Parameters 21-** Extended Closed Loop - Danfoss VLT AQUA Drive FC 200 Programming Manual

Parameter Description
3.18 Parameters 21-** Extended Closed
Loop
The offers three extended closed-loop PID controllers in
addition to the PID controller. These can be configured
independently to control either external servos (valves,
dampers, etc.) or be used together with the internal PID
controller to improve the dynamic responses to setpoint
changes or load disturbances.
The extended closed-loop PID controllers may be intercon-
nected or connected to the PID closed-loop controller to
form a dual loop configuration.
In order to control a modulating device (e.g., a valve
motor), this device must be a positioning servo-motor with
built-in electronics which accepts either a 0–10 V (signal
from analog I/O card MCB 109) or a 0/4–20 mA (signal
from the control card and/or general purpose I/O card
MCB 101) control signal.
The output function can be programmed in the following
parameters:
•
Control Card, terminal 42: 6-50 Terminal 42 Output
(setting [113]...[115] or [149]...[151], Ext. Closed-
loop 1/2/3
•
General Purpose I/O card MCB 101, terminal
X30/8: 6-60 Terminal X30/8 Output, (setting [113]...
[115] or [149]...[151], Ext. Closed-loop 1/2/3
•
Analog I/O card MCB 109, terminal X42/7...11:
26-40 Terminal X42/7 Output, 26-50 Terminal X42/9
Output, 26-60 Terminal X42/11 Output (setting
[113]...[115], Ext. Closed-loop 1/2/3
The general purpose I/O card and the analog I/O card are
optional cards.
3.18.1 21-0* Extended CL autotuning
The extended PID Closed-loop PID controllers can each be
auto-tuned, simplifying and saving time during commis-
sioning, while ensuring accurate PID control adjustment.
To use PID autotuning it is necessary for the relevant
extended PID controller to have been configured for the
application.
A graphical Local Control Panel (LCP) must be used in
order to react to messages during the autotuning
sequence.
®
VLT AQUA Drive Programming Guide
Enabling autotuning 21-09 PID Autotuning puts the relevant
PID controller into PID autotuning mode. The LCP then
directs the user with on-screen instructions.
PID autotuning functions by introducing step changes and
then monitoring the feedback. From the feedback
response, the required values for PID Proportional Gain,
21-21 Ext. 1 Proportional Gain for EXT CL 1, 21-41 Ext. 2
Proportional Gain for EXT CL 2 and 21-61 Ext. 3 Proportional
Gain for EXT CL 3 and Integral Time, 21-22 Ext. 1 Integral
Time for EXT CL 1, 21-42 Ext. 2 Integral Time for EXT CL 2
and 21-62 Ext. 3 Integral Time for EXT CL 3 are calculated.
PID Differentiation Time, 21-23 Ext. 1 Differentation Time for
EXT CL 1, 21-43 Ext. 2 Differentation Time for EXT CL 2 and
21-63 Ext. 3 Differentation Time for EXT CL 3 are set to
value 0 (zero). Normal/Inverse, 21-20 Ext. 1 Normal/Inverse
Control for EXT CL 1, 21-40 Ext. 2 Normal/Inverse Control for
EXT CL 2 and 21-60 Ext. 3 Normal/Inverse Control for EXT CL
3 are determined during the tuning process.
These calculated values are displayed on the LCP, and the
user can decide whether to accept or reject them. Once
accepted, the values are written to the relevant parameters
and PID autotuning mode is disabled in 21-09 PID
Autotuning. Depending on the system being controlled the
time required to carry out PID autotuning could be several
minutes.
Excessive feedback sensor noise should be removed using
the input filter (parameter groups 5-5*, 6-**, and 26-**,
Terminal 53/54 Filter Time Constant/Pulse Filter Time
Constant #29/33) before activating PID autotuning.
[0] Auto
[1] Fast Pressure
[2] Slow Pressure
[3] Fast Temperature
[4] Slow Temperature
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MG20O622 - VLT is a registered Danfoss trademark
21-00 Closed-loop Type
Option: Function:
This parameter defines the application
response. The default mode should be
sufficient for most applications. If the
relative application speed is known, it can
be selected here. This will decrease the
time needed for carrying out PID
autotuning. The setting has no impact on
the value of the tuned parameters and is
used only for the PID autotuning
sequence.
3 3
3-115