A-32
Appendix 8 PID Function
1.
Function
The PID (Proportional, Integral, Differential) control functions can apply to controlling of the
air (water) amount of a fan pump, etc., as well as controlling of pressure within a fixed value.
Set the reference signal according to the frequency setting method or the internal level.
Set the feed-back signal according to the analog voltage input (0 to 5V or 0 to 10V) or analog
current input (4 to 20 mA).
[Wiring Sketch]
0 to 10 V
0 to 5 V
4 to 20 mA
or Internal level
0 to 200%
Reference
J300
Feed-back Signal (0 to 5 V, 0 to 10 V, 4 to 20 mA)
Load (Fan Pump, etc.)
Transducer
Sensor
2.
PID Gain
If the response is not stabilized in a PID control operation, adjust the gains as follows according
to the symptom of the inverter.
•
The change of controlled variable is slow even when the target value is changed.
— Increase the P gain.
•
The change of controlled variable is fast, but not stable.
— Decrease the P gain.
•
It is difficult to make the target value match with the controlled variable.
— Decrease the I gain.
•
Both the target value an the controlled variable are not stable. They match after oscillation.
— Increase the I gain.
•
The response is slow even 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.
