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2.5 PID Control
2.5.1 Speed PID Control
1-00 Configuration Mode
1-01 Motor Control Principle
U/f
VVC
+
[0] Speed open loop
Not Active
1)
Not Active
[1] Speed closed loop
Not Available
2)
ACTIVE
[2] Torque
Not Available
Not Active
[3] Process
Not Active
Not Active
Table 2.4 Control Configurations, Active Speed Control
1) Not Active indicates that the specific mode is available but the speed control is not active in that mode.
2) Not Available indicates that the specific mode is not available at all.
The following parameters are relevant for the speed control:
Parameter
Description of function
7-00 Speed PID Feedback Source
Select from which input the Speed PID should get its feedback.
7-02 Speed PID Proportional Gain
The higher the value, the quicker the control. However, too high a value may lead to
oscillations.
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.
7-04 Speed PID Differentiation Time
Provides a gain proportional to the rate of change of the feedback. A setting of 0 disables
the differentiator.
7-05 Speed PID Diff. Gain Limit
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.
7-06 Speed PID Lowpass Filter Time
A low-pass filter that dampens oscillations on the feedback signal and improves steady
state performance. However, too long a filter time will deteriorate the dynamic
performance of the speed PID control.
Practical settings of
7-06 Speed PID Lowpass Filter Time
taken from the number of pulses
per revolution on from encoder (PPR):
Encoder PPR
7-06 Speed PID Lowpass Filter Time
512
10 ms
1024
5 ms
2048
2 ms
4096
1 ms
Table 2.5 Speed Control Parameters
Product Overview
Design Guide
MG06B402
Danfoss A/S © 09/2014 All rights reserved.
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