Anna University, Regulation 2017, EEE, IC8451-CONTROL SYSTEMS

1. IC 8451&CONTROL SYSTEMS
Department of Electrical and Electronics Engineering
Approved by AICTE | Affiliated to Anna University | Accredited by NAAC | Accredited NBA | Recognized by UGC under 2(f) and 12(B)
Chennai Main Road, Kumbakonam- 612 501.
ARASU ENGINEERING COLLEGE
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2. ARASU
ENGINEERING
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IC 8451&CONTROL SYSTEMS
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Prepared by
Mrs.K.KALPANA.,M.E.,(Ph.D.).,
Department of Electrical and Electronics
Engineering

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 EXAMPLE PROBLEM 2
 Using block diagram reduction technique find closed loop transfer
function of the system whose block diagram is shown in fig
 Step 1: Moving the branch point before the block

4.  Step 2: Combining the blocks in cascade and eliminating parallel blocks
 Step 3:Moving summing point before the block
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5.  Step 4: Interchanging summing points and modifying branch points
 Step 5: Eliminating the feedback path and combining blocks in cascade
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6.  Step 6:Eliminating the feedback path
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Step 7: Eliminating the feedback path

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 EXAMPLE PROBLEM 3
 Deterrmine the transfer function of the given block diagram

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• Case 1:To find C1/R1In this case set R2 =0 and consider only one output C1.
Hence we can remove the summing point which adds R2 and need not
consider G6, since G6 is on the open path.
 Step 1:Eliminating the feedback path

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Step2:Combining the blocks in cascade and splitting the summing
point

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Step 3:Eliminating the feedback path

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Step 4:Combining the blocks in cascade
Step 5: Eliminating the feedback path

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Step 6:Combining the blocks in cascade

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Case 2: To find C2 / R1 In this case set R2=0 and consider only one output C2.
Hence we can remove the summing point which adds R2 and need not consider
(G3, since G3 is on the open path.
Step1:Eliminate the feedback path

15.  Step2:Combining the blocks in cascade and splitting the summing points
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16.  Step 3:Eliminate the feedback path
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17.  Step 4:Combining blocks in cascade.
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18.  Step 5:Eliminating the feedback path
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19.  Step 6:Combining the cascaded blocks
 Result
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20.  HOME WORK PROBLEM
 Obtain the closed loop transfer function of the given block diagram
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