What is Proportional Integral Derivative Control (PID)?


PID - Proportional Integral Derivative Controller

The PID function uses system feedback to continuously control a dynamic process.

The purpose of PID control is to keep a process running as close as possible to a desired set point.

PID Means - Proportional + Integral + Derivative Control

CV = CV § + CV (I) + CV (D)

Proportional Control

Proportional Band - A band around SP is defined in percents of PV range.

Proportional error is 100% on the border of PB.

Proportional error is 0% at SP.

P-Control output CV§ value that is in - Direct linear proportion to the size of error value.

Advantages of Proportional Control-
Easy to implement

Disadvantages of Proportional Control-
Never reach setpoint.

Integral Control

Compensate for the proportional control shortcomings.

The integral time set is the ideal amount of time for the process value to reach setpoint.

Derivative Action

Derivative Action responds to the rate and direction of change in the error.