III B.Tech I Semester Supplementary Examinations, May - 2017

CONTROL SYSTEMS

(Electrical and Electronics Engineering)

Time: 3 hours Max. Marks: 70

Note: 1. Question Paper consists of two parts (Part-A and Part-B)

2. Answer ALL the question in Part-A

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3. Answer any THREE Questions from Part-B

PART-A

1. a) Define transfer function. [2M]

b) List the advantages of closed loop control system. [2M]

c) Define steady state error. [2M]

d) What is meant by corner frequency? [2M]

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e) Define gain margin. [2M]

f) What are the effects of adding a pole to the system? [2M]

g) Define state transition matrix. [2M]

PART-B

2. a) Explain the open loop and closed loop control systems with suitable examples. [8M]

b) Determine the transfer function C(s)/R(s) for the system shown in below figure. [8M]

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b) The open loop transfer function of a unity feedback control system is given by G(s) = K / s(s+5)(s+2). Find the range of K so that the steady state error for unit ramp input is less than 0.1 [8M]

4. a) State and explain the Nyquist stability criterion. [8M]

b) Sketch the Bode plot for the transfer function G(s) = 10 / s(1+0.4s)(1+0.1s). Determine the gain margin and phase margin. Determine the stability of the system. [8M]

5. The characteristic equation of feedback control system is given by s⁴ + 2s³ + (4+K)s² + 9s + k = 0. Using Routh Hurwitz criterion determine the range of k for which the system to be stable. [16M]

6. a) Explain the terms absolute stability and relative stability. [8M]

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b) Explain the procedure for construction of root locus. [8M]

7. a) Define the terms i) State ii) State variable iii) State vector iv) State space [8M]

b) Obtain the state model for the system described by [8M]

d²y/dt² + 5dy/dt + 6y = u

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