Process Controller Optimization - Danfoss VLT Midi Drive FC 280 Design Manual

Product Overview
Function
2 2
Set terminal 53 low voltage.
Set terminal 53 high voltage.
Set terminal 54 low feedback value.
Set terminal 54 high feedback value.
Set feedback source.
6) Basic PID settings:
Process PID normal/inverse.
Process PID anti wind-up.
Process PID start speed.
Save parameters to LCP.
Table 2.10 Example of Process PID Control Set-up

2.5.5 Process Controller Optimization

After configuring the basic settings as described in
chapter 2.5.5 Programming Order, optimize the proportional
gain, the integration time, and the differentiation time
(parameter 7-33 Process PID Proportional Gain,
parameter 7-34 Process PID Integral Time, and
parameter 7-35 Process PID Differentiation Time). In most
processes, complete the following procedure:
1. Start the motor.
2. Set parameter 7-33 Process PID Proportional Gain
to 0.3 and increase it until the feedback signal
again begins to vary continuously. Reduce the
value until the feedback signal has stabilized.
Lower the proportional gain by 40–60%.
3. Set parameter 7-34 Process PID Integral Time to 20
s and reduce the value until the feedback signal
again begins to vary continuously. Increase the
34
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VLT Midi Drive FC 280
Parameter Setting
number
Parameter 6-10 0 V
Terminal 53 10 V
-5 °C (23 °F)
Low Voltage
35 °C (95 °F)
Parameter 6-11
Terminal 53 [2] Analog input 54
High Voltage
Parameter 6-24
Terminal 54
Low Ref./Feedb.
Value
Parameter 6-25
Terminal 54
High Ref./
Feedb. Value
Parameter 7-20
Process CL
Feedback 1
Resource
Parameter 7-30 [0] Normal
Process PID
Normal/
Inverse Control
Parameter 7-31 [1] On
Process PID
Anti Windup
Parameter 7-32 300 RPM
Process PID
Start Speed
Parameter 0-50 [1] All to LCP
LCP Copy
4.
NOTICE
If necessary, start/stop can be activated several times to
provoke a variation of the feedback signal.
Danfoss A/S © 03/2016 All rights reserved.
integration time until the feedback signal
stabilizes, followed by an increase of 15–50%.
Only use parameter 7-35 Process PID Differentiation
Time for fast-acting systems (differentiation time).
The typical value is 4 times the set integration
time. Use the differentiator when the setting of
the proportional gain and the integration time
has been fully optimized. Make sure that the
lowpass filter dampens the oscillations on the
feedback signal sufficiently.
MG07B102