Lenze 8400 - Page 247

Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23 247
5 Motor control (MCTRL)
5.9 Servo control (SC)
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Other functions for differential setpoint feedforward control
From version V12.00.00 onwards, the following additional functions are available for differential
setpoint feedforward control (torque feedforward control):
•In C00653/1
, the sensitivity of setpoint feedforward control can be adapted.
•In C00654/1
, alternatively to the nSpeedSetValue_a process signal, the new
nSpeedSetValueInertia_a process signal for the setpoint feedforward control can be selected at
the LS_MotorInterface
SB. Via the nSpeedSetValueInertia_a process signal, an optional input
value (e.g. setpoint of the position or process controller) for the torque feedforward control can
be specified.
•For bTorqueModeOn = TRUE, the setpoint feedforward control is added to the torque setpoint
nTorqueSetValue_a. In this way, feedforward control of torque is also possible for torque-
controlled operation (e.g. for winder applications).
 Stop!
In the Lenze setting of C00654/1, the speed setpoint of the speed controller
(nSpeedSetValue_a) is used for the torque feedforward control which is why it is also
called "differential setpoint feedforward control". A very sharp change of the speed
setpoint at the speed controller thus causes a strong torque impulse at the machine!
Causes for a very sharp change of the speed setpoint of the speed controller:
• A control creates the setpoint ramp itself and the speed setpoint is only written every
20 ms to the drive. (In this case, the speed setpoint is changed every 20 ms.)
• Recommendation: Deactivate the torque feedforward control for the speed
setpoint in C00654/1
if the speed setpoint changes very sharply or the mass inertia
is unknown (e.g. in case of hoists)!
• The reference speed C0011
is much higher than the rated motor speed set in C0087.
• Recommendation: Deactivate the torque feedforward control for the speed
setpoint in C00654/1
if the reference speed C0011 5 times higher than the rated
motor speed C0087
.