Danfoss VLT FC 102 Programming Manual page 219

Programming Guide | VLT® HVAC Drive FC 102
Data type: Uint16
Set a limit for the gain provided by the differentiator. Consider limiting the gain at higher frequencies. For example, set up a pure D-
link at low frequencies and a constant D-link at higher frequencies. This parameter is used with parameter 1-00 Configuration Mode, [1]
Speed closed loop control.
7-06 Speed PID Lowpass Filter Time
Default value:
Size related
Setup: All setups
Data type:
Uint16
Severe filtering can be detrimental to dynamic performance. This parameter is used with parameter 1-00 Configuration Mode, [1]
Speed closed loop and [2] Torque control. Adjust the filter time in flux sensorless to 3–5 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 of noise in the system. For example, if a time constant (τ) of 100 ms
is programmed, the cut-off frequency for the low-pass filter is 1/0.1 = 10 RAD/s, 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 parameter 7-06 Speed PID Lowpass Filter Time taken from the number of
pulses per revolutions from encoder:
Table 34: Speed PID Low-pass Filter Time
Encoder PPR
512
1024
2048
4096
© 2024.10
Change during operation:
Parameter type:
Conversion index:
Change during operation:
NOTICE
Parameter 7-06 Speed PID Lowpass Filter Time [ms]
10
5
2
1
Parameter Descriptions
True
Range, 0.1 - 100 ms
-4
True
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