Lenze 8400 TopLine - Manual (Page 253)

Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
253
5 Motor control (MCTRL)
5.9 Servo control (SC)
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Field feedforward control
To have enough voltage reserve available for dynamic acceleration processes, a timely weakening
of the field is required. The field weakening is controlled by the field feedforward control.
The field feedforward control reciprocally reduces the magnetising current from the V/f base
frequency ( C00015 ) on. The starting point of the reduction can be shifted to low frequencies via the
field feedforward control ( C00576 ). Thus, more voltage reserve is available for acceleration
processes.
The field feedforward control (
C00576 ) must be specified in %, based on the rated slip of the
machine.

Tip!
Generally, the Lenze setting is sufficient for most applications.
• We recommend to increase the field feedforward control for applications with very
dynamic acceleration processes in the field weakening range.
• Reduce the field feedforward control for very slow applications if necessary.
Parameter Info Lenze setting
Value Unit
C00576 SC: Field feedforward control 200.0 %

Note!
The function of the field feedforward control and thus the field weakening control
requires a correct setting of the V/f base frequency ( C00015 ).
• The selection of the motor from the »Engineer« motor catalogue and the motor
parameter identification serve to set the V/f base frequency correctly.
• When third-party motors are entered, either the V/f base frequency ( C00015 ) has to
be calculated manually or a motor parameter identification has to be carried out.
 Adapting the V/f base frequency ( 164)
 Automatic motor data identification ( 141)
Due to an error in the device software, the field feedforward control of the servo control
only operates properly if the V/f base frequency ( C00015 ) is reduced by the following
factor after being set:
• 400-V devices: Factor 0.173
• 230-V devices: Factor 0.34
The same factor has to be considered for the field feedforward control ( C00576 ).
From version 14.00.00 , the control parts can be called for an optimum jerk-free
transition to the field weakening range in a 500- μ s cycle. For this purpose, bit 5 has to be
set to "1" int in C02864/1 .
• With this setting, C00015 and C00576 do not have any influence anymore on the field
feedforward control.
• We recommend this setting for new applications.