Lenze 8400 TopLine - Manual (Page 224)

5 Motor control (MCTRL)
5.8 Sensorless control for synchronous motors (SLPSM)
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Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
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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!
A very sharp change of the speed setpoint of the speed controller occurs if 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.)
Deactivate the speed 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)!