Delta CFP2000 Series, User Manual

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Chapter 12 Description of Parameter Settings
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CFP2000
12.1-08-3
the error is small. It gradually increases the controller output to eliminate the error until it is
zero. This stabilizes the system without a steady-state error by using proportional gain
control and integral time control.
Adjustment: The integral time (I) accumulates from the time difference, if the vibration
cycle is longer than the setting for integral time, the integration enhances.
Increase the integral time (I) to reduce the vibration.
Increase: Reduce the overshoot, excessive adjustment causes worse transient response.
Decrease: Faster transient response, but the transient time will be longer, and takes more
time to achieve the steady state. Excessive adjustment causes larger overshoot.
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Differential control (D):
The controller output is proportional to the differential of the controller input. During
elimination of the error, oscillation or instability may occur. Use the differential control to
suppress these effects by acting before the error. That is, when the error is near zero, the
differential control should be zero. Use proportional gain (P) and differential control (D) to
improve the system state during PID adjustment.
Adjustment: When the vibration cycle is shorter and continuous, it means that the
differential time setting is too large, and causes excessive output. Decrease
the setting of D gain to reduce the vibration. If the D gain is set to 0, adjust the
PID control again.
Using PID control in a constant pressure pump feedback application:
Set the application’s constant pressure value (bar) to be the set point of PID control. The pressure
sensor sends the actual value as the PID feedback value. After comparing the PID set point and
PID feedback, an error displays. The PID controller calculates the output by using proportional
gain (P), integral time (I) and differential time (D) to control the pump. It controls the drive to use a
different pump speed and achieves constant pressure control by using a 4–20 mA signal
corresponding to 0–10 bar as feedback to the drive.