Danfoss VLT AutomationDrive FC 302 - Page 183

P 20-81
PID Normal/Inverse
Control
PID
Ref.
Handling
Feedback
Handling
Scale to
speed
P 4-10
Motor speed
direction
To motor
control
(Illustra-
tion)
(Illustra-
tion)
130BA359.12

100%
0%
-100%
100%
*[-1]
_
+
Illustration 11.7 Block Diagram of Closed-loop Controller
Programmable features
While the default values for the drive in closed loop often provide satisfactory performance, system control can often be
optimized by tuning the PID parameters. Auto tuning is provided for this optimization.
•
Inverse regulation - motor speed increases when a feedback signal is high.
•
Start-up frequency - lets the system quickly reach an operating status before the PID controller takes over.
•
Built-in lowpass lter - reduces feedback signal noise.
11.2.7 Control Processing
See Active/Inactive Parameters in Dierent Drive Control Modes in the programming guide for an overview of which control
conguration is available for your application, depending on selection of AC motor or PM non-salient motor.
11.2.7.1
Control Structure in VVC
+
+
_
+
_


Cong. mode
Ref.
Process
P 1-00
High
+f max.
Low
-f max.
P 4-11
Motor speed
low limit (RPM)
P 4-12
Motor speed
low limit (Hz)
P 4-13
Motor speed
high limit (RPM)
P 4-14
Motor speed
high limit (Hz)
Motor
controller
Ramp
Speed
PID
P 7-20 Process feedback
1 source
P 7-22 Process feedback
2 source
P 7-00 Speed PID
feedback source
P 1-00
Cong. mode
P 4-19
Max. output freq.
-f max.
Motor
controller
P 4-19
Max. output freq.
+f max.
P 3-**
P 7-0*
130BA055.10
Illustration 11.8 Control Structure in VVC
+
Open Loop and Closed-loop Congurations
In Illustration 11.8, the resulting reference from the reference handling system is received and fed through the ramp
limitation and speed limitation before being sent to the motor control. The output of the motor control is then limited by
the maximum frequency limit.
Basic Operating Principles ... Design Guide
MG38C202 Danfoss A/S © 01/2018 All rights reserved. 181
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