Danfoss VLT AQUA FC 200 Series Programming Manual page 166

2 Parameter Description
NB!
The setpoint reference entered here is added to any
other references that are enabled (see par. group
3-1*).
2
20-23 Setpoint 3
Range:
0.000* [Ref - Ref
MIN
20-12)]
2.17.4 20-7* PID autotuning
The frequency converter PID Closed Loop controller (parameters 20-**, FC Closed Loop) can be auto-tuned, simplifying and saving time during com-
missioning, whilst ensuring accurate PID control adjustment. To use auto-tuning it is necessary for the frequency converter to be configured for closed
Configuration Mode
loop in par.1-00
A Graphical Local Control Panel (LCP) must be used in order to react on messages during the auto-tuning sequence.
Enabling par.20-79 PID Autotuning
The fan/pump is started by pressing [Auto On] button on the LCP and applying a start signal. The speed is adjusted manually by pressing the [
▼
[ ] navigation keys on the LCP to a level where the feedback is around the system set-point.
NB!
It is not possible to run the motor at maximum or minimum speed, when manually adjusting the motor speed due to the need of giving
the motor a step in the speed during auto-tuning.
PID auto-tuning functions by introducing step changes whilst operating at a steady state and then monitoring the feedback. From the feedback response,
the required values for par.20-93
value 0 (zero). par. 20-81
These calculated values are presented 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 auto-tuning mode is disabled in par.20-79
carry out auto-tuning could be several minutes.
It is advised to set the ramp times in par.3-41
Ramp 2 Ramp Down Time
3-52
the auto-tuned parameters will typically result in very slow control. Excessive feedback sensor noise should be removed using the input filter (parameter
groups 6-**, 5-5* and 26-**, Terminal 53/54 Filter Time Constant/Pulse Filter Time Constant #29/33) before activating PID autotuning. In order to obtain
the most accurate controller parameters, it is advised to carry out PID autotuning, when the application is running in typical operation, i.e. with a typical
load.
166
Function:
UNIT (from par. Setpoint 3 is used in Closed Loop Mode to enter a setpoint reference that may be used by the
MAX
frequency converter's PID Controller. See the description of par. 20-20 Feedback Function.
.
, puts the frequency converter into auto-tuning mode. The LCP then directs the user with on-screen instructions.
PID Proportional Gain and par.20-94
PID Normal/ Inverse Control is determined during tuning process.
Ramp 1 Ramp Up Time
according to the load inertia before carrying out PID autotuning. If PID autotuning is carried out with slow ramp times,
MG.20.O4.02 - VLT
VLT
NB!
If the min and max references are altered, a new PI - Autotune may be needed.
NB!
The setpoint reference entered here is added to any other references that are
enabled (see par. group 3-1*).
PID Integral Time are calculated. par. 20-95
PID Autotuning . Depending on the system being controlled the time required to
, par.3-42 Ramp 1 Ramp Down Time
®
is a registered Danfoss trademark
®
AQUA Drive Programming Guide
PID Differentiation Time is set to
or par.3-51 Ramp 2 Ramp Up Time and par.
▲
] or