Parameters: 21-** Extended Closed Loop - Danfoss VLT Refrigeration Drive FC 103 Programming Manual

Parameter Description
3.17 Parameters: 21-** Extended Closed
Loop
3.17.1 21-** Ext. Closed Loop
®
The VLT Refrigeration Drive FC 103 offers 3 extended
closed-loop PID controllers in addition to the PID
controller. These can be configured independently to
control either external actuators (valves, dampers, and so
on.) or be used with the internal PID controller to improve
the dynamic responses to setpoint changes or load distur-
bances.
The extended closed-loop PID controllers may be intercon-
nected or connected to the PID closed-loop controller to
form a dual-loop configuration.
To control a modulating device (for example a valve
motor), this device must be a positioning servo motor with
built-in electronics accepting either a 0–10 V (signal from
®
VLT Analog I/O Option MCB 109) or a 0/4–20 mA (signal
®
from control card and/or VLT
101) control signal.
The output function can be programmed in the following
parameters:
•
Control card, terminal 42: Parameter 6-50 Terminal
42 Output (setting [113]...[115] or [149]...[151], Ext.
Closed Loop 1/2/3
•
®
VLT General Purpose I/O MCB 101, terminal
X30/8: Parameter 6-60 Terminal X30/8 Output,
(setting [113]...[115] or [149]...[151], Ext. Closed
Loop 1/2/3
•
®
VLT Analog I/O Option MCB 109, terminal
X42/7...11: Parameter 26-40 Terminal X42/7 Output,
parameter 26-50 Terminal X42/9 Output,
parameter 26-60 Terminal X42/11 Output (setting
[113]...[115], Ext. Closed Loop 1/2/3
®
VLT General Purpose I/O MCB 101 and VLT
Option MCB 109 are optional cards.
3.17.2 21-0* Extended CL Autotuning
The extended closed-loop PID controllers can each be auto
tuned, simplifying and saving time during commissioning,
while ensuring accurate PID control adjustment.
To use PID auto tuning, configure the relevant extended
PID controller for the application.
Use a graphical LCP to react on messages during the auto
tuning sequence.
MG16H202
Programming Guide
General Purpose I/O MCB
®
Analog I/O
Danfoss A/S © 05/2016 All rights reserved.
Enabling auto tuning, parameter 21-09 PID Autotuning puts
the relevant PID controller into PID auto tuning mode. The
LCP then provides on-screen instructions.
PID auto tuning introduces step changes and then
monitors the feedback. Based on the feedback response,
the following required values are calculated:
•
PID proportional gain.
- Parameter 21-21 Ext. 1 Proportional Gain
for EXT CL 1.
-
Parameter 21-41 Ext. 2 Proportional Gain
for EXT CL 2.
- Parameter 21-61 Ext. 3 Proportional Gain
for EXT CL 3.
•
Integral time.
- Parameter 21-22 Ext. 1 Integral Time for
EXT CL 1.
- Parameter 21-42 Ext. 2 Integral Time for
EXT CL 2.
- Parameter 21-62 Ext. 3 Integral Time for
EXT CL 3 are calculated.
The PID differentiation time is set to 0 in the following
parameters:
•
Parameter 21-23 Ext. 1 Differentation Time for EXT
CL 1.
•
Parameter 21-43 Ext. 2 Differentation Time for EXT
CL 2.
•
Parameter 21-63 Ext. 3 Differentation Time for EXT
CL 3 are set to value 0 (zero).
•
Parameter 21-20 Ext. 1 Normal/Inverse Control for
EXT CL 1.
•
Parameter 21-40 Ext. 2 Normal/Inverse Control for
EXT CL 2.
•
Parameter 21-60 Ext. 3 Normal/Inverse Control for
EXT CL 3 are determined during the tuning
process.
These calculated values are presented on the LCP and can
either be accepted or rejected. Once accepted, the values
are written to the relevant parameters, and PID auto
tuning mode is disabled in parameter 21-09 PID Autotuning.
Depending on the system being controlled, the time
required to carry out PID auto tuning could be several
minutes.
Before activating the PID auto tuning, remove excessive
feedback sensor noise using the input filter (parameter
groups 5-5* Pulse Input, 6-** Analog In/Out and 26-** Analog
I/O Option MCB 109, terminal 53/54 filter time constant,
and pulse filter time constant #29/33) before activating PID
auto tuning.
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