8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 1/26

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 2/26

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 3/26

 Any Practicalsystem is a

control system

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 4/26

+

+

+

RV

r(t)MV

u(t)CONTROLLERD(s)

PLANTG(s)

SENSOR

H(s)

Error Detector

Actuating

Error

e(t)

CV

c(t)

Feedback

signal

b(t)

Disturbance

N(s)

+-

^

Disturbancesignal

w(t)

Typical Block Diagram model for a Feedback Control System

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 5/26

Proportional control

+

r(t) u(t)

G(s)K

H(s)

c(t)e(t)

-

Control action:- u(t)=Ke(t)Effect on Steady State Response:- Reduces the steady state error 

Effect on Transient Response:- Increases the speed of response.

Limitations and shortcomings:- Saturation, noise and instability .

Hence new contr ol schemes (PI, PD) are conceived .

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 6/26

Proportional and Integral (PI) control

+

r(t) u(t)

K G(s)

H(s)

K /s

c(t)e(t)

-+

+

Control action:- u(t)=Ke(t)+K I  ∫e(t)dt 

U(s)=(K+ K I  /s)E(s) where K I =1/T I  , T I =Integral or reset time

Effect on Steady State Response:- steady state error can be reduced to

 zero exactly.

Effect on Transient Response:-Increases peak overshoot & reduces the

speed of response.

Limitations and shortcomings:- Reduces the stability margin of the

system.

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 7/26

Proportional and Derivative (PD) control

+

r(t) u(t)K G(s)

H(s)

sK 

c(t)e(t)

-+

+

Control action:- u(t)=Ke(t)+K D(de/dt)

U(s)=(K+ sK D )E(s) where K D=K c T D , T D=Derivative or rate time.

Effect on Steady State Response:- Almost no effect .

Effect on Transient Response:-Decreases the peak overshoot by

improving the effective damping of the system.

Limitations and shortcomings:- Amplifies the high frequency noise

signals.

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 8/26

Proportional ,Integral & Derivative (PID) control

Control action:-By proper adjustment of K, K D ,K   the transient and

dynamic responses are properly shaped.

Problems:-Tuning of PID controller is a difficult job.

+

r(t) u(t)G(s)

H(s)

c(t)e(t)

-+

+

+

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 9/26

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 10/26

Let

M = Mass=1kg

b =co-efficient of damping= 10 N.s/m

k = spring constant=20 N/m

MASS,SPRING,DAMPER system-A simple 2nd order system

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 11/26

System without any controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 12/26

Response of the system without any controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 13/26

System with P controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 14/26

Response of the system with P controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 15/26

System with PD controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 16/26

Response of the system with PD controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 17/26

System with PI controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 18/26

Response of the system with PI controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 19/26

System with PID controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 20/26

Response of the system with PID controller

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 21/26

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 22/26

VOLTAGE

SUPPLY

LOAD

r  f  af  a   i L E     

+

-

er   T , 

 LT 

+

-

ar 

ai

ar r 

a L

 fr r 

 f  i

 f  r 

 f  u

 f   L

auaxisquadrature

axisdirect 

armature

 field 

Speed Control system of Separately excited DC motor

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 23/26

BLOCK DIAGRAM MODEL

w+Tm

+wr er

KP D(S) KT/Ra 1/(Js+B)

Kb

Kt

TW

eb

ea

-+ -+

et

Kp=Potentiometer constantKt= Tacho-generator constant

Kb=Back emf constant

KT=Torque constant

Tw=Disturbance torque/ load torque.Tm=Electromagnetic Torque developed by motor.

D(s)=Controller Transfer Function.

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 24/26

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 25/26

ACKNOWLEDGEMENT

•en.wikipedia.org

•www.youtube.com

•‘Modern Control Engineering ‘ by k.Ogata.

•‘Control Systems: Principles and Design’ by Madan Gopal.

•‘PID -controllers, Theory Design and Tuning’ by K Astrom and 

T Hagglund 

•‘Automatic Control Systems’ by B.C Kuo

8/10/2019 Presentation on PID Controller

http://slidepdf.com/reader/full/presentation-on-pid-controller 26/26

!!!!THANK YOU!!!