Setting The Current Setpoint Filter (Band-Stop Filter) - Lenze 8400 StateLine C Reference Manual

5.8.4.4

Setting the current setpoint filter (band-stop filter)

Due to the high dynamic performance/limit frequency of the closed current control loop,
mechanical natural frequencies can be activated which may lead to an unstable speed
control loop.
Parameter
C00270
C00271
C00272
 In the default setting of 0 db of the filter depth (C00272), the current setpoint filter is
switched off.
Setting of the current setpoint filter
Since the frequency response of the speed controlled system is only rarely known to such
an extent that the current setpoint filter can be adjusted to the controlled system in the
run-up, the following example describes how to set the current setpoint filter.

How to set the current setpoint filter:
1. Optimise current
2. Optimise speed
3. Measure the oscillation frequency (observe current or speed).
4. Set the measured oscillation frequency in
5. Set "25%" of the filter frequency in
• Example: Filter frequency = 200 Hz  filter width = 50 Hz.
6. Set "40 dB" in
• If the filter depth is set to "0 dB" (default setting), the filter is not active.

Note!
Readjust the speed controller after setting the current setpoint filter.
Optimise speed controller
Firmware ≤ 11.00 - DMS 8.0 EN - 10/2011
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Sensorless control for synchronous motors (SLPSM)
To mask out or at least damp these resonant frequencies, a so-called
current setpoint filter is integrated into the speed control loop of the
controller.
Info
SC: Freq. current setpoint filter
SC: Current setpoint filter width
SC: Current setpoint filter depth
controller.
( 182)
controller.
( 183)
C00272 as filter depth.
. ( 183)
L
8400 StateLine C | Reference manual
C00270 as filter frequency.
C00271 as filter width.
Motor control (MCTRL)
Lenze setting
Value Unit
200.0 Hz
0.0 Hz
0 dB
189