Speed Pid Control; The Following Parameters Are Relevant For The Speed Control - Danfoss FC 300 Design Manual

FC 300 Design Guide

Speed PID Control

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The table shows the control configurations where the Speed Control is active.
Par. 1-00
Configuration
Mode
[0] Speed open
loop
[1] Speed
closed-loop
[2] Torque
[3] Process
open-loop
Note: "N.A." means that the specific mode is not available at all. "Not Active" means that the
specific mode is available but the Speed Control is not active in that mode.
Note: The Speed Control PID will work under the default parameter setting, but tuning the parameters
is highly recommended to optimize the motor control performance. The two Flux motor control
principles are specially dependent on proper tuning to yield their full potential.

The following parameters are relevant for the Speed Control:

Parameter
Feedback Par. 7-00
Speed PID Proportional
Gain Par. 7-02
Speed PID Integral Time
Par. 7-03
Speed PID Differentia-
tion Time Par. 7-04
Speed PID Diff. Gain
Limit Par. 7-05
Speed PID Lowpass
Filter Time Par. 7-06
Introduction to FC 300
Par. 1-01 Motor Control Principle
U/f VVCplus
Not Active Not Active
N.A.
ACTIVE
N.A. N.A.
Not Active
Description of function
Select from which input the Speed PID should get 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 value means quick reaction.
However, too low a value may lead to oscillations.
Provides a gain proportional to the rate of change of the feedback. A setting
of zero disables 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 large a filter time will
deteriorate the dynamic performance of the Speed PID control.
Practical settings of Par 7-06 taken from the number of pulses per revolution
on from encoder (PPR):
Encoder PPR
512
1024
2048
4096
MG.33.B6.22 - VLT is a registered Danfoss trademark
Flux sensorless
ACTIVE
N.A.
N.A.
ACTIVE
Par. 7-06
10 ms
5 ms
2 ms
1 ms
Flux w motor feedb
N.A.
ACTIVE
Not Active
ACTIVE
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