P : Proportional Control - Hitachi L100 300 User Manual

SJ100/L100 series inverters have integrated PID control, which is indicated by the dotted line in Fig. 2-1.
You can use PID control by setting a target value and providing a feedback signal.
The example in Fig. 2-2 shows a connection diagram for ventilation flow control in a fan application.
Target
4 bit of digital
input signal
Motor

(1) P : Proportional Control

This controls the output frequency so that output frequency and deviation have a proportional relation.
The coefficient of deviation and output frequency (expressed in %) is called Proportional Gain (K
parameter can be set under function [A71].
Fig. 2-3 shows the relationship between deviation and output frequency. If you set a high value of K
the response of the system to a rapid change in deviation is fast. However, if K
can become unstable.
Max. frequency <--- 100
Fig. 2-3 Relation between deviation and output frequency of SJ100/L100
100% of output frequency of above figure is equivalent to maximum output frequency.
K can be chosen between 0.2 and 5.0 in function [A71].
p
SJ100/
Feedback
(DC0-10V, 4-20mA)
L100
Fan
Fig. 2-2 Wiring example for flow control application
K =2
p
Output
75
frequency
50
(%)
25
0
SJ100/L100 / PID / 4
Flow volume sensor
K
p
K
p
Kp=0.5
Kp=0.25
25 50 75 100
Deviation(%)
Transducer
is too high, the system
p
=1
=0.75
0 2 . Kp 5 0
). This
p
,
p
.