Lenze i700 - Setting the Oscillation Damping

Lenze · i700 servo inverter · reference manual · DMS 3.0 EN · 06/2016 · TD06 156
5 Motor control & motor settings
5.14 Parameterising the V/f characteristic control
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5.14.7 Setting the 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.
Identification of the oscillation
Before the oscillation damping can be parameterised, the oscillation has to be identified. One
option is to examine the motor current at switched-off oscillation damping (gain = 0 %). The
oscilloscope function of the »PLC Designer« serves to record the following currents:
• Q current 0x2DD1:2
/ 0x35D1:2
•Total current 0x2DD1:5
or 0x35D1:5
Passive loads cause a constant current in continuous operation with constant speed (steady-state
operation). If the drive oscillates, this oscillation also takes place in the motor current. Thus, it is
possible to determine the frequency and amplitude of the oscillation by means of the AC
component in the motor current. In the following, this AC component is called "current oscillation".
 Note!
Observe the following restrictions:
• Damping is possible only for constant oscillations at a steady-state operating point.
• Oscillations occurring sporadically cannot
be damped.
• Oscillation damping is not
suitable for oscillations occurring during dynamic
processes (e.g. accelerations or load changes).
• 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.
0x2DD1:2 | 0x35D1:2
0x2B0A:2 | 0x330A:2
0x2B0A:1 | 0x330A:1
0x2B0A:4 | 0x330A:4
0x2B0A:3 | 0x330A:3
Q-current (iq): Actual current
Filter time
Gain
Ramp-end frequency
Limitation
Set value
mot. frequency
Oscillation damping