VALLIAMMAI ENGINEERING COLLEGE SRM NAGAR, KATTANKULATHUR-603 203
DEPARTMENT OF ELECTRONICS AND INSTRUMENTATION ENGINEERING
M.E CONTROL AND INSTRUMENTATION ENGINEERING PX7203 Special Electrical Machines QUESTION BANK UNIT–I PERMANENT MAGNET BRUSHLESS D.C. MOTORS PART–A 1. Discuss the reason why adjustable speed drives are preferred over affixed speed motor? (BT2) 2. What is the structure of an adjustable speed drive system? (BT1) 3. List the advantages of PM machine? (BT1) 4. Classify PM machines? (BT3) 5. Compare brushless DC motor with P.M. commutator motor. (BT3) 6. What are the modes of operation of the square wave BLDC motor?(BT1) 7. Why the shape of the emf waveform of a BLDC is trapezoidal? (BT2) 8. Give the emf and torque equations of the square wave BLDC motor. (BT2) 9. Compare 120 degree and 180 degree operation of BLDC motor. (BT4) 10. Describe the function of sensors used with PMBLDC motors? (BT1) 11. MOSFET or IGBTs are used in inverters for PMBLDC motors. Justify (BT5) 12. Formulate the dynamic equations of the PMBLDC motor. (BT6) 13. List the relative merits and demerits of brush less DC motor drives? (BT1) 14. How the direction of rotation is reversed incase of PMBLDC motor. (BT3) 15. Classify various kinds of permanent magnets? (BT3) 16. Differentiate between square wave PMBL and sine wave PMBL motor. (BT4) 17. Express the torque of a sine wave PMBL motor in terms of number of start poles. (BT2) 18. Express induced emf/phase of the sine wave PMBL motor in terms of number of pole pairs. (BT2) 19. Recommend a commutator to get high reliability and discuss the reason. (BT5) 20. List out the uses of sensors in motors.(BT1) PART B 1. Derive equations for torque and EMF of the permanent magnet brushless DC motor. (BT2) 2. Sketch the structure of controller for permanent magnet brushless DC motor and explain the functions of various blocks. (BT4) 3. Describe the operation of the various rotor position sensors used in permanent magnet brushless DC Motor. (BT1)
Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
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Valliammai Engineering College
Dept. of EIE
4. Sketch and describe the torque–speed characteristics of a permanent magnet brushless DC motor. (BT2) 5. Develop an equation for the permeance coefficient of 2 pole permanent magnet brushless DC motor and draw its magnetic equivalent. (BT6) 6. Describe the operation of the various driving circuits used in permanent magnet brushless DC motor. (BT1) 7. Describe the working principle of electronic commutator of PMBLDC with neat sketch. (BT1) 8. C o m p a r e the constructional aspects of mechanical and electronic commutator of PMBLDC Motor. (BT5) 9. APMBLDC motor has torque constant 0.12Nm/A referred to DC supply. Calculate the motors no load speed when connected to 48V DC supply. Calculate the starting current and staring torque if armature resistance is0.15Ω/phaseand drop in controller transistor is 2V.(BT3) 10. Illustrate in detail, the operation of PMBLDC motor with 180 magnet arcs and 120 square wave phase currents. (BT3) PART C 1. Analyze the various kinds of permanent magnet materials with the B-H loop Characteristics in detail. 2. A three phase, four pole BLPM motor 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 magnetic flux is 1.8 mwb. Estimate the open circuit phase emf Eg at 3000 rpm. 3. Analyze the different types of Sensors used in find the shaft rotor position in PMBLDC motors. 4. Develop the pemeance coefficient with the knowledge of the magnetic circuit analysis. UNIT–II PERMANENT MAGNET SYNCHRONOUS MOTORS PART–A 1. Compare PMSM and PMBLDC motors. (BT4) 2. Give the expression for torque and emf of a PMSM motor. (BT2) 3. What is meant by field oriented control of PMSM? (BT1) 4. List out the inherent advantages of variable reluctance motor? (BT1) 5. List out the applications of PMBLDC and PMSM motors? (BT1) 6. What are the features of permanent magnet synchronous motor? (BT1) 7. Differentiate between synchronous motor and PMSM (BT4) 8. Summarize the assumptions made in derivation of emf equation for PMSM? (BT5) 9. Write down the expressions for power input and Torque of a PMSM?(BT2) 10. What are the features of closed- loop speed control of load commutated inverter fed Synchronous motor drive? (BT1) 11. Write down the emf expressions of PMSM? (BT2) 12. What is load commutation? (BT1) 13. Recommend a machine which has very little difference between direct axis and quadrature Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
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Valliammai Engineering College
Dept. of EIE
axis inductances for ship propulsion. (BT5) 14. Classify Permanent Magnet Synchronous Motor? (BT3) 15. Classify the rotors of permanent magnet synchronous motor?(BT3) 16. Distinguish between self-control and vector control of PMSM? (BT2) 17. Discuss the benefits of load commutation in permanent magnet synchronous motor. (BT2) 18. Deduce the condition for magnitude of stator current in PMSM to achieve demagnetization. (BT5) 19. Draw the torque speed characteristics of PMSM? (BT4) 20. Formulate the equations for the self and synchronous reactance of PMSM? (BT6) PART B 1. Develop expressions for the EMF and torque of BLPM Sine wave motor. (BT6) 2. A three phase 16 pole synchronous motor has a star connected winding with 144 slots and 10 conductors per slot. The flux per pole is 0.03 wb, sinusoidally distributed and the speed is 375 rpm. Calculate the frequency, phase and line emf. Assume full pitched coil. (BT3) 3. Describe the vector control of permanent magnet synchronous motor with neat diagram. (BT1) 4. With neat sketch, discuss the torque–speed characteristics of PMSM. (BT2) 5. Compare the constructional features of PMBLDC and PMSM? (BT5) 6. Draw and explain the phasor diagram of permanent magnet synchronous motor.(BT4) 7. Illustrate with neat sketch, the steady state phasor diagram of synchronous reluctance motor. (BT3) 8. Discuss the construction and working principle of synchronous reluctance motor with neat sketch. (BT2) 9. Describe in detail, the speed-torque and torque-angle characteristics of synchronous reluctance motors. (BT1) 10. Write a detailed technical description on the following (i) axial type synchronous reluctance motor (ii) radial type synchronous reluctance motor. (BT1) PART C 1. 2. 3. 4.
Design the step by step procedure for digital controllers of PMSM drives. Analyze in detail about the different power controllers used in PMSM drives. Design and draw the circle diagram of synchronous reluctance motors. Develop the voltage and torque equations of synchronous reluctance motor. UNIT–III SWITCHED RELUCTANCE MOTOR PART-A
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What is basic principle of operation of switched reluctance motor? (BT1) List out the advantages of Switched Reluctance motor? (BT1) D i f f e r e n t i a t e Switched Reluctance motor and variable reluctance stepper motor? (BT2) Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
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Valliammai Engineering College
Dept. of EIE
4. List out the disadvantages of a Switched Reluctance motor? (BT1) 5. Distinguish between co-energy and field energy (BT2) 6. What are the applications of Switched Reluctance motor? (BT3) 7. Write the expression between the speed and fundamental switching frequency. (BT2) 8. What is co-energy? (BT1) 9. Formulate the expression for torque of a Switched Reluctance motor.(BT6) 10. Write the classification of power controllers used for Switched Reluctance motor?(BT4) 11. Is rotor position sensor essential for the operation of Switched Reluctance motor? Justify (BT5) 12. What are the classifications of current control techniques of SRM? (BT4) 13. What is meant by energy ratio? (BT1) 14. What is phase winding of SRM? (BT1) 15. Calculate the step angle of 5 phase SRM and commutation frequency in each phase for the speed of 6000 rpm. It has 10 stator poles and 4 rotor poles. (BT3) 16. Compare Switched Reluctance Motor and Stepper Motor. (BT4) 17. In Which type of application the chopping mode control of SRM is used? (BT3) 18. Discuss the merits of classic converter or power controller in SRM?(BT2) 19. C l a s s i f y power converters used for the control of switched reluctance motor? (BT3) 20. Is Switched Reluctance machines popular in adjustable speed drives? Support your answer with reason. (BT5) PART B 1. Explain the construction and working of Switched Reluctance motor with neat sketch? (BT4) 2. With a block diagram explain the importance of closed loop control of Switched Reluctance motor. (BT5) 3. Describe the Hysteresis type and PWM type current regulator for one phase of Switched Reluctance motor. (BT1) 4. (i)Explain in detail about microprocessor based control of Switched Reluctance motor.(BT1) (ii) Explain how the effect of saturation improves the efficiency in SRM. 5. Discuss the various power controller circuits to Switched Reluctance motor and explain the operation of any one scheme with suitable circuit diagram. (BT2) 6. Discuss the various operating modes of Switched Reluctance motor. (BT2) 7. Formulate the voltage and torque equation of Switched Reluctance motor. (BT6) 8. Draw and explain torque–speed characteristics of Switched Reluctance motor. (BT1) 9. Compare the sensor and sensor less scheme of operation. Illustrate the principle of operation of SRM sensor less scheme with block diagram. (BT4) 10. A 3 phase SRM having 6 stator poles and 4 rotor poles has a stator pole arc of 30̊ and rotor pole arc of 32̊. It has aligned inductance 10.7 mH and unaligned inductance 1.5mH and saturation effect can be neglected. Calculate the maximum energy conversion in one stroke with current limited to 7A. Determine the average torque corresponding to this energy conversion. (BT3)
Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
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Valliammai Engineering College
1. 2. 3. 4.
Dept. of EIE
PART C Analyze the various converter topologies for a 3 phase Switched Reluctance motor with their merits and demerits. Analyze the role of computers in the control of switched reluctance motor. Analyze the effect of saturation on energy conversion in SRM for (a) linear or unsaturated condition, (b) Practical case and (c) idealized case with extreme saturation. With the derivation of the relevant equation, evaluate the static torque production in SRM?
What is a Stepper motor? (BT1) List out the advantages of Stepper motor? (BT1) Classify stepper motor based on its construction?(BT3) What are Step Angle of stepper motor and Resolution of stepper motor?(BT1) Compare Holding torque and Detent torque of stepper motor. (BT4) Differentiate Pull –in and pull out torque of stepper motor. (BT2) What are Slewing frequency and stepping frequency of stepper motor.(BT1) Compare Maximum starting torque and maximum starting frequency of stepper motor. (BT4) 9. What is rest position or equilibrium position of stepper motor?(BT1) 10. How micro stepping is achieved in stepper motor? (BT4) 11. Evaluate the step angle of a four phase stepper motor with 12 stator teeth and 3 rotor teeth. (BT5) 12. What are the classifications of drive system of stepping motor? (BT3) 13. Express the step number and the step angle in a stepper motor?(BT2) 14. Evaluate the resolution of a stepper motor having a step angle of 1.8°. (BT5) 15. Formulate the equation for speed of stepper motor. (BT6) 16. List out the different modes of excitation used in variable reluctance stepping motors? (BT1) 17. Describe the limitations of open loop operation of stepper motors. (BT2) 18. Classify the modes of excitation of stepper motor? (BT3) 19. Compare closed loop control and open loop control in stepper motor. (BT4) 20. Write the expression of torque constant of a stepper motor. (BT2) PART B 1. Explain w i t h n e a t s k e t c h the construction and principle of operation of Variable Reluctance Stepping Motor. (BT4) 2. Discuss the construction and operation of permanent magnet Stepping motor with neat diagram? (BT2) 3. Explain the construction and working principle of hybrid Stepping motor? (BT4)
Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
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Valliammai Engineering College
Dept. of EIE
4. Discuss the static and dynamic characteristics of stepper motor with neat sketch? (BT2) 5. D e s c r i b e the need of closed loop control of stepper motor? List out the drawbacks of open loop system?(BT1) 6. Classify the drive system of a stepping motor and Illustrate the operation of any three types of drive circuits with neat diagram. (BT3) 7. Formulate the equation for stepping rate of stepper motor using linear and nonlinear analysis. (BT6) 8. Formulate the equation for mechanical work done from the concept of torque production in variable reluctance stepping motor. (BT6) 9. Calculate the motor torque required to accelerate an initial load of 2 X 10-4 Kg m2 from 500 Hz to 1500 Hz in 50 ms. The frictional torque is 0.03 N-m and step angle is 1.18 deg. (BT5) 10. Describe the closed loop control of stepper motor with neat block diagram. (BT1) PART C 1. 2. 3. 4.
Analyze the theory of Torque prediction in Stepper motor. Design the dual voltage driver circuit for two phase on drive of a four phase stepper motor . Analyze the different types of power drive circuits used for Stepper motor. Design the Variable reluctance stepper motor with step by step procedure. UNIT-V OTHER SPECIAL MACHINES PARTA
1. Which type of single-phase induction motors is employed in high-speed fractional KW applications? (BT1) 2. Differentiate A.C series motor and D.C series motor. (BT2) 3. What is the specialty of hysteresis motor? (BT1) 4. List out the various methods available for making a single-phase motor self-starting? (BT1) 5. Formulate the Torque equation of universal motor. (BT6) 6. Classify single phase motor based on its construction? (BT3) 7. Describe the principle of working of a hysteresis motor? (BT1) 8. List out applications of Linear Induction motor.(BT1) 9. Explain the necessity of having laminated yoke in an ac series motor?(BT4) 10. How can the speed of a linear induction motor be controlled?(BT4) 11. Does the starting torque of a hysteresis motor have the hysteresis torque as the only component? Justify your answer. (BT5) 12. Formulate the relation between AC and DC speeds of universal motor. (BT6) 13. Classify single phase series commutator motor based on its construction. (BT3) 14. Express the Thrust force of LIM in terms of synchronous speed. (BT2) 15. Compare rotating motor and linear motor. (BT4) 16. Draw the phasor diagram of a.c. series motor. (BT1) Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
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Valliammai Engineering College
Dept. of EIE
17. How commutation effect is reduced in ac series motor. (BT2) 18. Discuss the modifications to be done while designing ac series motor? (BT2) 19. Dc series motor cannot be operated satisfactorily in ac supply. Justify your answer (BT5) 20. Mention the applications of Hysteresis motor. (BT3) PART B 1. Discuss the construction and working principle of hysteresis motor with neat diagram. (BT2) 2. Describe the construction and working principle of AC series motor with neat sketch.(BT1) 3. Describe the principle of operation and applications of repulsion motor. (BT1) 4. Explain Hysteresis motor with neat sketches the principle of operation and the application. (BT4) 5. A100W, 2pole, 50Hz, 230V single phase series motor with salient poles has a total resistance of 15Ω leakage resistance of 40Ω, mutual resistance of 80Ω (in d-axis) and 50Ω (in q-axis). If the stray power losses are 20 watts, evaluate the value of current, speed and power factor of the motor at full-load. (BT5) 6. What is the constructional difference between dc series and 1 phase series motor? Why should a series motor never be operated on no load? List the common application of 1 phase series motor. (BT2) 7. Mention the problems usually encountered when a dc series motor is operated on ac. What design modifications are to be incorporated for its satisfactory operation on ac? Compare the speed for dc and ac supply. (BT4) 8. Formulate the torque equation of ac series motor. (BT6) 9. Draw the phasor diagram of a single phase series motor and show that its performance characteristics can be predicted from a circle diagram. Sketch the typical performance characteristics against current. What are the special design features when compared to a series motor? (BT1) 10. Describe the construction of a synchronous hysteresis motor and show that it develops a running torque both at synchronous and a synchronous speed of rotor. (BT3) PART C 1. 2. 3. 4.
Analyze the control techniques used for hysteresis motor in detail. Design the step by step procedure for a.c. series motor. Analyze in detail about power controllers used in linear motors. Design the driver circuits used in repulsion motor with the help of power semiconductor devices.
Prepared by Dr.K.AYYAR, Assistant Professor (Selection Grade)
