Pid Control; Speed Pid Control - Danfoss VLT Midi Drive FC 280 Design Manual

Product Overview

2.5 PID Control

2.5.1 Speed PID Control

Parameter 1-00 Configuration Mode
[1] Speed closed loop
Table 2.5 Control Configurations, Active Speed Control
1) Not available indicates that the specific mode is not available at all.
The following parameters are relevant for the speed control:
Parameter
Parameter 7-00 Speed PID Feedback Source
Parameter 7-02 Speed PID Proportional Gain
Parameter 7-03 Speed PID Integral Time
Parameter 7-04 Speed PID Differentiation Time Provides a gain proportional to the rate of change of the feedback. A setting of 0 disables
Parameter 7-05 Speed PID Diff. Gain Limit
Parameter 7-06 Speed PID Lowpass Filter Time
Table 2.6 Speed Control Parameters
MG07B102
Design Guide
Parameter 1-01 Motor Control Principle
U/f
Not available 1)
Description of function
Select from which input the speed PID gets its feedback.
The higher the value, the quicker the control. However, too high a value may lead to
oscillations.
Eliminates steady state speed error. Lower values mean quicker reaction. However, too low
a value may lead to oscillations.
the differentiator.
If there are quick changes in reference or feedback in a given application, which means
that the error changes swiftly, the differentiator may soon become too dominant. This is
because it reacts to changes in the error. The quicker the error changes, the stronger the
differentiator gain is. The differentiator gain can thus be limited to allow setting of the
reasonable differentiation time for slow changes and a suitably quick gain for quick
changes.
A low-pass filter that dampens oscillations on the feedback signal and improves steady
state performance. However, too long a filter 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
512
1024
2048
4096
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Active
Parameter 7-06 Speed PID Lowpass Filter
Time
10 ms
5 ms
2 ms
1 ms
2 2
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