Extended Torque Control (Kt Estimator, Servo) - Siemens SINAMICS S120 Function Manual

Function modules

9.6 Extended torque control (kT estimator, servo)

9.6 Extended torque control (kT estimator, servo)
Overview
Function module "Extended torque control" increases the torque accuracy. It comprises the
following modules:
● k
● Compensation of the voltage emulation error of the converter (p1952, p1953, p1954)
● k
Note
When this function module is activated, the maximum number of drives that can be controlled
from a Control Unit is reduced by at least one drive.
Function description
The adaptation of the torque constants for synchronous motors is used to improve the absolute
torque accuracy for the control (closed-loop) of synchronous motors. The magnetization of the
permanent magnets varies as a result of production tolerances and temperature fluctuations
and saturation effects. The function "k
control to the prevailing magnetization. It only makes sense to use the k
conjunction with the friction characteristic as the k
The frictional losses must be compensated from the friction characteristic using a
supplementary torque.
The k
order to achieve a high torque accuracy. Before using the k
identification (p1909, p1910) must be performed. In this procedure, the values for stator
resistance (p0350), leakage inductance (p0356) and voltage emulation errors (p1952, p1953,
p1954) are determined. With p1954 ≠ 0, a change to the DC link voltage and the pulse
frequency for the voltage emulation error are taken into account. The cable resistance must be
entered in p0352 before motor data identification.
The motor should be at room temperature when the identification routine is carried out.
Compensation of the voltage emulation error must be activated (p1780.8 = 1). The motor
temperature (p0600) should be sensed using a KTY or PT1000 sensor (p0601 = 2 or 3).
The k
dependent quantities. The estimate is less accurate if a motor temperature sensor is not
connected.
The k
converter always has small inaccuracies. The lower the output voltage and speed, the more
inaccurate the estimate. This is the reason why the estimation is deactivated below a specific
speed. The estimated value is smoothed using time constant p1795. The correction value for
the torque constant is displayed in r1797.
In the range below p1752, the torque accuracy can be improved using the k
the rotating motor data identification, torque constant kT is identified for various currents and
saved in p0645...p0648 as polynomial. The current dependency of the torque constant can be
442
estimator (only for synchronous motors)
T
characteristic (p0645...p0648) (only for synchronous motors)
T
estimator requires the most accurate values for the motor parameters as possible in
T
estimator requires the motor temperature in order to track/correct the temperature-
T
estimator is only activated above a specific speed (p1752). The terminal voltage of the
T
estimator" adapts the torque constant k
T
estimator corrects the inner motor torque.
T
T
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
[Nm/A] in the
T
estimator in
T
estimator, a motor data
characteristic. For
T
Drive functions