This document discusses block diagram reduction techniques and signal flow graphs. It defines a block diagram as a pictorial representation of the functions and signal flows in a control system. Block diagram reduction techniques can be used to simplify block diagrams and find closed loop transfer functions. Signal flow graphs further simplify block diagrams by removing blocks and using branches and nodes instead, with transfer functions called transmittances. Examples are given of representing equations as block diagrams and signal flow graphs. Problems are presented and solved as examples of using these techniques.

1. Block Diagram Reduction Techniques
& Signal Flow Graph
Presented by
Mr. C.S.Satheesh, M.E.,
Assistant Professor, Department of EEE,
Muthayammal Engineering College (Autonomous),
Namakkal (Dt), Rasipuram – 637408
MUTHAYAMMAL ENGINEERING COLLEGE
(An Autonomous Institution)
(Approved by AICTE, New Delhi, Accredited by NAAC, NBA & Affiliated to Anna University),
Rasipuram - 637 408, Namakkal Dist., Tamil Nadu, India.

3. Block diagram
➢ A control system may consist of a number of
components. A block diagram of a system is a
pictorial representation of the functions performed
by each component and of the flow of signals.
➢ The elements of a block diagram are block, branch
point and summing point.

4. Block
In a block diagram all system variables are linked
to each other through functional blocks.
The functional block or simply block is a symbol for
the mathematical operation on the input signal to the
block that produces the output.

6. Block diagram reduction

11. PROBLEM

12. Solution

14. Problem 2:
Using block diagram reduction technique find closed
loop transfer function of the system whose block
diagram is shown in fig

15. solution

19. Result

20. Signal flow graph
➢Signal flow graph of control system is further simplification
of block diagram of control system.
➢Here, the blocks of transfer function, summing symbols and
take off points are eliminated by branches and nodes.
➢The transfer function is referred as transmittance in signal flow
graph.
➢Let us take an example of equation
y = Kx.
➢This equation can be represented with block diagram as below

21. ➢The same equation can be represented by signal flow graph,
➢where x is input variable node, y is output variable node and a is
the transmittance of the branch connecting directly these two
nodes.

24. Problem 1

25. Solution

30. Problem 2

31. Solution

32. 2.Individual loop gain

33. 3.

35. References :
➢ A.Nagoorkani, Control Systems,
RBA Publications.
4/5/2021 35

36. Thank You
36