Operating instructions

Setpoint channel and closed-loop control
7.4 Vector speed/torque control with/without encoder
Drive converter cabinet units
Operating Instructions, 10/2008, A5E00288214A
275
7.4.2 Vector control with encoder
Description
Benefits of vector control with an encoder:
● The speed can be controlled right down to 0 Hz (standstill)
● Stable control response throughout the entire speed range
● Allows a defined and/or variable torque for speeds below approx. 10 % of the rated motor
speed to be maintained
● Compared with speed control without an encoder, the dynamic response of drives with an
encoder is significantly better because the speed is measured directly and integrated in
the model created for the current components.
Motor model change
A model change takes place between the current model and the observer model within the
speed range p1752 x (100 % - p1756) 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% to
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 supplementary 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.
Function diagram
FP 4715 Actual speed value and rotor position measurement, motor encoder
FD 6030 Speed setpoint, droop
FP 6040 Speed controller
FP 6050 Kp_n-/Tn_n adaptation
FP 6060 Torque setpoint
FP 6490 Speed control configuration