Vector Control With Encoder - Siemens Sinamics S120 Function Manual

Vector control

4.2 Vector control with encoder

4.2 Vector control with encoder
Benefits of vector control with an encoder:
● The speed can be controlled right down to 0 Hz (standstill)
● Constant torque in the rated speed range
● Compared with speed control without an encoder, the dynamic response of drives with an
● Higher speed accuracy
Motor model change
A model change takes place between the current model and the observer model within the
speed range p1752*(100 %-p1753) and p1752. In the current model range (i.e at lower
speeds), torque accuracy depends on whether thermal tracking of the rotor resistance is
carried out correctly. In the observer-model range and at speeds of less than approx. 20% of
the rated speed, torque accuracy depends primarily on whether thermal tracking of the stator
resistance is carried out correctly. If the resistance of the supply cable is greater than 20 ...
30 % of the total resistance, this should be entered in p0352 before motor data identification
is carried out (p1900/p1910).
To deactivate thermal adaptation, set p0620 = 0. This may be necessary if adaptation cannot
function accurately enough due to the following general conditions. For example, if a KTY
sensor is not used for temperature detection and the ambient temperatures fluctuate
significantly or the overtemperatures of the motor (p0626 ... p0628) deviate significantly from
the default settings due to the design of the motor.
4.3 Speed controller
Both closed-loop control procedures with and without an encoder (VC, SLVC) have the same
speed controller structure, which contains the following components:
● PI controller
● Speed controller pre-control
● Droop
The total of the output variables result in the torque setpoint, which is reduced to the
permissible magnitude by means of the torque setpoint limitation.
150
encoder is significantly better because the speed is measured directly and integrated in
the model created for the current components.
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
Drive functions