Danfoss FC 300 Series User Manual

7-06 Speed PID Lowpass Filter Time
Range: Function:
Application
dependent
*
[1.0 -
100.0
ms]
Set a time constant for the speed control
low-pass filter. The low-pass filter
improves steady-state performance and
dampens oscillations on the feedback
signal. This is an advantage if there is a
great amount on noise in the system; see
figure below. For 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 frequency
higher 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
Note that severe filtering can be
detrimental to dynamic performance.
This parameter is used with 1-00 Configu-
ration Mode Speed closed-loop [1] and
Torque [2] control.
The filter time in flux sensorless must be
adjusted to 3–5 ms.
Parameter Descriptions FC 300 Programming Guide
3-76 MG.33.MA.22 - VLT
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is a registered Danfoss trademark
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3

Danfoss FC 300 Series Specifications

General

Brand	Danfoss
Model	FC 300 Series
Category	DC Drives
Language	English