Before carrying out the auto-tuning, set the following
parameters according to the load inertia:
•
Parameter 3-41 Ramp 1 Ramp Up Time.
•
Parameter 3-42 Ramp 1 Ramp Down Time.
Or
•
Parameter 3-51 Ramp 2 Ramp Up Time.
•
Parameter 3-52 Ramp 2 Ramp Down Time.
If PID auto-tuning is carried out with slow ramp times, the
auto-tuned parameters typically result in slow control.
Before activating PID auto-tuning, remove excessive
feedback sensor noise using the input lter (parameter
groups 6-** Analog In/Out, 5-5* Pulse Input and 26-** Analog
I/O Option MCB 109, parameter 6-16 Terminal 53 Filter Time
Constant, parameter 6-26 Terminal 54 Filter Time Constant,
parameter 5-54 Pulse Filter Time Constant #29,
parameter 5-59 Pulse Filter Time Constant #33). To obtain the
most accurate controller parameters, carry out PID auto-
tuning when the application runs in typical operation, that
is, with a typical load.
SPC auto-tuning
SPC initiates a tuning of DRC. If feedback from the system
determines the system to be 2
nd
order, auto-tuning
proceeds automatically with tuning of PID parameters. If
SPC discards the DRC, it is shown by the process bar going
to step 4.
DRC assumes that the frequency converter’s target
applications can be generically modeled as 1
st
order plus
dead-time systems. DRC auto-tuning is providing the
feedback for calculation.
•
Ï„ = time constant of process system K
p
process
system gain.
•
θ = time delay between input and output DRC
can only be set up by using SPC.
20-70 Closed Loop Type
Option: Function:
Select the application response
speed if it is known. The default
setting is sucient for most
applications. A more precise value
decreases the time needed for
carrying out PID adaptation. The
setting has no impact on values of
parameters and only aîš„ects the
auto-tuning speed.
[0] * Auto Takes 30–120 s to complete.
[1] Fast Pressure Takes 10–60 s to complete.
[2] Slow Pressure Takes 30–120 s to complete.
[3] Fast
Temperature
Takes 10–20 minutes to complete.
[4] Slow
Temperature
Takes 30–60 minutes to complete.
20-71 PID Performance
Option: Function:
[0] * Normal Normal setting of this parameter is
suitable for pressure control in fan
systems.
[1] Fast Fast setting is used in pumping
systems where a faster control
response is wanted.
20-72 PID Output Change
Range: Function:
0.10* [0.01 - 0.50 ] This parameter sets the magnitude
of step change during auto-tuning.
The value is a percentage of full
speed. That is, if maximum output
frequency in parameter 4-13 Motor
Speed High Limit [RPM]/
parameter 4-14 Motor Speed High
Limit [Hz] is set to 50 Hz, 0.10 is
10% of 50 Hz, which is 5 Hz. Set
this parameter to a value resulting
in feedback changes of 10–20% for
best tuning accuracy.
20-73 Minimum Feedback Level
Range: Function:
-999999
ProcessCtrl
Unit*
[ -999999.999
- par. 20-74
ProcessCtrlUnit
]
Enter the minimum allowable
feedback level in user units as
dened in
parameter 20-12 Reference/Feedback
Unit. If the level drops below
parameter 20-73 Minimum Feedback
Level, auto-tuning is aborted and an
error message appears in the LCP.
20-74 Maximum Feedback Level
Range: Function:
999999
ProcessCtrl
Unit*
[ par. 20-73 -
999999.999
ProcessCtrlUnit
]
Enter the maximum allowable
feedback level in user units as
dened in
parameter 20-12 Reference/Feedback
Unit. If the level rises above
parameter 20-74 Maximum Feedback
Level, auto-tuning is aborted and an
error message appears in the LCP.
20-79 PID Autotuning
Option: Function:
This parameter starts the auto-
tuning sequence. Once the auto-
tuning has successfully completed
and the settings have been
accepted or rejected by pressing
[OK] or [Cancel] at the end of
Parameter Descriptions Programming Guide
M0010001 Danfoss A/S © 10/2019 All rights reserved. 185
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