Siemens CU240B-2 - Vector Control with Speed Controller; Overview

Advanced commissioning
6.5 Motor control
Converter with the CU240B-2 and CU240E-2 Control Units
246 Operating Instructions, 01/2016, FW V4.7 SP6, A5E34259001B AC
6.5.2
Vector control with speed controller
6.5.2.1
Overview
Overview
The vector control comprises closed-loop current control and a higher-level closed-loop
speed control.
1)
For induction motors
Image 6-34 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
d
● Current component I
q
● Speed actual value
The setpoint of the current component I
d
(flux setpoint) is obtained from the motor data. For
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
q
(torque setpoint). The closed-loop control responds to a higher
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