Appendix 8 Pid Function - Hitachi J300 Series Instruction Manual

Appendix 8 PID Function
1. Function
The PID (hoportional, Integral, Difierential) control furtions can apply to controlling ofthe
air (water) amount ofa fan pump, etc., as well as controlling ofpressure within a fixed value.
Set the reference signal according to the ftequency settirg method or the intemal level.
Set the feed-back signal according to the analog voltage input (0 to 5V or 0 to lov) or analog
current input (4 to 20 mA).
[Wiring Sketch]
Reference
0 t o l 0 V
0 t o 5 V
4 t o 2 0 m A
or Intemal level
0 to 2007o
Feed-back Signal (0 to 5 V, 0 to l0 V, 4 to 20 mA)
PID Gain
If the response is not stabilized in a PID control operation, adjust the gains as follows accord-
ing to the symptom ofthe inverter.
.
The change of controlled variable is slow even when thc target value is changed.
- Incrcase the P grin.
.
The change ofcontrolled variable is fast, but not stable.
Decrease the P gain.
.
It is difficult to make the ta-rget value match with the controlled variable.
- Decrease the I gain.
.
Both the target value an the conffolled va able are not stablc. They match after oscilla
uon,
Increase the I gain.
.
The response is slow cven when the P gain is increased.
-
Increase the D gain.
.
The response is not stabilized due to oscillation even when the P gain is increased.
-
Decrease the D gain.
Sensor
Transducer
,
A-32
Irad (Fan Pump, etc.)