KSR INSTITUTE FOR ENGINEERING AND TECHNOLOGY, TIRUCHENGODE 637 215.

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

EE6703 SPECIAL ELECTRICAL MACHINES
IMPORTANT QUESTIONS PART B
Name :
UNIT I SYNCHRONOUS RELUCTANCE MOTORS
1. a) Draw the phasor diagram of synchronous reluctance motor.(7) CO1 K3(AU/NOV-15,
MAY 12,NOV-08)
Investigate the performance of the synchronous reluctance motor with neat phasor
diagram.CO1 K4 (7) (AU/MAY-15, NOV-11 DEC 16) 1.23 to
Explain the steady state phasor diagram of Synchronous motor.(7)CO1 K2 (AU/NOV-12, 1.27
NOV-10)
Derive the expression the torque equation for the synchronous reluctance motor.CO1 K3
(AU/MAY-15, 17 DEC 16)
b) Explain the construction of radial and axial flux machines. Discuss the advantages and
disadvantages of each construction.(8) CO1K2 (AU/NOV-15, NOV-11, MAY-13). 2.5 to
Explain the construction and operation of Axial and Radial flux motors with neat diagram. 1.7
(8) CO1 K2(AU/MAY-15 AU APR/MAY 17)
3. Explain in details the operating principle and construction of synchronous reluctance 1.1 to
motor with neat diagrams. Derive the torque equation of synchronous reluctance motor. 1.9&
(13) CO1 K2(AU/NOV15,MAY-13,NOV-12,MAY-09,NOV-08,MAY-08, NOV-07, 1.23 to
DEC16) 1.27
4. a) Discuss the various stator current modes in synchronous reluctance motor in detail.
CO1 K2(8)(AU/NOV-14) 1.9 to
b) Write a detailed technical note on the variable reluctance and hybrid motors and their 1.12
advantages. CO1 K1(7) (AU/NOV-14) (AU/NOV-11)
5. a) Derive the open circuit emf of Synchronous reluctance motor. CO1 K3 (7)(AU/NOV-
10, NOV-08) 1.13 to
b) Derive the expression for d-axis synchronous reactance of a permanent magnet 1.23
Synchronous reluctance motor.(8) (AU/NOV-10, MAY-09, MAY-17) CO1 K3 A7 to
Explain the synchronous reactance of PM synchronous reluctance motors.(8) (AU/NOV A11
-07) CO1 K2
6. Explain the circle diagram and torque speed characteristics of synchronous reluctance
1.28
motor.(AU/NOV-09,NOV-08,NOV-07) CO1K2
7. (a) Draw and explain the typical speed torque characteristics of a reluctance motor.(8) 1.27 to
(AU/MAY-09) CO1 K2 1.28
(b) Distinguish between Axial and Radial air gap motors.(7) (AU/MAY-09) CO1 K2 &1.38
UNIT II STEPPER MOTORS
1. a) Explain microprocessor based control of stepper motor with an example.(9) (AU/NOV-
15,MAY-13) APR/MAY 2017 CO2 K2 2.74 to
b) What are the advantages of closed loop control of stepper motor?(4) (AU/NOV-15) 2.78
CO2 K1
2. Describe the operation of a variable reluctance type stepper motor with different modes of
operation.(13) (AU/NOV-15,NOV-12,NOV-09,MAY-08, NOV-07 DEC 16) CO2 K2
Describe construction working of variable reluctance stepper motor with neat diagram. 2.7 to
(13) APR/MAY 2017 CO2 K2 2.17
Explain the modes of excitation of a stepper motor with neat diagram. (13) (AU/NOV-10)
(AU/NOV-10 DEC 17) CO2 K2
3. a) Construct and evaluate the operation of single stack and multi-stack stepper motor with
neat diagram.(8) (AU/MAY-15, MAY-12, MAY-13 DEC 17) CO2 K3 2.38 to
b) Compare the static and dynamics characteristics of stepper motor with necessary 2.43
diagrams.(7) (AU/MAY-15, MAY-09 DEC 17) CO2 K2
4. Discuss the construction and working principle of Hybrid stepper motor with neat 2.29 to
 diagrams. (13) (AU/NOV-14, MAY-08, NOV-07) CO2 K2
2.31
Explain the working of hybrid motor. (13) (AU/MAY-12, NOV-09, NOV-08) CO2 K2
5. Draw and explain the power drive circuits and their performance characteristics for
stepper motor. (13) (AU/NOV-14,NOV-09, NOV-08, NOV-07 MAY 17) CO2 K3
Write a detailed technical note on the bipolar drives for stepper motors.(7) CO2 K4
2.54 to
(AU/NOV-12)
2.65
Discuss dual voltage driver circuit for two phase on drive of a four phase stepper motor
and explain the nature of current build up in dual voltage drive. (8) (AU/NOV-11) CO2 K
Write short notes on mini step drive.(7) (AU/NOV-08) CO2 K1
6. a) Discuss the principle of operations of permanent magnet stepper motor with torque Vs
angle characteristics. (7) (AU/MAY-12, NOV-11) CO2 K2
Draw and explain the torque pulse rate characteristics of a stepper motor.(8) (AU/NOV-09)
CO2 K3 2.17 to
Explain torque verses stepping rate characteristics of a stepper motor. Also explain about 2.29
slew range and Damping. (8) (AU/NOV-08, MAY-08) CO2 K2
b) What is the role of suppressors in drive circuit of stepping motor? Explain the different
types of suppressors circuit with neat diagrams.(7) (AU/NOV-12)
7. a)With a neat sketch, explain the different types of Logic sequencers for a stepper motor 2.48 to
(7) (AU/NOV-10) CO2 K2 2.53&
b)A stepper motor has the resolution of 180 step/rev. Compute the pulse rate required to 2.82
obtain the rotor speed of 2400 rpm.(8) APR/MAY 2012 CO2 K3 (9)
8. a)What is stepping angle? A VR stepper motor 8 poles in the stator and they have five 2.80
teeth in each pole. If the rotor has 50 teeth, calculate the step angle and resolution.(7) (2),
(AU/NOV-09,MAY-08) CO2 K3 2.81
b)A single stack, 3 phase variable reluctance motor has a step angle of 15 degree. (5)
Compute the number of stator and rotor poles.(8) (AU/NOV-12,08) CO2 K3 2.81
UNIT III SWITCHED RELUCTANCE MOTORS (SRM)
1. a)Explain with neat diagrams the constructional details and operation of rotary and linear
3.6 to
switched reluctance motors.(10) (AU/NOV-15,08,MAY-13) CO3 K2
3.14
Construct and demonstrate the operation of switched reluctance motor with neat diagram.
(10) (AU/MAY-15, 17) CO3 K3
b) What are application and advantages of SRM? (3) MAY 2017 3.48
3. a) Derive the voltage and torque equations of SRM.(8) (AU/ DEC 12 MAY-15) CO3 K3 3.4 to
Derive the torque expression for Switched reluctance motor.(8) (AU/NOV-10,16) CO3 K 3.6
Derive the torque equations of the variable reluctance motor and illustration the various 3.41 to
dependent parameters.(8) (AU/NOV-14) CO3 K3 3.42
b) Discuss the need of rotor position sensor in SRM.(7) (AU/MAY-15,13) CO3 K2 4.27 to
Discuss the sensor less operation and its advantages of switched reluctance motor.(7) 4.36
(AU/MAY-13 NOV 15) CO3 K2 Page No 3.56 to 3.57
5. a) Discuss the microprocessor based control of switched reluctance motor.(9) (AU/NOV- 3.52 to
12, 11, 14, 10, 09, 08,16 MAY 17) CO3 K2 3.56
b) Explain the torque-speed characteristics of switched reluctance motors. (4)(AU/NOV- 3.46 to
12,10,16) CO3 K2 3.48
6. Discuss the various converter topologies for a 3 phase switched reluctance motor with
merits and demerits of each. Explain any two of them.(13) (AU/NOV-11,16 MAY 17)
CO3 K2
Explain with neat circuit any two configurations of power converters used for the control
3.14 to
of switched reluctance motor.(13) (AU/NOV-15,08) CO3 K2
3.24
Explain briefly the various modes of excitation of variable reluctance motor.(13)
(AU/NOV-14) CO3 K2
Enumerate the various operating modes of SR motors with neat diagrams.(13) (AU/NOV-
12) CO3 K2
7. a) Along with circuit diagrams explain the hysteresis type and PWM type current 3.49 to
 regulator for one phase of a switched reluctance motor.(7) (AU/NOV- 09,14) CO3 K2
3.51
b) Explain the non linear analysis of SRM.(8) (AU/NOV-10) CO3 K2
UNIT IVPERMANENT MAGNET BRUSHLESS DC MOTORS
1. a) What are the advantages of BLPM dc motor over conventional dc motor?(4) (AU/NOV-
4.12 to
15) CO4 K1
4.15
b) Explain the construction and principle of operation of PMBLDC motor with neat
4.23 to
diagram and also compare with conventional DC motor.(9) (AU/NOV-09,08,16,MAY 17)
4.27
CO4 K2
2. From the magnetic circuit analysis of permanent magnet brushless DC motor. Derive the
expression for permeance coefficient.(13) (AU/NOV-15,MAY-13) CO4 K3 4.64 to
Derive the equation for permeance coefficient (PC) of BLDC motor.(13) (AU/NOV-10) 4.68
CO4 K3
3. Derive the EMF equation and torque equation of PMBLDC motor.(13) (AU/NOV- 4.48 to
15,10,08,MAY 17) CO4 K3 4.51
4. Discuss the hysteresis type current regulation of PMBLDC motor with neat diagram.(13)
(AU/MAY-15) CO4 K2
Illustrate the working of different types of power controllers used for the control of 4.40 to
permanent brushless D.C. motors. (13) (AU/MAY-13, DEC 16) CO4 K4 4.42
Sketch the structure of controller for PMBL DC motor and explain the functions of various
blocks(13). (AU/NOV-12, 09) CO4 K3
5. a)A PMBLDC motor has constant 0.12 Nm/A referred to DC supply. Compute the motors
no-load speed when connect to 48V DC supply. Find the stall current and torque if
4.74
armature resistance is 0.15/phase and drop in controller transistor is 2V.(7)(AU/NOV-12)
CO4 K4
A permanent magnet DC commutator motor has a no-load speed of 600 rpm when
connected to a 120 c supply. The armature resistance is 2.5 and rotational and iron losses
4.75
may be neglected. Determine the speed when the supply voltage is 60 V and the torque is
0.5 Nm.(7) (AU/NOV-12,16) CO4 K4
b) Distinguish between mechanical and electronic commutators.(8) (AU/NOV-11,10) CO4
K2
Draw the diagram of electronic commutator.Explain the operation of the same. (8)
4.17
(AU/NOV-11) CO4 K3
To
Describe the constructional aspects of mechanical and electronic commutator of PMBLDC
4.21
motors. (8) (AU/NOV-12) CO4 K2
Analysis the operation of electronic commutator in PMBLDC motor with neat diagram. (8)
(AU/MAY-15)
8. Illustration in detail, the operation of PMBLDC motor with 180 magnet arcs and 120
square-wave phase currents.(13) (AU/NOV-12) CO4 K4 4.55 to
Explain with neat diagram and waveforms of the full wave inverter based PMBLDC 4.63
motor. (13) (AU/NOV-08) CO4 K2
UNIT VPERMANENTMAGNETSYNCHRONOUSMOTORS
1. Explain the construction and performance of a permanent magnet synchronous motor with
neat diagram.(13) (AU/NOV-09,MAY 17) CO5 K2 7.2 to
Discuss the different rotor configuration of PM synchronous machines.(13) (AU/NOV- 5.6
12) CO5 K2
2. Derive the EMF and torque equation of permanent magnet synchronous motor.(13)
(AU/NOV-15,16 MAY-13,08, 17) CO5 K3
5.6 to
Derive the expression for the torque developed in a brushless PMSM along with phasor
5.21
diagram. (13) (AU/NOV-12, 16) CO5 K3

3. Draw and discuss the various power controllers used in PMSM with neat diagram.(13)
5.31 to
(AU/MAY-15, 10,09) CO5 K3
5.38
Explain the power controllers used in PMSM.(13) (AU/NOV-15) CO5 K2
4. a)Derive the expression for power input and torque of a PMSM. Explain how its torque 5.6 to
speed characteristics are obtained.(8) (AU/NOV-11) CO5 K3 5.21
Enumerate the speed-torque characteristics of PMSM diagrams.(8) (AU/NOV-14,16 5.39
MAY-13,08) CO5 K3 5.31
b)Write a detailed note on microprocessor based control in PMSM.(7) (AU/NOV-12,08)
5. Write short note on: i) Armature reaction in PMSM. (AU/MAY-15) CO5 K1
5.21 to
ii) Synchronous Reactance. (AU/MAY-15)
5.24
Derive an expression for synchronous reactance of PMSM. (AU/NOV-15) CO5 K3
6. a)Discuss the current control operation scheme of PMSM in details.(8) (AU/NOV-14)
CO5 K2 5.35 to
b) Write short notes on: Volt-ampere requirements in PMSM motor. (7)(AU/MAY-13) 5.38
CO5 K1 5.43 to
Compare the volt-ampere and torque/ampere of a BLDC with PMSM.(8) (AU/NOV-10) 5.44
CO5 K2
7. a) Write a detailed technical note on vector control of BLPMSM. (AU/NOV-12) CO5 K1 5.35 to
Describe in detail the vector control of PMSM. (AU/NOV-11) CO5 K1 5.38
b) Derive self and mutual inductance of Permanent magnet synchronous motor. 5.24 to
(AU/NOV-10) CO5 K3 5.26
Explain with phasor diagram, the measurement of Ld and Lq in PMSM. (AU/NOV-08) 5.27 to
CO5 K2 5.30