Torque Control - Siemens SINAMICS S120 Function Manual

Vector control

5.8 Torque control

5.8 Torque control
With sensorless speed control SLVC (p1300 = 20) or speed control with sensor VC (p1300 =
21), a changeover can be made to torque control (slave drive) via BICO parameter p1501. A
changeover cannot be made between speed and torque control if torque control is selected
directly with p1300 = 22 or 23. The torque setpoint and/or supplementary setpoint can be
entered using BICO parameter p1503 (CI: torque setpoint) or p1511 (CI: supplementary
torque setpoint). The supplementary torque is active both with torque and speed control.
This particular feature with the supplementary torque setpoint allows a precontrol torque to
be applied for speed control.
Note
For safety reasons, connecting to fixed torque setpoints is currently not possible.
Regenerative energy may accumulate, and this must be either fed back into the supply
system or converted into heat using a braking resistor.
Figure 5-13
The total of the two torque setpoints is limited in the same way as the speed control torque
setpoint. Above the maximum speed (p1082), a speed limiting controller reduces the torque
limits in order to prevent the drive from accelerating any further.
A "real" torque control (with self-adjusting speed) is only possible in closed-loop but not
open-loop control for sensorless vector control (SLVC). In open-loop control, the torque
setpoint adjusts the setpoint speed via a ramp-function generator (integration time ~ p1499 x
p0341 x p0342). For this reason, encoderless torque control at standstill is only suitable for
applications that require an acceleration torque but no load torque (e.g. traction drives). This
restriction does not apply to torque control with sensor.
210
Closed-loop speed/torque control
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
Drive functions