Danfoss VLT AutomationDrive FC 300 Series Programming Manual page 101

Parameter Descriptions
7-06 Speed PID Lowpass Filter Time
Range:
3 3
100
®
VLT
Function:
example, if a time constant (τ) of 100 ms is
programmed, the cut-off frequency for the
low-pass filter will be 1/0.1= 10 RAD/sec.,
corresponding to (10/2 x π) = 1.6 Hz. The
PID regulator only regulates a feedback
signal that varies by a frequency of less than
1.6 Hz. If the feedback signal varies by a
higher frequency than 1.6 Hz, the PID
regulator does not react.
Practical settings of 7-06 Speed PID Lowpass
Filter Time taken from the number of pulses
per revolutions from encoder:
Encoder PPR 7-06 Speed PID
Lowpass Filter Time
512 10 ms
1024 5 ms
2048 2 ms
4096 1 ms
Table 3.21
Note that severe filtering can be detrimental
to dynamic performance.
This parameter is used with 1-00 Configu-
ration Mode [1] Speed closed loop and [2]
Torque control.
The filter time in flux sensorless must be
adjusted to 3-5 ms.
MG33ME02 - VLT
AutomationDrive Programmming Guide
Feedback
Disturbed feedback signal
Feedback
Filtered feedback signal
Illustration 3.45
®
is a registered Danfoss trademark
0.6
Lowpass lter
f = 10 Hz
g
0.6
t (Sec.)
t (Sec.)