Pid Control - Kruger Ecowatt K320 Series Operation Manual

Ecowatt Drive K320 series
®
Function code
P10.33
P10.34
P10.35
P17.27

5.5.15 PID control

PID control, a common mode for process control, is mainly used to adjust the VFD output
frequency or output voltage through performing scale-division, integral and differential
operations on the difference between feedback signal of controlled variables and signal of the
target, thus forming a negative feedback system to keep the controlled variables above the
target. It is suitable for flow control, pressure control, temperature control, etc. Diagram of
basic principles for output frequency regulation is shown in the figure below.
Pre-set PID reference of
keypad
P09.01 Keypad
(PID reference source)
AI1
0
AI2
1
AI3
2
3
HDIA
4
Multi-step
speed
5
6
MODBUS
7
PROFIBUS\CANopen
8
Ethernet
9
HDIB
EtherCat/Profinet 10
11
PLC card
Introduction to the working principles and control methods for PID control
Proportional control (Kp): When the feedback is different from the reference, the output will be
proportional to the difference. If such a difference is constant, the regulating variable will also
be constant. Proportional control can respond to feedback changes rapidly, however, it cannot
eliminate the difference by itself. A larger the proportional gain indicates a faster regulating
speed, but a too large gain will result in oscillation. To solve this problem, set the integral time
to a large value and the differential time to 0, run the system only with proportional control,
and then change the reference to observe the difference (that is, static difference) between the
Name
Running time of step 15
ACC/DEC time of steps 0–7
of simple PLC
ACC/DEC time of steps
8–15 of simple PLC
Simple PLC and present
stage number of multi-step
speed
P09.00
PID reference
value
P17.23
+
Reference-
feedback<P09.08？
-
P09.08 (Limit of PID control
P09.02
(PID feedback source)
P17.24
PID feedback
value
0.0–6553.5s (min)
0x0000–0XFFFF
0x0000–0XFFFF
Displays the present stage of
the simple PLC function.
Terminal function 25
PID control pause
Y
Valid
Keep current frequency
N Invalid
deviation)
Kp P09.04 (proportional gain)
AI1
Ti P09.05 (integral time)
0
AI2
Td P09.06 (differential time)
1
AI3
2
3
HDIA
4
MODBUS
5
6
PROFIBUS\CANopen
7
Ethernet
8 HDIB
EtherCat/Profinet
9
PLC card
10
-112-
Basic operation guidelines
Description
adjustment
P09.09
（upper limit value of PID
output）
(PID output characteristics)
P09.10
(lower limit value of PID
output)
Default
0.0s
0000
0000
0
PID stops
Set frequency
P17.00
0
1
PID output
P09.03