Lenze i950

13.8.2 Notch lter (band-stop lter)
Due to the high dynamic performance or limit frequency of the closed current control loop,
mechanic
al natural frequencies can be acvated which may lead to an unstable speed control
loop in the case of resonance.
To mask out or at least damp these resonant frequencies, two notch lters are integrated in
the speed control loop of the inverter. In the Lenze seng, these lters are switched o:
m m*
0x2944:6
0x2944:5
0x2944:4
0x2944:3
0x2944:2
0x2944:1
Use of the notch lters depending on the resonant frequency
WARNING!
Improperly set notch lters have a negave impact on the response and disturbance behav-
iour of the speed c
ontrol: increased overshoot of the motor speed in case of response behav-
iour and / or higher speed deviaons (extreme case: complete instability of the drive)
In the case of impairment,
▶
the drive that is sll running must either be coasted down by acvang the inverter disable
or immediately be brought to a standsll via a brake.
▶
the speed controller must be opmised again aerwards.
▶
the test procedure must be repeated.
Output frequency Use of notch lters
0...1/2 f
limit_speed_c
ontroller
No
1/2 f
limit_speed_controller...f_limit_speed-Controller
yes, with restricon
<f
limit_speed_controller
yes, without restricon
•
The not
ch lters are suitable for use with resonant frequencies equal to or higher than the
limit fr
equency of the speed controller:
•
Resonant frequencies ≥ f
limit_speed_controller
= 70 Hz ... 110 Hz
•
For resonant frequencies lower than the limit frequency of the speed controller, the use of
suitable speed proles with an S-shaped ramp is recommended.
Conguring the motor control
P
arameterise lter elements in the setpoint path
Notch lter (band-stop lter)
285