control system (pt)

7/30/2019 Control System (Pt)

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H1

G3

H2

VINAYAKA MISSIONS UNIVERSITY

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

SEMESTER-III

QUESTION BANK

CONTROL SYSTEM (Part Time )

Ordinary graph sheet, semi log sheet, polar graph sheet will be provided

UNIT I

SYSTEMS AND THEIR REPRESENTATION

PART A

1. What is a control system?2. Define transfer function of a system.

3. Define summing point

4. What is feedback control system?5. Distinguish between open loop and closed loop system

6. What is servo motor?

7. What are signal flow graphs?

8. State Masons gain formula.9. What are the two electrical analogies for mechanical systems?

10. State the properties of a signal flow graph.

PART B

1) The block diagram of a closed loop system is shown in the figure using the

block reduction technique determine the closed loop transfer function C(s)/R(s). (12)

R- C

+ + G1 + G2

- -


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2) Convert the block diagram to signal flow graph and determine the transfer

function using masons gain formula. (12)

3) The signal flow graph for a feedback control system is shown in fig. Determine theclosed loop transfer function C(s) /R(s) (12)

G6

R G1 G2 G3 G4G5 C

H1 H2 H3

4) The block diagram of a closed loop system is shown in the figure using the

block reduction technique determine the closed loop transfer function C(s)/R(s). (12)

6 + + C(S)

7 8 9

+ 5

4 -

+

3 -

+

2 -

R(S)1

G1

G4

G2

G3

H1

H1

C(

+

+

--

+

-

R(S)

G1

H2

G2 G

3

H1

G4


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5) Convert the block diagram to signal flow graph and determine the transfer function

using Masons gain formula (12)

C(S)

+

+

--

+

-

R(S) G1

H2

G2 G

3

H1

G4


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UNIT II

TIME RESPONSE

PART A

1. Define damping ratio.

2. How the system is classified depending on the value of damping?3. The closed loop transfer function of second order system is C(s) = 25______

R(s) s2 + 6s + 10

Determine damping ratio.

3. What are the types of test signals?

4. What is steady state error?5. What are generalized error coefficients?

6. Mention the disadvantages of static error constants.

7. Define peak time.8. Define peak overshoot

9. Give the relation between generalized and static error coefficients

10. Write the transfer function of PID controller.

PART B

1. Derive the expression for unit step response of a second order under damped systemG(s) =Wn2/s2+2WnS+Wn

2. (12)

2. Find the unit step response of the second order system whose transfer functionG(S) =9/s2+4s+9. (12)

3. The unity feedback system is characterized by an open loop transfer function

G(s)=K/s(s+10).Determine the gain K, so that system will have a damping ratio of0.5 for this value of K. Determine settling time ,peak overshoot and time to peak

overshoot for a unit step input. (12)

4. Derive the expressions for following time domain specifications to the second order

under damped system.

(i). Peak time (6)(ii). Peak Overshoot (6)

5. Explain in details about generalized error coefficients. (12)


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UNIT III

FREQUENCY RESPONSE

PART A

1. What is gain cross-over frequency?

2. Define phase margin of a closed loop system3. What is a Nichols chart?4. What are the frequency domain specifications?

5. Define gain margin of a closed loop system.

6. Define bode plot.

7. What is cut off rate?8. Define corner frequency?

9. What is phase cross over frequency?

10. State the advantages of Nichols chart.

PART B

1. For a unity feedback system

G(s)=10/s(s+1)(s+4) (12)Obtain the gain margin and phase margin by bode plot.

2. Consider a unity feed back system having open loop transfer functionG(s)=1/s2(1+s)(1+2s) (12)

sketch polar plot and determine gain and phase margin.

3. The open loop transfer function of a unity feedback system is given byG(s)=1/s(1+s)2.

Sketch the polar plot and determine the gain and phase margin. (12)

4. Explain the constant M and constant N-circles (12)

5. Consider a unity feed back system having open loop transfer functionG(S) = 75(1+0.2s)/s(s+5). Sketch bode plot and determine phase margin and gain

margin. (12)


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UNIT-IV

STABILITY OF CONTROL SYSTEM

PART-A

1) Define BIBO stability.

2) What are asymptotes? How will you find the angle of asymptotes?3) What is centroid? How the centroid is calculated?4) What is the necessary condition for stability?

5) What is routh stability criterion?

6) What is Nyquist stability criterion?

7) How the roots of the characteristic equation are related to stability.8) What is root locus?

9) What is breakaway and breakin point?

10) Define gain margin and phase margin.

PART-B

1) Sketch the root locus for the unity feed back system whose open loop transfer

function is

G(s)=K / s(s2+6s+10) (12)

2) Using Routh criterion, determine the stability of the system represented by the

characteristics equation, s7+9s6+24s5+24s4+24s3+24s2+23s+15 = 0. Comment on

the location of the roots of the roots of characteristics equation. (12)

3) Construct Routh array and determine the stability of the system represented by the

characteristics equation s5+s4+2s3+2s2+3s+5 = 0. Comment on the location of the

roots of characteristics equation. (12)

4) Draw the Nyquist plot for the system whose open loop transfer function is

G(s) H(s) = K/s(s+2) (s+10). (12)

Determine the range of K for which closed loop system is stable.

5) Construct the Nyquist plot for a system whose open loop transfer function is

given by

G(s) H(s)= (s+2)/(s+1)(s-1).Comment on the stability of the system. (12)


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UNIT-V

COMPENSATOR DESIGN

PART-A

1. What is the Compensation?

2. Write the necessary frequency domain specifications for design of a control system.

3. What are the different types of compensator?

4. Sketch an electric lag-lead network of a lag-lead compensator.

5. Sketch an electric lead network of a lead compensator.

6. Draw the bode plot of a lead compensator.

7. What is lag compensator?

8. Write the transfer function of a typical lead-lag compensator.

9. What is lag-lead compensator?

10. Sketch an electric lag network of a lag compensator.

PART-B

1. Explain the design procedure of a lag compensator. (12)

2. Explain the design procedure of a lag-lead compensator.

(12)

3. The open loop transfer function of a certain unity feedback control system is given by

G(s)=K/s(s+1).It is desired to have the velocity error constant , Kv =10 and the phase

margin to be at least 60o. Design a suitable lag series Compensator. (12)

4. Explain the design procedure of a lead compensator.

(12)

5. Design a suitable lag compensator for the system with transfer function

G(s)=0.025/s(1+0.5s)(1+0.05s) to give velocity error constant of 20 sec and phase

margin of 40o. (12)

control system (pt)

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