Danfoss VLT CDS 303 User Manual

6.8 Par. Group 7 - Controllers
7-06 Speed PID Lowpass Filter Time
Range: Function:
Size
related*
[0.1
- 100
ms]
Set a time constant for the speed control low-
pass lter. The low-pass lter 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 6.10. For example, if a time
constant (τ) of 100 ms is programmed, the
cut-o frequency for the low-pass lter will be
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:
Encoder PPR Parameter 7-06 Spee
d PID Lowpass Filter
Time
512 10 ms
1024 5 ms
2048 2 ms
4096 1 ms
NOTICE!
Severe ltering can be detrimental to dynamic
performance.
This parameter is used with parameter 1-00 Conguration
Mode [1] Speed closed loop and [2] Torque control.
The lter time in ux 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 lter
Feedback
Figure 6.10 Feedback Signal
6.8.1 7-2* Process PID Feedback
Select the feedback sources for the Process PID Control,
and how this feedback should be handled.
Parameter Descriptions
VLT
®
Compressor Drives CDS 302/CDS 303
76 Danfoss A/S © Rev. 2013-07-03 All rights reserved. MG34M422
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6

Danfoss VLT CDS 303 Specifications

General

Brand	Danfoss
Model	VLT CDS 303
Category	DC Drives
Language	English