Danfoss VLT AutomationDrive FC 300 Series, Programming Manual, Page: 101 / 211

7-06 Speed PID Lowpass Filter Time
Range: 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.
0.6
0.6
f
g
= 10 Hz
175ZA293.11
Feedback
Disturbed feedback signal
t (Sec.)
t (Sec.)
Filtered feedback signal
Lowpass filter
Feedback
Illustration 3.45
Parameter Descriptions
VLT
®
AutomationDrive Programmming Guide
100 MG33ME02 - VLT
®
is a registered Danfoss trademark
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