Danfoss FC 300 Design Manual page 185

FC 300 Design Guide
higher frequencies, limiting the gain may be use-
ful. For example, set up a pure D-link at low fre-
quencies and a constant D-link at higher frequen-
cies. This parameter is used with par. 1-00 Speed
closed loop [1] control.
7-06 Speed PID Lowpass Filter Time
Value:
1.0 - 100.0 ms
Function:
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 illus-
tration 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 p) = 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.
Note that severe filtering can be detrimental to
dynamic performance.
This parameter is used with par. 1-00 Speed
closed loop [1] and Torque [2] control.
7-08 Speed PID Feed Forward Factor
Value:
0 - 500%
Function:
The reference signal bypasses the speed control-
ler by the amount specified. This feature increases
factory setting
How to Programme
10.0ms
0%
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MG.33.B7.02 - VLT is a registered Danfoss trademark
the dynamic performance of the speed control
loop.
7-2* Process Ctrl. Feedb.
Select the feedback sources for the Process PID
Control, and how this feedback should be handled.
7-20 Process CL Feedback 1 Source
Value:
No function
Analog input 53
Analog input 54
Frequency input 29 (FC 302 only)
Frequency input 33
Bus feedback 1
Bus feedback 2
Analog input X30/11
Analog input X30/12
Function:
The effective feedback signal is made up of the
sum of up to two different input signals.
Select which frequency converter input should be
treated as the source of the first of these signals.
The second input signal is defined in par. 7-22.
7-22 Process CL Feedback 2 Source
Value:
No function
Analog input 53
Analog input 54
Frequency input 29 (FC 302 only)
Frequency input 33
Bus feedback 1
Bus feedback 2
Analog input X30/11
Analog input X30/12
Function:
The effective feedback signal is made up of the
sum of up to two different input signals. Select
which frequency converter input should be treated
as the source of the second of these signals. The
first input signal is defined in par. 7-21.
value for use in communication via serial communication port
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