## March 9, 2010

### EE1212 CONTROL SYSTEMS

2009 Tamil Nadu State Anna University B.E Electrical and Electronics CONTROL SYSTEMS Question paper ANNA UNIVERSITY – COIMBATORE
B.E.\B.TECH.DEGREE-EXAMINATION-DECEMBER 2008
FIFTH SEMESTER-ELECTRICAL &ELECTRONICS ENGG.
EE1212 CONTROL SYSTEMS

PART A-(2*20=40)
1. Define transfer function.
2. Name two types of electrical analogous for mechanical system.
3. What is a signal flow graph.
4. What is servomechanism.
5. List the time domain specifications.
6. Define peak overshoot.
7. A unity negative feedback system has Kp=5. What steady state error can be expected for inputs of 6u(t) and 6t u(t).
8. Why derivative controllers is not used in control system.
9. Define gain margin.
10. What are the main advantages of Bode plot.
11. What are M circles.
12. List out the different frequency domain specifications.
13. State Nyquist stability criterion.
14. What are the main sequences of root locus.
15. What is limitedly stable system.
16. What is centroid. How the centroid is calculated.
17. What is a compensator.
18. When is the lag-lead compensator required.
19. Write the procedure for designing the lag compensator.

PART B-(5*12=60)
21. Write the differential equations governing the mechanical rotational system shown in fig. Obtain the transfer function of the system.

22. Explain the construction and working principle of AC servomotor.
23. A) Write the standard test signals used in the control system. (4)
B) Obtain the unit ramp and unit impulse response of a first order system. (8)
24. Draw the Bode plot for the open loop transfer function G(s)= K/s(s+1)(0.1s+1). Determine phase margin and gain margin.
(i) find the value of k to give a gain margin 10db.
(ii) (ii) find the value of K to give gain margin 30db.
(iii) (iii) find the value of K to give a phase margin of 24o
(iv) (iv) the marginal value of k for stability.
25. A) Construct the routh array system for the equation: s4+8s3+16s+5=0 and comment on the stability of the system. (4)
B) Consider the closed loop transfer feedback system shown in fig. Determine the range of k for which the system is stable. (8)

26. Sketch the root locus plot for 0<8. Given G(s)H(s) = k(s2-4s+20)
(s+2)(s+4)
Find the following:
a) the gain k at the j?-axis crossing,
(b) the gain at that point where the locus crosses the 0.45 damping atio line.
27. The closed loop transfer function of certain unity feedback control system is given by G(s)=K/s(s+4)(s+80). It is desired to have the phase margin to be at least 330 and the velocity error constant Kv=30sec-1. Design a phase lag series compensator.
28. Consider the unity feed back system whose open loop transfer function is G(s)=K/s(s+3)(s+6). Design a lag-lead compensator to meet the following specifications.
(i) velocity error constant, Kv=80,
(ii) (ii) phase margin ?=35o.

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