Anna University Chennai 2008-7th Sem B.E Electrical and Electronics Engineering ./B.Tech , IL/ ,ester,(Regulation 2004),,EE 1001 – SPECIAL ELECTRICAL MACHINES - Question Paper

B.E./B.Tech DEGREE EXAMINATION, APRIL/MAY 2008
Seventh semester
(Regulation 2004)
Electrical and Electronics Engineering
EE 1001 – SPECIAL ELECTRICAL MACHINES
(Common to B.E.(Part Time) 6th Semester regulation 2005)
Time : 3 Hours Maximum: 100 marks
ans all ques.
PART A –(10x2=20)


1. What are the kinds of synchronous reluctance motor
2. List the application of vernier motor.
3. What are the main features of stepper motor which are responsible for its wide spread use?
4. Define the term stepping angle.
5. Draw the speed torque characteristics of switched reluctance motor.
6. What is the working principle of switched reluctance motor?
7. Give the merits of PMBL DC motor compared to conventional motor.
8. What is meant by peak recovery current in PMBLDC motor?
9. Synchronous machines with surface-mount magnets have very little difference ranging from direct axis and quadrature axis inductances- why?
10. What is the magnitude of stator current in PMSM to achieve demagnetization?
11.
PART B – (5x16 = 80 marks)

11.(a) discuss the constructional details and working principle of synchronous reluctance motor. (16)
(OR)
(b) (i) draw and discuss a typical torque – speed characteristics of a synchronous reluctance motors. (9)
(ii) discuss the working principle of vernier motor. (7)

12.(a) (i) define the operation of variable reluctance kind stepper motor. Also discuss about micro stepping. (9)
(ii) discuss the working of hybrid motor. (7)
(OR)
(b) (i) discuss torque versus stepping rate characteristics of a stepper motor. Also discuss about slew range and damping. (10)
(ii) What is stepping angle? compute the stepping angle for a three phase 24 pole permanent magnet kind stepper motor. (6)

13.(a)(i) discuss with neat diagram, the constructional details and working principle of switched reluctance motors. (9)
(ii) Write a note on power controllers used in switched reluctance motors. (7)
(OR)
(b) discuss with a neat block diagram, the microprocessor based control in switched reluctance motors. (16)

14.(a)(i) discuss the principle of operation of PMBLDC motor. (8)
(ii) Derive the emf formula of PMBLDC motor. (8)
(OR)
(b)(i) discuss with neat diagram and waveforms the full wave inverter based PMBLDC motor. (9)
(ii) Draw and discuss the speed torque characteristics of PMBLDC motor. (7)

15.(a)(i) Derive the torque formula in PMSM.(8)
(ii) discuss with phasor diagram, the measurement of Ld and Lq in PMSM.(8)
(OR)
(b)(i) discuss the speed torque characteristics in PMSM. (8)
(ii) discuss the working of microprocessor based control in PMSM. (8)

Earning:   Approval pending.