B B5811 Pages: 2

Reg No.: Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FIFTH SEMESTER B.TECH DEGREE EXAMINATION, APRIL 2018
Course Code: EE303
Course Name: LINEAR CONTROL SYSTEMS

Max. Marks: 100 Duration: 3 Hours
(Graph sheets and semi-log graph sheets will be provided)
PART A
Answer all questions, each carries 5 marks Marks
1 Give a comparison between open loop and closed loop control systems. Give an (5)
example for each.
2 Explain the working of an AC Tachogenerator with a schematic diagram. (5)
3 For a closed loop system with G(s) = 1/(st+5) and H(s) = 5, calculate the (5)
generalized error coefficients.
4 What is a root locus? What are the information obtained from a root locus? (5)
5 Derive an expression for resonant frequency and resonant peak of a second order (5)
system.
6 Explain Gain margin and Phase margin. (5)
7 State and explain Nyquist stability criterion. (5)
8 Write notes on the following: (5)

1) Non-minimum phase systems _ ii) Transportation lag.
PART B
Answer any two full questions, each carries 10 marks
9 Derive the transfer function of an armature-controlled de motor driving a load (10)
consisting of inertia and friction. Also draw the block diagram.
10 a) Sketch the unit step response of an under damped second order system and mark (3)
various time domain specifications.
b) Obtain the closed loop transfer function C(s)/R(s) using Mason’s gain formula (7)
fora system whose signal flow graph is shown in Fig.1.

Fig. 1
11 ஐ Derive an expression for peak time and settling time of an under damped second (7)

order system.
b) A unity feedback control system is characterized by an open loop transfer (3)
function

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