Function modules
8.6 Extended torque control (kT estimator, servo)
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
485
Extended torque control (kT estimator, servo)
The "Extended torque control" function module comprises two modules - the k
T
estimator
and the compensation of the voltage emulation error of the drive converter. As a
consequence, the torque accuracy is increased.
Note
When this function module is activated, the maximum number of drives that can be
controlled from a Control Unit is reduce
d by at least one drive.
● k
T
estimator (only for synchronous motors)
● Compensation of the voltage emulation error of the drive converter (p1952, p1953)
● Configuration via p1780
The extended torque control is activated offline:
1. Click the drive and right-click to open the shortcut menu "Properties ... ".
The "Object Properties" window opens.
2. Click the "Function modules" tab.
The selection of possible function modules opens.
3. Click the "Extended torque control" checkbox to activate this option.
4. Click "OK" to activate the function module.
5. Select the "Connect to selected target devices" option.
6. Call the "Download project to target system" function.
Alternatively, you can also activate function modules in STARTER under "Configuration >
Function modules / technology packages".
Activation can be checked in parameter r0108.1.
Description of the k
T
estimator
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
T
estimator" adapts the torque
constant k
T
[Nm/A] in the control to the prevailing magnetization. It only makes sense to use
the k
T
estimator in conjunction with the friction characteristic as the k
T
estimator corrects the
inner motor torque. The frictional losses must be compensated from the friction characteristic
using a supplementary torque.