Pid Control; Speed Pid Control; Speed Pid Control Parameters - Danfoss VLT AutomationDrive FC 300 Design Manual

Product Introduction

3.4 PID Control

3.4.1 Speed PID Control

1-00 Configuration Mode 1-01 Motor Control Principle
U/f
[0] Speed open-loop Not Active
[1] Speed closed-loop N.A.
[2] Torque N.A.
[3] Process
Table 3.6 Control Configurations Where the Speed Control is Active
"N.A." means that the specific mode is not available. "Not Active" means that the specific mode is available but the Speed Control is not active in
that mode.
NOTICE!
The Speed Control PID works 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 particularly dependent on proper
tuning to yield their full potential.

3.4.2 Speed PID Control Parameters

Parameter
7-00 Speed PID Feedback Source
30-83 Speed PID Proportional Gain
7-03 Speed PID Integral Time
7-04 Speed PID Differentiation Time
7-05 Speed PID Diff. Gain Limit
7-06 Speed PID Lowpass Filter Time
Table 3.7 Relevant Parameters for the Speed PID Control
MG34S222
Design Guide
plus
VVC
Not Active
Active
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 feedback change. 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 dampens oscillations to 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 7-06 Speed PID Lowpass Filter Time taken from the number of pulses
per revolution from encoder (PPR):
Encoder PPR
512
1024
2048
4096
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
Flux sensorless Flux w/ enc. feedb
Active N.A.
N.A. Active
N.A. Not Active
Active Active
7-06 Speed PID Lowpass Filter Time
10 ms
5 ms
2 ms
1 ms
3 3
37