Friday, 20 April 2012

SPECIAL ELECTRICAL MACHINES IVEEE - QB


SRI KRISHNA ENGINEERING COLLEGE
Panapakkam, Chennai – 601 301.

Department of Electrical and Electronics Engineering

Question Bank

Subject: EE 1001 SPECIAL ELECTRICAL MACHINES IVEEE

UNIT–I  SYNCHRONOUS RELUCTANCE MOTOR
PART – A
1.       What is synchronous reluctance motor?
2.       What are the advantages and disadvantages of synchronous reluctance motor?
3.       Mention some applications of synchronous reluctance motor.
4.       Define synchronous reluctance.
5.        Define reluctance torque.
6.       Distinguish between axial and radial air gap motors with relevant figures.
7.        Draw the steady state phasor diagram of synchronous reluctance motor.
8.       List out the primary design considerations of synchronous reluctance motor.
9.       State the advantages of synchronous reluctance motor over             PM machines.
1    What are factors to be considered while designing a vernier motor?
PART – B
1.       Explain the constructions and working principle of synchronous reluctance motor.
2.       Explain in detail about classification of synchronous reluctance motor.
3.        Draw and explain the phasor diagram of synchronous reluctance motor.
4.        Derive the torque equation of synchronous reluctance motor and vernier motor.
5.       Draw and explain the characteristics of synchronous reluctance motor.
6.        Explain in detail about vernier motor.




UNIT – II        STEPPER MOTOR
PART – A
1.       What is stepper motor?
2.        Define step angle.
3.       Define slewing.
4.       Sketch the diagram of a VR Stepper motor.
5.        What are the different modes of excitation used in variable reluctance stepper motor? 
6.        Mention some applications of stepper motor
7.        Define resolution.
8.       What are the advantages and disadvantages of stepper motor?
9.        What is meant by micro stepping in stepper motor?
10.    Define holding torque.
11.    Define detent torque.
12.    Define pull-in torque and pull-out torque.
13.     Draw the typical dynamic characteristics of a stepper motor.
14.     What is slew range?
15.    What is synchronism in stepper motor?
16.    Draw the block diagram of the drive system of a stepper motor.
17.    What is the step angle of a four phase stepper motor with 12 stator teeth and 3 rotor teeth?
18.    A single stack, 3-phase VR motor has a step [angle of 15°. Find the number of its rotor and stator poles.
19.    What are the advantages of stepper motor?
20.    What are the disadvantages of stepper motor?

PART B

1.        Explain the construction and various modes of excitation of        VR stepper motor.
2.       Explain the construction and various modes of excitation of PM stepper motor.
3.        Explain the construction and working principle of Hybrid Stepper motor.
4.        State and explain the static and dynamic characteristics of a stepper motor.
5.        Explain in detail about different types of power drive circuits for stepper motor.
6.        Explain the mechanism of torque production in VR stepper motor.
7.       Draw and explain the drive circuits for stepper motor. 


UNIT – III   SWITCHED RELUCTANCE MOTOR
PART – A
1.       What is switched reluctance motor?
2.       What are the essential differences between a stepper motor and SRM?
3.        Mention any four advantages of switched reluctance motor.
4.       Mention some applications of SRM.
5.        Draw the simple block diagram of SRM.
6.        What is the different power controllers used for the control of SRM?
7.        Why rotor position sensor is essential for the operation of SRM?
8.        What is meant by energy ratio?
9.        What is phase winding?
10.    What is switched reluctance motor?
11.    What are the advantages of SRM?
12.    What are the disadvantages of a switched reluctance motor?
13.    Why rotor position sensor is essential for the operation of                 switched reluctance motor?
14.     What are the essential difference between SRM and stepper motor?
15.     What is phase winding?
16.     What are the basic requirements of power semiconductor switching circuits?
17.     What are the merits and demerits of the converter circuit having two power semiconductor devices and two diodes per phase?
18.    What are the merits and demerits of converter having phase winding with bifilar wires?
19.    What are the merits and demerits of split link converter?
20.    What the .merits and demerits of 'c' dump converter?
21.    What are the two types of control techniques in SRM?
22.    What are the modes of operation of SRM?


PART – B
1.       Explain the construction and working principle of switched reluctance motor.
2.        Describe the various power controller circuits applicable to switched reluctance motor and explain the operation of any one scheme with suitable circuit diagram.
3.        Draw a schematic diagram and explain the operation of a ‘C’ dump converter used for the control of SRM.
4.       Draw and explain the general torque-speed characteristics of SRM and discuss the type of control strategy used for different regions of the curve. Sketch the typical phase current waveforms of low speed operation.
5.       .a. Derive the torque equation of SRM.
 b. Write note on the power controllers used in switched reluctance       motors
6.       Describe the hysteresis type and PWM type current regulator for single  phase of a SRM with relevant circuit diagrams
7.       With neat diagram, explain the microprocessor based control of switched reluctance motor.



UNIT – IV    PERMANENT MAGNET BRSHLESS DC MOTOR
PART – A
1.       What are the advantages and disadvantages of brushless dc motor drives?
2.       Write the torque and emf equation of square wave brushless motor.
3.        Mention some applications of PMBL DC motor.
4.        Why the PMBLDC motor is called electronically commutated motor?
5.        What is the classification of BLPM DC motor?
6.        What are the two types of BLPM SQW DC motor?
7.        Name the position sensors that are used for PMBL DC motor.
8.       State the two classifications of PM synchronous machines and the types in each.
9.        What is meant by slot less motor?
10.    Distinguish between self control and vector control of PMSM self control
11.    What are the advantages dc brushless dc motor drives?
12.     What are the disadvantages dc brushless dc motor drives?
13.     List out the various permanent magnet materials.
14.     Draw the magnetic equivalent circuit of 2 pole permanent magnet brushless dc motor
15.    Why a PMBLDC motor is called an electronically commutated motor?
16.     Write the torque and emf equation of square wave brushless motor.
17.     Mention some applications of PMBLDC motor.
18.     What are the differences between the mechanical and electronic Commutator?
19.     What are the difference between the conventional dc motor and PMBLDC motor?
20.     What are the classifications of PMBLDC motor?
21.     What are the two types of rotor position sensors?
22.     What are the materials used for making Hall IC pallet?
23.    A permanent magnet dc Commutator motor has a no-load speed of 6000 rpm when connected to a 120 V supply. The armature resistance is 2.5 Ω and rotational and iron losses may be neglected. Determine the speed when the supply voltage is 60 V and the torque is 0.5 Nm.
PART- B
  1. Explain the construction and principles of   operation of PMBL dc motor with neat diagram
  2. Describe the operation of power controllers for PMBLDC motor with neat diagram.
  3.  Explain the construction and performance of a permanent magnet synchronous motor with neat diagram
  4. Derive the emf and torque equations permanent magnet synchronous motor
  5. ( i) Explain the speed -torque characteristics of PMDC.
(ii)Explain with phasor diagram & measurement of Ld and Lq in           PMSM.
  1. (i)Explain the speed- torque characteristics of PMSM.
               (ii) Explain the working of microprocessor based control
                     in PMSM.
  1. Drive the expressions for the emf and torque of a PMBLDC motor.
        8.    Explain the closed loop control scheme of a permanent magnet                          brushless DC motor drive with a suitable schematic diagram
  1.  Draw the diagram of electronic Commutator. Explain the operation of electronic Commutator.
  2. (i) Explain with neat diagram and wave forms of the full wave                 inverter based PMBLDC motor
       (ii)Draw and explain the speed –torque characteristics of PMBLDC             motor
  1. Sketch the structure of controller for PMBLDC motor and explain the functions of various blocks.
  2. Explain the closed loop control scheme of a permanent magnet brushless dc motor drive with a suitable schematic diagram.
  3. Discuss the use of Hall sensors for position sensing in PMBLDC motor.



UNIT – V PERMANENT MAGNET SYNCHRONOUS MOTOR
PART – A
  1. What is permanent magnet synchronous motor?
  2.  What are the advantages and disadvantages of PMSM?
  3. What are the applications of PMSM?
  4.  What are the different types of PMSM?
  5.  Compare electromagnetic excitation with permanent magnet of PMSM.
  6.  Clearly explain the differences between the synchronous reluctance motor and PMSM.
  7.  What are the differences in the constructional features of PMBLDC motor and PMSM?
  8.  Write the emf equation of PMSM.
  9.  What is meant by self control?
  10.  What is ‘pulsed mode’?
  11.  What is load commutation?
  12.  A three phase, four pole, brushless PM rotor has 36 stator slots. Each phase winding is made up of three coils per pole with 20 turns per coil. The coil span is seven slots. If the fundamental component of magnet flux is 1.8 mWb. Calculate the open circuit phase emf (Eq) at 3000 rpm.
PART – B
  1. Explain the construction and operation of PMSM.
  2.  Explain the principle of operation of a sine wave PM synchronous machine in detail. Draw its phasor diagram and derive its torque equation.
  3. Derive the emf equation of PMSM.
  4.  Write about Self control of PMSM.
  5.  Derive the expressions for power input and torque of a PMSM. Explain how its torque speed characteristics are obtained.
  6.  Explain in detail the vector control of permanent magnet synchronous motor.




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