Danfoss VLT Midi Drive FC 280 Design Guide

2.5 PID Control
2.5.1 Speed PID Control
Parameter 1-00 Conguration Mode
Parameter 1-01 Motor Control Principle
U/f
VVC
+
[1] Speed closed loop
Not available
1)
Active
Table 2.5 Control Congurations, Active Speed Control
1) Not available indicates that the
specic mode is not available at all.
The following parameters are relevant for the speed control:
Parameter Description of function
Parameter 7-00 Speed PID Feedback Source Select from which input the speed PID gets its feedback.
Parameter 7-02 Speed PID Proportional Gain The higher the value, the quicker the control. However, too high a value may lead to
oscillations.
Parameter 7-03 Speed PID Integral Time Eliminates steady state speed error. Lower values mean quicker reaction. However, too low
a value may lead to oscillations.
Parameter 7-04 Speed PID Dierentiation Time Provides a gain proportional to the rate of change of the feedback. A setting of 0 disables
the dierentiator.
Parameter 7-05 Speed PID Di. Gain Limit If there are quick changes in reference or feedback in a given application, which means
that the error changes swiftly, the dierentiator may soon become too dominant. This is
because it reacts to changes in the error. The quicker the error changes, the stronger the
dierentiator gain is. The dierentiator gain can thus be limited to allow setting of the
reasonable dierentiation time for slow changes and a suitably quick gain for quick
changes.
Parameter 7-06 Speed PID Lowpass Filter Time A low-pass lter that dampens oscillations on the feedback signal and improves steady
state performance. However, too long a lter time deteriorates the dynamic performance of
the speed PID control.
Practical settings of parameter 7-06 Speed PID Lowpass Filter Time taken from the number of
pulses per revolution on from encoder (PPR):
Encoder PPR Parameter 7-06 Speed PID Lowpass Filter
Time
512 10 ms
1024 5 ms
2048 2 ms
4096 1 ms
Table 2.6 Speed Control Parameters
Product Overview Design Guide
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Danfoss VLT Midi Drive FC 280 Specifications

General

Brand	Danfoss
Model	VLT Midi Drive FC 280
Category	DC Drives
Language	English