Danfoss VLT AutomationDrive FC 301 Programming Manual page 257

VLT AutomationDrive FC 301/302
Programming Guide
Enter the speed controller differentiation time. The differentiator does not react to constant error. It provides gain proportional to
the rate of change of the speed feedback. The quicker the error changes, the stronger the gain from the differentiator. The gain is
proportional with the speed at which errors change. Setting this parameter to 0 disables the differentiator. This parameter is used
with parameter 1-00 Configuration Mode, [1] Speed closed loop control.
Parameter 7-05 Speed PID Diff. Gain Limit
Table 451: Parameter 7-05 Speed PID Diff. Gain Limit
7-05 Speed PID Diff. Gain Limit
Default value: 5
Conversion index: -1
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.
Parameter 7-06 Speed PID Lowpass Filter Time
Table 452: Parameter 7-06 Speed PID Lowpass Filter Time
7-06 Speed PID Lowpass Filter Time
Default value: Size related
Conversion index: -4
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 oscil-
lations 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 453: Speed PID Low-pass Filter Time
Encoder PPR
512
1024
2048
4096
Danfoss A/S © 2022.12
Parameter type: Range, 1 - 20
Data type: Uint16
Parameter type: Range, 0.1 - 100 ms
Data type: Uint16
N O T I C E
Parameter 7-06 Speed PID Lowpass Filter Time [ms]
10
5
2
1
Parameter Descriptions
Setup: All setups
Change during operation: True
Setup: All setups
Change during operation: True
AU275636650261en-000101 / 130R0334 | 257