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BLOCK DIAGRAM REPRESENTATION
MADE BY - NIRALI MONANIBRANCH - ELECTRONICS & COMMUNICATION
INTRODUCTION
• A Block Diagram is a shorthand pictorialrepresentation of the cause-and-effectrelationship of a system.
• The interior of the rectangle representing theblock usually contains a description of or thename of the element, gain, or the symbol for themathematical operation to be performed on theinput to yield the output.
• The arrows represent the direction of information or signal flow.
dt
dx y
COMPONENTS OF BLOCK DIAGRAM
ADVANTAGES OF BLOCK DIAGRAM
• THE FUNCTIONAL OPERATION OF THE SYSTEM CAN BE OBSERVED FROM BLOCK DIAGRAM
• BLOCK DIAGRAM GIVES THE INFORMATION ABOUT PERFORMANCE OF SYSTEM
• BLOCK DIAGRAM IS USED FOR ANALYSIS & DESIGN OF CONTROL SYSTEM
• IT IS VERY SIMPLE TO CONSTRUST THE BLOCK DIAGRAM FOR BIG & COMPLICATED SYSTEM
DISADVANTAGES OF BLOCK DIAGRAM
• BLOCK DIAGRAM FOR GIVEN SYSTEM ARE NON UNIQUE
• SOURCE OF ENERGY IN THE SYSTEM IS NOT SHOWN IN THE DIAGRAM
• IN THE PROCEDURE OF REDUCTION OF BLOCK DIAGRAM ALGEBRA SOME IMPORTANT FUNCTIONSMAY BE OMITTED . THERE IS NO CHECK FOR IT
• IT DOESN’T GIVE ANY INFORMATION ABOUT PHYSICAL CONSTRUCTION OF THE SYSTEM
Canonical Form of A Feedback Control System
Characteristic Equation
• The control ratio is the closed loop transfer function of the system.
• The denominator of closed loop transfer function determines thecharacteristic equation of the system.
• Which is usually determined as:
)()(
)(
)(
)(
sHsG
sG
sR
sC
1
01 )()( sHsG
RULES OF BLOCK DIAGRAM REDUCTION
Reduction techniques procedure
:1. Combining blocks in cascade or in parallel
1G2G
21GG
1G
2G
21 GG
14
2. Moving a summing point behind a block:
G G
G
:3. Moving a summing point ahead of a block
G G
G
1
15
4. Moving a pickoff point behind a block:
G G
G
1
5. Moving a pickoff point ahead of a block:
G G
G
16
6. Eliminating a feedback loop:
G
H
G
1H
G
G
1
GH
G
1
17
THANK YOU !!!