B5: Pid Control - YASKAWA FSDrive-MV1000 Parameter Manual

2.2 b: Application

◆ b5: PID Control

The PID controller matches the feedback value (detected value) to the target value. Proportional (P), Integral (I), and D
(Derivative) combination control is also available for machinery applications in which a loss time occurs.
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.
■ I Control
The output of I control is the integral of the deviation. It matches the feedback value to the target value. When the target
value changes rapidly, this control is lost.
D Control
■
D control predicts the deviation signal by multiplying its derivative (slope of the deviation) by a time constant, then adds
this value to the PID input. This way the D portion of a PID controller provides a braking action on the controller
response and can reduce the tendency to oscillate and overshoot.
Be aware that D control tends to amplify noise on the deviation signal, which can result in control instability. D control
should therefore only be used when necessary.
PID Operation
■
To better demonstrate how PID works, the diagram below shows how the PID output changes when the PID input
(deviation) jumps from 0 to a constant level.
Using PID Control
■
Applications for PID control are listed in the table below.
Application
Machinery speed is fed back and adjusted to meet the target value.
Speed Control Synchronous control is performed using speed data from other machinery as the target
value
Pressure Maintains constant pressure using pressure feedback.
Fluid Control Keeps flow at a constant level by feeding back flow data.
Temperature
Maintains a constant temperature by controlling a fan with a thermostat.
Control
110
PID input
D control
PID Output
Description
Time
PID output
I control
common_TMonly
P control
Time
Tachometer
Pressure sensor
Flow rate sensor
Thermocoupler, Thermistor
YASKAWA ELECTRIC EZZ010930 FSDrive-MV1000 Parameter Guide
Sensors Used