B5: Pid Control - YASKAWA AC Drive-A1000 Technical Manual

n Timer Function Operation
The timer function switches on when the timer function input closes for longer than the value set to b4-01. The timer function
switches off when the timer function input is open for longer than the value set to b4-02. The following diagram illustrates
the timer function operation:
Multi-function Contact
Input: Timer Function
Multi-function Contact
Output: Timer Function
u

b5: PID Control

The drive has a built-in Proportional + Integral + Derivative (PID) controller that uses the difference between the target value
and the feedback value to adjust the drive output frequency to minimize deviation and provide accurate closed loop control
of system variables such as pressure or temperature.
n P Control
The output of P control is the product of the deviation and the P gain so that it follows the deviation directly and linearly. With
P control, only an offset between the target and feedback remains.
n I Control
The output of I control is the integral of the deviation. It minimizes the offset between target and feedback value that typically
remains when pure P control is used. The integral time (I time) constant determines how fast the offset is eliminated.
n D Control
D control predicts the deviation signal by multiplying its derivative (slope of the deviation) with a time constant, then adds
this value to the PID input. This way the D portion of a PID controller provides a braking action to the controller response and
can reduce the tendency to oscillate and overshoot.
D control tends to amplify noise on the deviation signal, which can result in control instability. Only use D control when
absolutely necessary.
n PID Operation
To better demonstrate PID functionality, the diagram below illustrates how the PID output changes when the PID input
(deviation) jumps from 0 to a constant level.
YASKAWA ELECTRIC SIEP C710616 31B YASKAWA AC Drive – A1000 Technical Manual
ON
ON
b4-01 b4-02
Figure 5.20 Timer Operation
PID input
D control
PID Output
Figure 5.21 PID Operation
ON
ON
b4-01 b4-02
Time
PID output
I control
P control
Time
5.2 b: Application
On (Closed)
Off (Open)
On (Closed)
Off (Open)
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