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EE 6703 Special Electrical Machines Question Bank
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R.M.K COLLEGE OF ENGINEERING AND TECHNOLOGY
R.S.M. NAGAR, PUDUVOYAL – 601 206
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
EE 6703 SPECIAL ELECTRICAL MACHINES QUESTION BANK
UNIT I SYNCHRONOUS RELUCTANCE MOTORS 9
Constructional features –Types –Axial and Radial flux motors –Operating principles–Variable Reluctance Motors –
Voltage and Torque Equations -Phasor diagram-performance characteristics –Applications
PART A
1. State the properties of synchronous reluctance motor.
They have several useful properties, including:
ď‚· High output power capability
ď‚· Ability of the rotor to withstand high speeds.
ď‚· Negligible zero-torque spinning loss.
ď‚· High reliability.
ď‚· combined reluctance and magnet alignment torque;
ď‚· field-weakening capability;
ď‚· under-excited operation for most load conditions;
ď‚· high inductance;
ď‚· high speed capability; and
ď‚· High temperature capability.
2. List the various types of synchronous reluctance motor.
The main types are 1. Cageless. 2. Line -start.
According to the magnetization 1. Radial type. 2. Axial type.
2. Distinguish between axial and radial air gap rotors.
3. Write the torque equation of synchronous reluctance motor.
5. Define reluctance torque.
The torque exerted by the reluctance motor because of the tendancy of the salient poles to align themselves
in the minimum position. This torque is called reluctance torque.
6. Draw the torque angle characteristics of synchronous reluctance motor.
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7. Draw the speed – torque characteristics of synchronous reluctance motor.
8. Draw the Phasor diagram of synchronous reluctance motor.
9. Give the advantages and disadvantages of synchronous reluctance motor.
The advantages of SyRM.
There is no concern with demagnetization, hence synchronous reluctance.
There need be no excitation field at zero torque, thus eliminating electromagnetic spinning losses.
SyRM rotor can be constructed entirely from high strength, low cost materials.
Lower torque ripple.
Disadvantages of SyRM.
Compared to induction motor it is slightly heavier and has low power factor.
High cost than induction motor.
Need speed synchronization to inverter output frequency by using rotor position
sensor and sensor less control
10. What are the design considerations of synchronous reluctance motor?
1. Power factor. 2. Copper loss and core loss. 3.Cost. 4.Efficiency
11. What are the advantages of increasing Ld/Lq ? ratio in synchronous reluctance motor.
1. Motor power factor increases.
2. I2R Losses reduced.
3. Reduced volt ampere ratings of the inverter driving the machine.
12. What are the applications of synchronous reluctance motor
ď‚· metering pumps and industrial process equipment
ď‚· Fiber spinning mills
ď‚· Industrial process equipment
ď‚· Metering pumps
ď‚· Wrapping and folding machines.
13. Define reluctance.
The property of a magnetic circuit of opposing the passage of magnetic flux lines, equal to the ratio of the
magnetomotive force to the magnetic flux.
14. What is synchronous reactance?
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Synchronous reactance is a combination of armature winding leakage reactance and a reactance used to
represent armature reaction.
15. What is hybrid motor?
Synchronous hybrid motor (HSM) combines positive properties of reluctance motors and
synchronous permanent-magnet motors . SynPM machines have adjustableair gap flux density
compared with the PM machine. The otheris that the armature reaction inductance of SynPM
machine islower than synchronous machine and higher than normal PMmachine placing it in a
desirable range for the purpose of controlling terminal voltage.
16. What is SYNREL motor?
It is the motor driven by reluctance torque which is produced due to tendency of the salient rotor
poles to align themselves with synchronously rotating field produced by stator.In this motor, the
magnets are left out of the rotor or they are demagnetized. The rotor of the SyRM has salient poles
but neither have field windings nor permanent magnets.
17. Synchronous reluctance motor is a self starting motor.True or False.
18. Power factor of synchronous reluctance motor is increased by increasing saliency ratio.True or False.
19. Efficiency of synchronous reluctance motor is high compared to doubly excited machine. True or False.
20. Compare synchronous reluctance motor with conventional synchronous motor.
21. What are the types of rotor in synchronous reluctance motor?
ď‚· Salient rotor
ď‚· Radially laminated rotor
ď‚· Axially laminated rotor.
22. When does a PM synchronous motor operate as a SyRM.
If the cage winding is induced in the rotor and the magnets are left out or demagnetized, a PM SyRM
operates as a SyRM.
23. Write the operating principle of SyRM.
When a piece of magnetic material is free to move in a magnetic field, it will align itself with the magnetic
field to minimize the reluctance of the magnetic circuit.
24. What is Vernier motor.
Vernier motor is a PM motor and has a high torque at low speed. It operates on the principles of a vernier.
25. Define power factor of syrm
PF max=(Ld/Lq-1)/(Ld/Lq+1)
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Higher Ld/Lqratos yield higher power factors,which corresponds to reduced I2
R losses and reduce volt
ampere ratings of the inverter driving the machine.
PART B
1. With a neat sketch explain the constructional features and principle of operation of synchronous reluctance motor.
2. Draw the steady state phasor diagram synchronous reluctance motor and develop torque equation.
3. Compare the constructional features of axial and radial air gap synchronous reluctance motor.
4. Draw and explain speed – torque characteristics and torque angle characteristics of synchronous reluctance motor.
5. Explain circle diagram and torque –speed characteristics of synchronous reluctance motor.
6. Draw and explain typical speed -torque characteristics of reluctance motor. Compare a reluctance motor with an
equivalent induction motor.
7. Distinguish between axial and radial air gap motors with relevant figures.
8. Discuss the main advantages and disadvantages of synchronous reluctance motor.
9. Enumerate the design considerations of synchronous reluctance motor.
10. Discuss the various applications of synchronous reluctance motor.
UNIT II STEPPER MOTORS 9
Constructional features –Principle of operation –Variable reluctance motor –Hybrid motor –Singleand multi
stack configurations –Torque equations –Modes of excitation –Characteristics –Drive circuits–Microprocessor
control of stepper motors –Closed loop control-Concept of lead angle–Applications
PART A
1. What is stepper motor.
Stepper motor is a digital actuator whose input is in the form of programmed energization of the stator
windings and whose output is in the form of discrete angular rotation.
2. Draw the basic block diagram of stepper motor.
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3. Define the term step angle.
Step angle is defined as the angle through which the stepper motor shaft rotates for each command pulse.
It is denoted as β. β=(Ns-Nr/Ns.Nr)360 (or)360/(mNr)
4. Define resolution.
It is defined as the number of steps needed to complete one revolution of the rotor shaft
5. List the various types of stepper motor.
ď‚· Variable reluctance stepper motor.
ď‚· Permanent magnet stepper motor.
ď‚· Hybrid stepper motor.
6. List the applications of stepper motor.
Floppy disk drives, Quartz watches, Camera shutter operation, Dot matrix and line printers, Robotics,
Machine tool applications, . robotics
7. What are the different modes of operation of VR stepper motor?
ď‚· 1-phase on or full step operation.
ď‚· 2-phase on mode.
ď‚· Half step operation.
ď‚· Micro stepping operation.
8. What are the different modes of excitation of VR stepper motor?
9. What do you mean by full step and half step operation?
Full step operation: It is the one-phase on mode operation. It means, at that time only one winding is
energized. By energizing one stator winding, the rotor rotates some angle. It is the full step operation.
Half step operation: It is the alternate one phase on and 2 phase on mode operation.Here the rotor rotate in
each step angle is half of the full step angle.
10. What is meant by microstepping of stepper motor?
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Response range is the range of stepping rates at which the stepper motor will start or stop, without losing
synchronism, against a given load torque
19. What is slewing range of stepper motor?
slewing range is the range of stepping rate at which the stepper motor can run in the slowing mode , with
losing synchronism, against a given load torque
20. Draw the typical static characteristics of stepper motor.
21. Draw the typical dynamic characteristics of stepper motor.
22. A stepper motor has a step angle of 1.8° and is driven at 400pps. Determine i)Resolution, ii) Motor speed and
iii) number of pulses required to rotate the shaft through 54°.
23. Calculate the pulse rate required to obtain a rotor speed of 2400 rpm for a stepper motor having a resolution of
250 steps/rev.
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24. A stepper motor has a resolution of 500 steps/rev in the single phase ON mode of operation. If it is operated in
half step mode, determine i) resolution, ii) number of steps required to turn the rotor through 72°.
25. A four stack VR stepper motor has a step angle of 1.5°, find the number of its rotor and stator teeth.
26. What is logic sequencer?
Logic sequence generator generates programmed logic sequences required for operation of a stepper motor.
27. What is the use of current suppression circuit?
This circuit is used to ensure fast decay of current through the winding when the transistor is turned off
28. What is meant by power drive circuit in stepper motor?
The output from the logic sequence generator signals are low level signals which are too weak to energize
stepper motor windings. To increase the voltage, current and power levels of the logic sequence output by
using power semiconductor switching circuit. This circuit is called power drive circuit.
29.What are the types of current suppression circuits?
1. Diode suppression.
2. Diode-resistor suppression
3. Diode-zener diode suppression.
4. Active suppression.
30.How is the step of PM stepper motor controlled?
The step of the PM stepper motor is controlled by energization of phase winding with positive or negative
current.
31. What is synchronism in stepper motor?
It is the one to one correspondence between the number of pulses applied to the stepper motor controller and
the number of steps through which the motor has actually moved
32. What are the advantages of hybrid stepper motor?
1. Less tendency to resonate.
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4. Explain the static and dynamic characteristics of a VR stepper motor with various specifications in them.
5. With a neat sketch explain the various modes of operation of VR stepper motor.
6. With a neat sketch explain the various drive circuits of VR stepper motor.
7. Explain open loop and closed loop control of stepper motor.
8. With a neat sketch explain the operation of two pole three stack VR stepper motor.
9. Derive the torque equation of VR stepper motor.
10. Explain torque Vs stepping rate characteristics of a stepper motor. Also explain about slew range, pull in range
and pull out range.
UNIT III SWITCHED RELUCTANCE MOTORS(SRM) 9
Constructional features –Rotary and Linear SRM -Principle of operation –Torque production –Steady state
performance prediction-Analytical method -Power Converters and their controllers –Methods of Rotor position
sensing –Sensor less operation –Characteristics and Closed loop control –Applications
PART – A
1. What is srm?
It is a doubly salient , single excited motor.this means that it has salient poles on both rotor and the stator.but
only one member carries winding.the rotor has no windings,magnets or case windings.
2. Compare rotary and linear SRM
It has wound field coils of a DC motor for its stator windings and has no coils or magnets on its rotor.
Linear switched reluctance motors (LSR Ms) are the counterparts of the rotating SRMs. In fact, the linear
switched reluctance motor is obtained from its rotary counterpart by cutting along the shaft over its radius
and rolling them out.
3. Why rotor position sensor is essential for the operation of switched reluctance motor?
It is normally necessary to use a rotor position for commutation and speed feedback. The
turning ON and OFF operation of the various devices of power semiconductor switching circuit are
influenced by signals obtained from rotor position sensor.
4. List the disadvantages switched reluctance motor?
1. Stator phase winding should be capable of carrying magnetizing current.
2. For high speed operation developed torque has undesirable ripples is a result develops
undesirable noises or acoustic noises.
3. It requires position sensors.
4. What are the advantages of switched reluctance motor?
ď‚· Construction is simple and robust.
ď‚· There is no permanent magnet.
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ď‚· Rotor carries no windings, no slip rings, no brushes, less maintenance
ď‚· Power semiconductor switching circuitry is simpler.
5. What are the applications SRM?
ď‚· Washing Machines.
ď‚· Vacuum cleaners.
ď‚· Fans
ď‚· Future auto mobile applications.
ď‚· Robotics control applications.
6. What are the two types of current control techniques?
ď‚· Hysteresis type model
ď‚· PWM type control.
8. What is meant by energy ratio?
Energy ratio = Wm / (Wm + R) = 0.45
Wm = mechanical energy transformed.
This energy ratio cannot be called as efficiency. As the stored energy R is not wasted as a loss but it is
feed back to the source through feed back diodes.
9. What is the phase winding?
Stator poles carrying field coils. The field coils of opposite poles are connected in series such that
mmf‟s are additive and they are called Phase windings of SRM
10. What are essential difference between SRM and Stepper motor?
1. In SRM is designed for continuous rotation.
SRM requires a rotor position sensor.
2. In Stepper motor is designed to rotate in step by step rotation.
It does not require rotor position sensor
11. Write down the torque equation for a switched reluctance motor drive.
T=1/2(i2
dL/dθ)
12. What is hysteresis current control?
This type of current controller maintains a more or less constant current throughout the conduction
period in each phase. This controller is called hysteresis type controller
13. What are the basic requirements of power semiconductor circuits?
14. Draw the torque speed characteristics of SRM.
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15. What are the effects of saturation in SRM.
In case of saturated motor, energy converted during the excitation cycle is greater than energy converted in
unsaturated condition. Thus energy ratio is more. Thus more mechanical work is extracted from the motor for the
same input energy. This reduces the nconverter rating for the same output power.
16. What are the two modes of operation of SRM.
1. Low speed operation mode
2. High speed operation mode.
17. What are the merits and demerits of converter having phase winding with bifilar wires.
18. Draw the λ-I curve of SRM.
19. What is hysteresis type current control?
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This type of current controller maintains a more or less constant current throughout the conduction
period in each phase. This controller is called hysteresis type controller
20. Define voltage pulse width modulation control.
In voltage control, a fixed switching frequency is used tomodulate the chopping transistor. The
PWM duty cycle isconstant during one electrical cycle, but it can be varied tocontrol the average
phase voltage:Vph= D Vdc ……………………..(1)
Where Vdc =dc-link voltage and D=PWM duty cycle whichis defined as the fraction of time that the
switch is on withrespect to the period of the switching frequency.
21. What are types of power controllers used for switched reluctance motor?
1. Using two power semiconductors and two diodes per phase.
2. (n+1) power switching devices and (n+1) diodes per phase.
3. Phase windings using bifilar wires.
4. Dump –C-converter.
5.Split power supply converter.
22. State the principle of operation of switched reluctance motor
.The SRM develops an electromagnetic torque due to variable reluctance principle. When air gap is
minimum, the reluctance will be minimum. Hence inductance will be maximum, so the rate of change of
inductance is zero.
When the reluctance varies, there will be a change in inductance so when a
Particular stator winding of SRM is excited, the rotor pole comes in alignment with that stator pole and
thus the rotor rotates.
23. What is meant by effectiveness in SRM?
In SRM, the energy stored in the magnetic field is not necessarily dissipated. With the appropriate
converter circuit, it can be recovered to the supply at the end period of rising inductance. Hence the term
effectiveness is used instead of efficiency.
19. State the need for non-linear analysis of switched reluctance motor
.Machine with linear magnetic characteristics means that it has constant magnetic permeability and no
magnetic saturation. In practice, the SRM which follows variable reluctance principle operates with its
magnetic material in saturation. As saturation tends to increase the size of the variable reluctance
machines for a given output, the non-linear analysis is required
PART – B
1. Draw and explain four converter topologies for three phase Switched Reluctance. Write the merits and demerits of
each. (Apr/May 2010)
2. With neat block diagram describe in detail the microprocessor based controller in SRM. (Apr/May 2010) and
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3. Explain the construction and working principle of SRM. (Nov /Dec 2007)
4. Draw and explain torque/ speed characteristic of SRM. (Apr/May 2010)
5. Explain in detail about torque prediction in SRM. (Nov /Dec 2007)
6. Explain in detail the control circuits used in switched reluctance motor.
7. Discuss the various modes of operation of SRM.
8. Derive the torque equation and develop the mechanical characteristics of SRM.
9. Explain the importance of closed loop control in switched reluctance motor.
10. Sketch the general torque speed curve of SR motor and discuss the type of control strategy used for different
regions of the curve.
UNIT IV PERMANENT MAGNET BRUSHLESS D.C. MOTORS 9
Permanent Magnet materials –Minor hysteresis loop and recoil line-Magnetic Characteristics –Permeance
coefficient -Principle of operation –Types –Magnetic circuit analysis –EMF and torque equations –
Commutation -Power Converter Circuits and their controllers–Motor characteristics and control–Applications
PART – A
1. What are the advantage and disadvantages of brush less dc motor drives?
Advantages
ď‚· Regenerative braking is possible
ď‚· Speed can be easily controllable
Disadvantages
ď‚· It requires a rotor position sensor
ď‚· It requires a power semiconductor switching circuits.
2. List the permanent magnet materials.
ď‚· Alnicos (Al, Ni, Co, Fe);
 •Ceramics (Ferrites) e.g. Barium ferrite BaO x 6Fe2and Strontium ferrite SrO x 6Fe2
ď‚· Rare earth materials i.e. Samarium cobalt SmCo and neodymium iron boron NdFeB.
3. What are differences between mechanical and electronic commutator.
Mechanical Commutator Electronic Commutator
It is made up of commutator segments and mica
insulation. Brushes are made up of carbon or graphite.
Power Electronic switching devices are used in the
commutator.
Commutator arrangement is located in the rotor. Commutator arrangement is located in the stator.
Shaft position sensing is inherent in the arrangement. It requires a separate rotor position sensor.
Number of commutator segments are very high. Number of switching devices is limited to 6.
Sliding contact between commutator and brushes. No sliding contacts.
Sparking takes place. There is no sparking.
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It requires a regular maintenance. It requires less maintenance.
Difficult to control the voltage available across tappings.
Voltage available across armature tappings can be
controlled by PWM techniques.
Highly reliable.
Reliability can be improved by specially designed devices
and protecting circuits.
4. Write the torque and Emf equation of square wave brushless motor.
5. Mention some applications of PMBLDC Motor.
Power alternators
Automotive applications
Computer and Robotics applications
Textile and Glass industries
6. Compare conventional dc motor and PMBLDC motor.
conventional Dc motor? PMBL DC motor
Field magents on the stator Field magents on the rotor
Maintenance is high BLPM sine wave motor
7. Give the classification BLPM dc motor?
ď‚· BLPM square wave motor
ď‚· BLPM sine wave motor
8. What are the two types of BLPMSQWDC motor?
ď‚· 1800
polerarc BLPM SQW motor
 120”polearc BLPM SQW motor
9. Compare PMBLDC motor and switched reluctance motor.
10. What is the permanent magnet DC Commutator motor?
A permanent magnet DC motor is very similar to that of a normal DC motor. The working principle of any DC
motor is same, i.e. when a current carrying conductor is placed in a magnetic field, it experiences a force. A
permanent magnet DC motor also works on the same principle.In a PMDC motor, permanent magnets (located
in stator) provide magnetic field, instead of stator winding. The stator is usually made from steel in cylindrical
form. Permanent magnets are usually made from rare earth materials or neodymium. The rotor is slotted
armature which carries armature winding. Ends of armature winding are connected to commutator segments on
which the brushes rest. Commutator is made from copper and brushes are usually made from carbon or
graphite. DC supply is applied across these brushes.
11. Why the PMBLDC motor is called electronically commutated motor?
"Brushless DC electric motor (BLDC motors, BL motors) also known as electronically commutated
motors (ECMs, EC motors) are synchronous motors that are powered by a DC electric source via an
integrated inverter/switching power supply, which produces an AC electric signal to drive the motor. In
this context, AC, alternating current, does not imply a sinusoidal waveform, but rather a bi-directional
current with no restriction on waveform. Additional sensors and electronics control the inverter output
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amplitude and waveform (and therefore percent of DC bus usage/efficiency) and frequency (i.e. rotor
speed).
12. What are the relative merits of the brushless dc motor drives?
13. What is hall sensor?
A Hall effect sensor is a sensor that response to a magnetic field. When the hall sensor is put in a
magnetic field the electrons running through will move to one side of the sensor. The sensor will then
have one positive and one negative side and create a voltage, known as Hall voltage.
The Hall effect sensor usage today:
Proximity (distance) detection, power sensing, speed detection, and current sensing applications. For example
time the speed of wheels and shafts, alarm systems, keyboard and printers.
The advantages of using a Hall effect sensors are:
• A "invisible” sensor. Non contact operation so there is no wear and friction. Hence unlimited number
of operating cycles
• High speed operation - over 100 kHz possible. Where as at high frequencies the inductive or capacitive
sensor output begins to distort
• When packed immune to dust, air, water where as capacitive sensor may get triggered by dust.
• Can measure zero speed
• Wide temperature range
• Highly repeatable operation
• Capable of measuring large current
The disadvantages of Hall effect sensors are:
• May be affected by external interfering magnetic field
• Large temperature drift
• Large offset voltage
• Signal can be blocked by ferrous metal
14. What is optical sensor?
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An optical sensor is a device that converts light rays into electronic signals. Similar to a photoresistor, it
measures the physical quantity of light and translates it into a form read by the instrument. Usually, the optical
sensor is part of a larger system integrating a measuring device, a source of light and the sensor itself. This is
generally connected to an electrical trigger, which reacts to a change in the signal within the light sensor.
15. Sketch the ideal phase voltage and current waveform of PMBLDC machine.
16. What are materials used for making Hall IC pallet?
ď‚· Indium-antinomy
ď‚· Gallium-arsenide
17. How the permanent magnet motors are named based on the wave shape of emf?
(i) 1800
polerarc BLPM SQW motor (ii)120”polearc BLPM SQW motor
18. Draw the magnetic equivalent circuit of 2 pole PMBLDC motor.
19. Name the position sensors that are used for PMBLDC motor.
Optical position sensor
Hall effect position sensor
20. Define intrinsic coercivity.
The strength of the magnetic field that is necessary to make the magnetic polarization (strength of
magnetization) to zero.
21. what is meant by self control?
Self control ensures that for all opearating points the armature and rotor fields move exactly at the same
speed.
22. what is meant by vector control?
PMSm are employed for variable speed applications. The process of controlling voltage and frequency to
get the desired speed and torque is known as vector control of PMSM
PART – B
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1. Derive the expression for Emf and torque of a PMBLDC motor. Draw the relevant waveforms.
2. Explain torque/ speed characteristic of PMBLDC motor.
3. Write a note on power controllers used in PMBLDC motor. (Nov/Dec 2007)
4. Explain the construction and working principle of PMBLDC motor. (Nov/Dec 2009)
5. Explain the closed loop control scheme of a PMBLDC motor drive with a suitable schematic diagram. 6. What are
the types of materials used in PMDC motors?
7. Why the PMBLDC motor is called electronically commutated motor?
The PMBL DC motor is also called electronically commutated motor because the phase windings of PLMBL DC
motor is energized by using power semiconductor switching circuits.here the power semiconductor switching
circuits act as a commutator.
8. Derive an expression for permeance coefficient for PMBLDC motor.
9. Discuss the use of Hall sensors for position sensing in PMBLDC motor.
10. Draw the B-H hysteresis loop of permanent magnet material.
UNIT V PERMANENT MAGNET SYNCHRONOUS MOTORS(PMSM) 9
Principle of operation–Ideal PMSM –EMF and Torque equations –Armature MMF –Synchronous Reactance –
Sine wave motor with practical windings -Phasor diagram –Torque/speed characteristics -Power controllers -
Converter Volt-ampere requirements–Applications
PART – A
1. What are features of permanent magnet synchronous motor?
Stator is made up of silicon steel stampings.stator slots carry a balanced 3phase armature winding, wound for
a specified even number of poles.The ends of the armature windings are connected to the terminals of the
motor.
Rotor is made up of forged steel with outward projected poles.The number of rotor poles must be same as
that of stator.These rotor poles carry field coils. They are suitably connected to form a field winding.The
ends of the field windings are connected to the two slip rings which are also mounted on to the same shaft.
2. What are advantages of load commutation?
3. What are the applications of PMSM?
4. What are features of closed loop speed control of loaded commuted Inverter fed synchronous motor drive?
5. What are the merits and demerits of PMSM?
Merits: It runs at a constant speed.
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No sliding contacts so it requires less maintenance
Demerits: Power factor of operation cannot be controlled as field current can‟t be controlled
6. Write the emf equation of PMSM.
7. What are assumptions made in derivation of emf for PMSM?
8. What is pulsated mode?
9. What is load commutation?
10. Clearly explain the difference between synchronous reluctance motor and PM synchronous motor.
11. What is meant by self motor?
12. How are PMBLDC motor and PMSM different? PMBLDC motor
13. What is meant by slot less motor?
14. State the two classifications of PM synchronous machines and the types in each.
15. Distinguish between self control and vector control PMSM.
16. State the differences between synchronous reluctance motor and PMSM.
17. What is meant by vector control?
PMSm are employed for variable speed applications. The process of controlling voltage and frequency to get the
desired speed and torque is known as vector control of PMSM
18. What is meant by synchronous reactance?
19. What is meant by field oriented control of PMSM?
20. Compare electromagnetic excitation with permanent magnet of PMSM.
PART – B
1. Explain the construction and working principle of operation of PMSM. Explain the microprocessor based control
of PMSM (Nov/Dec 2007)
2. Draw and explain the phasor diagram of PMSM (Apr/May 2010)
3. Derive torque and EMF equation of PMSM. (Nov/Dec 2007)
4. Compare BLPMDC motor and PMSM.
5. Derive the expression for synchronous reactance of PM synchronous motor.
6. Discuss about power controllers of PMSM.
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7. With necessary Phasor diagram and circle diagram, describe torque speed characteristics of PMSM.
8. Discuss PMBLDC and PMSM with respect to torque/ampere and KVA of converter/ kw of power to motor for 4
pole, 3 phase motor system.
9. Show the power output of PMBLDC motor is more than PMSM for the same size. 10. State the applications of
PMSM.
