissioning
6.6 Motor control
6.6.3

Encoderless vector control

6.6.3.1

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 6-64 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
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
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. I
288
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, 03/2019, FW V1.0, A5E44751205B AB
and
q
SINAMICS G120XA converter