SPECIAL ELECTRICAL MACHINES NOV/DEC 2007 seventh semester EEE anna university

Seventh semester
(Regulation 2004)
Electrical and Electronics Engineering
(Common to B.E.(Part Time) Sixth Semester regulation 2005)
Time : Three Hours Maximum: 100 marks
Answer all questions
PART A –(10x2=20)
1. What is a vernier motor?
2. Write down any two properties of synchronous reluctance motor.
3. What is holding torque in stepping motor?
4. What is hybrid motor/
5. List out any four applications of switched reluctance motor.
6. What are the type of power controllers used for switched reluctance motor?
7. What are the types of permanent magnet DC motor?
8. What is permanent magnet DC commutator motor?
9. List out the difference between the PMBLDC motor and PM synchronous motor.
10. What is meant by slot less motor?

PART B – (5x16 = 80 marks)

11.(a) (i) Explain the principle of operation and constructional features of synchronous reluctance motor. (9)
(ii) Explain the working of vernier motor with neat diagram. (7)
(b) (i) Explain the circle diagram and torque speed characteristics of synchronous reluctance motors. (9)
(ii) Explain the synchronous reluctance of PM synchronous reluctance motors. (7)

12.(a) Explain the construction and principle of operation of VR stepping motor in detail. (16)
(b) (i) Write short notes about the drive circuits of stepping motors? (6)
(ii) Explain the principle of operation and constructional features of hybrid motors in detail. (10)

13. (a) (i) Draw and explain the characteristics of SR motor in detail. (10)
(ii) Explain the shaft position sensing of SR motor. (6)
(b) (i) Explain the constructional features of SR motor I detail. (9)
(ii) Explain the role of computers in the control of SR moor. (7)

14. (a) (i) Derive the torque and EMF equations of the permanent magnet brushless DC motor. (10)
(ii) Explain the principle of operation of PMBLDC motor. (6)

(b) Explain the modes of operation of power controllers for PMBL DC motor with a neat diagram. (16)

15.(a) (i) Explain the principle of operation of permanent magnet synchronous motors. (6)
(ii) Derive the EMF and Torque equations of PMSM. (10)
(b) Explain the microprocessor based control of PMSM with neat block diagram and list out the advantages. (16)
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