DIGITAL CONTROL SYSTEMS JNTU previous years question papers

DIGITAL CONTROL SYSTEMS JNTU previous years question papers

 Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

1. (a) With help of schematic diagram explain the principal operation of digital to analog conversion.
(b) Explain the conditions to be satisfied for reconstruction of sampled signal into continuous signal.
(c) Explain zero order hold device. [5+5+6]

2. (a) Given the function f(k) = (0.1)kus(k)++0.5k(0.1)kus(k). Find the z-transform of f(k), F(z).
(b) Find the inverse z-transform of the following functions:
i. F(z) = 10z
z2
-1 and
ii. F(z) = 1
z(z-0.2) [8+8]

3. (a) Explain the procedure for obtaining the pulse transfer function of a closed loop transfer function.
(b) Find Y(z) /R(z) for the following sample-data closed - loop systems shown in Figure 3. [6+10]

4. Consider the closed - loop transfer function of the system is given by
C(z)
R(z) = 0.4986(z+0.7453)
z2
-1.262z+0.5235
Draw the pole - zero configurations of the given system. Also find the maximum overshoot and peak time. [16]

5. Consider the digital control system whose transfer function is given by
GH(z) = 0.0952Kz
(z-1)(z-0.905) . Draw the Nyquist plot and determine its stability. [16]

6. A block diagram of a digital control system is shown in Figure 6. Design a compensator D(z) to meet the following specifications:
(a) Velocity error constant, Kv  4 Sec.,
(b) Phase margin  400 and
(c) band width =1.5 rad./sec.

7. Find state model for the following difference equation. Also find its state transition matrix.
y(k+2) + 3y(k+1) + 2y(k) = 5u(k+1) + 3u(k). [16]

8. (a) Derive the necessary condition for the digital control system
X(k + 1) = AX(k) + Bu(k)
Y(k) = CX (k) to be Controllable.
(b) Examine whether the discrete data system
X(k + 1) = AX(k) + BU(k)
Y(k) = CX(k) where A = 1 -2
1 -1  , B = 1 0
0 -1  , C = 1 0
0 1  is
i. State controllable and
ii. Observable. [10+6]

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