Watson-Marlow MM440 - Manual (Page 254)

3 Functions Issue 10/06
MICROMASTER 440 Operating Instructions
254 6SE6400-5AW00-0BP0
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: P1520 – P1531
P0640, r0067
r1407 bit 08, r1407 bit 09
Warnings -
Faults -
Function chart number:
FP7700, FP7710
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.
¾
r1538 Upper torque limit
¾ r1539 Lower torque limit
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
¾
r1407 bit 08 Upper torque limit active
¾ r1407 bit 09 Lower torque limit active