# PTU B.Tech Electrical Engineering 6th Semester May 2019 71149 NON LINEAR AND DIGITAL CONTROL SYSTEMS Question Papers

PTU Punjab Technical University B-Tech May 2019 Question Papers 6th Semester Electrical and Electronics Engineering (EEE)-EE-Electrical Engineering

Roll No.
Total No. of Pages : 02
Total No. of Questions : 09
B.Tech.(EE/Electrical & Electronics/Electronics & Electrical)
(2011 Onwards)
(Electrical Engg. & Industrial Control/Electronic Engg.) (2012 Onwards)
(Sem.?6)
NON-LINEAR AND DIGITAL CONTROL SYSTEMS
Subject Code : BTEE-603
M.Code : 71149
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1.
SECTION-A is COMPULSORY consisting of TEN questions carrying T WO marks
each.
2.
SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3.
SECTION-C contains T HREE questions carrying T EN marks each and students
have to attempt any T WO questions.

SECTION?A
1.

(a) Discuss the advantages of state space approach over transfer function approach.

(b) Explain the term Observability.

(c) What are singular points?

(d) What do you mean by an equilibrium point?

(e) Define limit cycle.

(f) Define describing function.

(g) Explain dead zone with a suitable example.

(h) What are the properties of Lyapunov's function?

(i) What do you mean by zero order hold?

(j) Discuss the limitations of Z transform.
SECTION-B
2.
The transfer function of a control system is given by :
4(s 2)
G(s)

s(s 3)(s 4)

Draw the state diagram and obtain the state equation.

1 | M-71149

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3.
Draw the phase portrait of the following system, using the method of isoclines :

0.5 0
4.
Find out the describing function for Backlash nonlinearity.
5.
An autonomous system is expressed as follows :
x x
1
2
x ?m x ? m x
2
1 2
2 1

Study the stability of the system using Lyapunov's method and considering the
Lyapunov's function as :
2
2
W x x
1
2
6.
Determine the relationship between z and s domains.

SECTION-C
7.
A closed loop control system is shown below :
Sampler with
r(t) +
T = 1s
C(t)
1
ZOH
s+1
e(t)
?
1
s

Fig.1

Determine the output in discrete form when a unit step is applied to the input.
8.
How can you find out Lyapunov's function by Krasovskii's and Variable gradient
methods?
9.
Determine whether the system shown below exhibits self sustained oscillations. If so,
determine the stability, frequency, and amplitude of the oscillation.
+1
C
r +
e
k
?
p(p+1)(p+2)
?1

Fig.2
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