Lenze E94AxPExxxx - Manual (Page 239)

Lenze · 9400 Servo PLC· Reference manual · DMS 4.0 EN · 11/2013 · TD05/06
239
6 Motor interface
6.6 V/f control (VFCplus)
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6.6.2.3 Parameterising oscillation damping
The oscillation damping serves to reduce the oscillations during no-load operation which are caused
by energy oscillating between the mechanical system (mass inertia) and the electrical system (DC
bus). Furthermore, the oscillation damping can also be used to compensate resonances.
Function
The determination of the oscillation is based on the active current. In order to obtain the alternating
component of the active current, this current is differentiated. This signal is then passed through a
PT1 filter.
• The base frequency of the PT1 filter has to be set in such a way that the oscillation can be
damped and higher-frequency components are filtered out of the signal. For this purpose the
time constant ( C00968 ) is used.
• C00967 serves to parameterise the gain of the oscillation signal. The maximum amplitude of
the frequency change determined by the oscillation damping is set via C00969 .
• Oscillation damping is only active if the setpoint speed is greater than 10 rpm and the DC-bus
voltage exceeds a value of 100 V.
• In the lower speed range, the oscillation damping may have a negative impact on the
concentricity factor.
• Therefore, from software version V5 onwards, a ramp end frequency can be set in C00970 up
to which the gain of the oscillation damping ( C00967 ) from 10 rpm is slowly increased with
increasing rotational frequency.

Note!
Observe the following restrictions:
• Oscillations occurring sporadically cannot be damped.
• Damping is possible only for constant oscillations at a steady-state operating point.
• The oscillation damping is not suitable for oscillations occurring during dynamic
processes (e.g. accelerations or load changes).
C00968
C00967
C00969
C00970
Actual value
of active current
Set value
of rotating frequency