Lenze 8400 TopLine - Manual (Page 274)

5 Motor control (MCTRL)
5.10 Parameterisable additional functions
274
Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
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5.10.7.2 Oscillation damping in the field weakening range
When the max. possible output voltage (full modulation) has been reached, a voltage dip in the DC
bus causes a voltage fluctuation in the motor. With load and during no-load operation this voltage
fluctuation can cause mechanical oscillations.
The "oscillation damping field weakening" adjustable in
C00236 serves to limit the maximum
output voltage. This can be used to always compensate voltage dips in the DC bus to the output
voltage (constant output voltage). This serves to prevent mechanical oscillations due to these
voltage dips.
• With the Lenze setting of C00236 the limitation of the output voltage is set so that voltage dips
in the DC bus in the output voltage for the single-phase and three-phase devices can largely be
compensated so that no speed oscillations may be expected. Thus, an adaptation of C00236 is
not required in the majority of cases.
• Maximum output voltage to be reached with Lenze setting of C00236 :
• Single-phase devices: 98.2 %
• Three-phase devices: 99.7 %

How to eliminate speed oscillations in the field weakening range:
1. Approach the area where the speed oscillations occur.
2. Reduce the speed oscillations by changing
C00236 step by step (increment 1).
3. These can be indicators for smooth running:
• Constant motor current characteristic
• Reduction of the mechanical oscillations in the bearing seat
Parameter Info Lenze setting
Value Unit
C00236 Oscillation damping field weakening
• Setting "0" ≡ 100 % output voltage can be reached
14

Note!
The limitation of the output voltage via C00236 in the extreme field weakening range
(high speeds) causes a reduction of the max. possible output torque (stalling torque).
• If the output torque to be reached in the extreme field weakening range is not
sufficient (motor is stalling too early), reduce the setting in C00236 .
With servo control (SC), the Lenze setting of C00236 should not be reduced. Otherwise
the field weakening control could not work optimally anymore (the behaviour at high
speeds may get worse). When servo control (SC) has been selected, the oscillation
damping in C00236 should never be set to "0".