16 PID Controls
16.1 Speed PID Controls
Parameter 1-00 Configu-
ration Mode
Parameter 1-01 Motor Control Principle
U/f
VVC
+
Flux sensorless
Flux w/ enc. feedb
[0] Speed open loop
Not Active
Not Active
Active
–
[1] Speed closed loop
–
Active
–
Active
[2] Torque
–
–
–
Not Active
[3] Process
–
Not Active
Active
Active
Table 16.1 Control Configurations Where the Speed Control is Active
“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 2 flux motor control principles depend on proper tuning to yield their full
potential.
16.1.1 Speed PID Control Parameters
Parameter
Description of function
Parameter 7-00 Speed PID Feedback Source
Selects from which input the speed PID gets its feedback.
Parameter 30-83 Speed PID Proportional Gain
The higher the value - the quicker the control. However, too high a value can lead to
oscillations.
Parameter 7-03 Speed PID Integral Time
Eliminates steady state speed error. Lower value means quick reaction. However, too low a
value can lead to oscillations.
Parameter 7-04 Speed PID Differentiation Time
Provides a gain proportional to the rate of feedback change. A setting of 0 disables the
differentiator.
Parameter 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 can become too dominant. 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.
Parameter 7-06 Speed PID Lowpass Filter Time
A low-pass filter dampens oscillations to the feedback signal and improves steady state
performance. However, too large 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 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 16.2 Relevant Parameters for the Speed PID Control
16.1.2 Example of How to Program the Speed Control
In this case, the speed PID control is used to maintain a constant motor speed regardless of the changing load on the
motor. The required motor speed is set via a potentiometer connected to terminal 53. The speed range is 0–1500 RPM
corresponding to 0–10 V over the potentiometer. A switch connected to terminal 18 controls the starting and stopping.
PID Controls
Design Guide
MG37N102
Danfoss A/S © 6/2016 All rights reserved.
143
16
16
