Limiting The Torque Setpoint - Siemens MICROMASTER 440 Operating Instructions Manual

3 Functions
The sum of both torque setpoints is limited in the same way as the torque setpoint
of the speed control (refer to Section 3.23.2.5). Above the maximum speed (plus 3
%), a speed limiting controller reduces the torque limits in order to prevent the drive
accelerating any further.
A "real" closed-loop torque control (with automatically set speed) is only possible in
the closed-loop controlled range but not in the open-loop controlled range. In the
open-loop controlled range, the torque setpoint changes the setpoint speed
through a ramp-up integrator (integration time ~ P1499 * P0341 * P0342). This is
the reason that sensorless closed-loop torque control in the area around standstill
(0 speed) is only suitable for applications which require an accelerating torque
there and not a load torque (e.g. traversing drives). For closed-loop torque control
with sensors, this restriction does not apply.
If the closed-loop torque control is active, and a fast stop command (OFF3) is
output, then the system automatically changes-over to closed-loop speed control
and the drive is braked. If a normal stop command (OFF1) is output, there is no
changeover. Instead, the system waits until a higher-level control has brought the
drive to a standstill, in order to inhibit the pulses there. This is necessary in order to
allow the master and slave drives to be shut down together. For P1300 = 22 or 23,
for OFF1, the drive is directly powered-down (as for OFF2).
3.23.2.5

Limiting the torque setpoint

Parameter range:
Warnings
Faults
Function chart number:
All of the following limits act on the torque setpoint which is either entered at the
speed controller output for closed-loop speed control or as torque input for closed-
loop torque control. The minimum is used from the various limits. This minimum is
cyclically computed in the drive inverter and displayed in parameters r1538, r1539.
r1538
r1539
This means that these cyclic values limit the torque setpoint at the speed controller
output / torque input and indicate the instantaneously maximum possible torque. If
the torque setpoint is limited in the drive inverter, then this is displayed using the
following diagnostic parameters
r1407 bit 08 Upper torque limit active
r1407 bit 09 Lower torque limit active
254
P1520 – P1531
P0640, r0067
r1407 bit 08, r1407 bit 09
-
-
FP7700, FP7710
Upper torque limit
Lower torque limit
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0
Issue 10/06