proportional controllers, proportional integral controllers and proportional derivative controllers and proportional integral derivative controllers used in the various fields in the control systems.

1. Control systems
Submitted by
PRADEEP D
pradeepdhayanandan@gmail.com

2. Controllers :
A controllers is a control system that manages, commands, directs, or regulates the
behavior of other devices or systems using control loops. It can range from a single
home heating controller using a thermostat controlling a domestic boiler to large
Industrial control systems which are used for controlling processes or machines.
Type of Controllers :
1. Proportional Controller (P)
2. Proportional Derivative Controller (PD)
3. Proportional Integral Controller (PI)
4. Proportional Integral Derivative Controller (PID)
2

3. Proportional Integral (PI) Controller:
 A proportional integral controller is a feedback control loop that calculates an error
signal by taking the difference between the output of a system.
 As the name suggests in integral controllers the output (also called the actuating
signal) is directly proportional to the integral of the error signal.
 Integral Controllers used alongside with proportional controllers are called PI
controllers.
PI controller equation:
 Just like PD controller it also has a parallel connection of P and I controllers.
3

4. Proportional Derivative (PD) Controller:
 This kind of action gives an output which is proportional to the derivative or the rate of
change of the error.
 Derivative control is not used separately (without proportional (P) and integral (I) control) in
a closed-loop system because if the error is constant and non-zero, then the output of
the derivative controller is zero. So it won't work.
 Derivative control is usually found in combination with proportional control,
to form so called P+D.
4

5. Proportional-Integral-Derivative (PID) Controller:
 PID controller involves all the three controllers P, PD and PI connected in parallel.
 The PID instruction is an output instruction that controls physical properties such as
temperature, pressure, liquid level or flow rate using process loops.
 PID controller involves the parallel combination of these 3 controllers and the output
equation is proportional to the derivative as well as integral of the error signal.
5

6. The Characteristics of P, I, and D controllers
 A proportional controller (Kp) will have the effect of reducing the rise time and will
reduce, but never eliminate, the steady-state error.
 An integral control (Ki) will have the effect of eliminating the steady-state error, but it may
make the transient response worse.
 A derivative control (Kd) will have the effect of increasing the stability of the system,
reducing the overshoot, and improving the transient response.
All design specifications can be reached with the PID controller and 100%
desired conditions can be achieved .
6

7. Thank You