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Special Electrical Machines book. Read 6 reviews from the world's largest community for readers. This book brings together in a single volume the theory. Subject: SPECIAL ELECTRICAL MACHINES. Class.: IV Year EEE being prepared by me and it meets the knowledge requirement of the university curriculum. [PDF] EE Special Electrical Machines (SPE) Books, Lecture Notes, 2marks with answers, Important Part B 16marks Questions, Question Bank & Syllabus.
Explain in detail the vector control of permanent magnet synchronous motor. With neat sketch, discuss the torque speed characteristics of PMSM. Draw and explain the phasor diagram of permanent magnet synchronous motor.
With a neat diagram, explain the operation of power of controller for perma nent magnet synchronous motor. Explain circle diagram of permanent magnet synchronous motor. Discuss the different rotor configurations of PM synchronous machines. Write a detailed technical note on the following i vector control of PMSM ii microprocessor based control Valliammai Engineering College. What is basic principle of operation of switched reluctance motor?
The switched reluctance motor is a doubly salient, singly excited motor.
This means that it has salient poles on both the rotor and the stator, but only one member usually the stator carries windings. The rotor has no windings; magnet is or cage windings but is built up from stacks of salient pole laminations.
The basic principle operation of SRM is Variable reluctance. What are the advantages of Switched Reluctance motor? Rotor is simple and it tends to have a low inertia, The stator is simple to wind, In most applications the bulk of the losses appear on the stator, which is relatively easy to cool, Due to the absence of magnet the maximum permissible rotor temperature may be higher than in PM motors, Under fault conditions the open circuit voltage and short circuit current are zero or varying small, Extreme by high speeds are possible 3.
What is the difference between Switched Reluctance motor and variable reluctance stepper motor? Switched Reluctance motor Variable reluctance stepper motor Conduction angle for phase current is controlled Stepper motor is usually fed with a square and synchronized with the rotor position, usually by wave of phase current without rotor position means of a shaft position sensor feedback.
The SRM is designed for efficient power It is usually designed as a torque motor with a conversion at high speed limited speed. What are the disadvantages of a Switched Reluctance motor? Distinguish between co-energy and field energy Co-energy Field energy i. What are the applications of Switched Reluctance motor? Precision position control system for Robotics, Low power servo motor 7.
Write the relations between the speed and fundamental switching frequency.
The no of stator poles usually exceeds the no of rotor poles. What is co-energy? In the i curve of a motor, the area between the curve and horizontal i axis is the co-energy W and the other part is the stored field energy W f. Give the expression for torque of a Switched Reluctance motor. What are the types of power controllers used for Switched Reluctance motor? Why rotor position sensor is essential for the operation of Switched Reluctance motor?
It is normally necessary to use a rotor position sensor for communication 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. What are the two types of current control techniques? Hysteresis type control, PWM type control What is meant by energy ratio? As the stored energy R is not wasted as a loss but it is feedback to the source through feedback diodes.
What is phase winding of SRM? Stator poles carrying field coils. The field coils of opposite poles are connected in series such that mmfs are additive and they are called Phase winding of Switched Reluctance motor. What is Hysteresis current control?
This type of current controller maintains a more or less constant throughout the conduction period in each phase. This controller is called hysteresis type controller.
Chopping mode of operation of Switched Reluctance motor? In this mode, also called low speed mode, each phase winding gets excited for a period which is sufficiently long. Single pulse mode of operation of Switched Reluctance motor? In this mode, also called high speed mode, the current rise is within limits during the small time interval of each phase excitation.
What are the merits of classic converter or power controller in SRM? Control of each phase is completely independent of the other phases; the energy from the off going phase is feedback to the source, which results in useful utilization of the energy. What are the different power converters used for the control of switched reluctance motor? Why SR machines popular in adjustable speed drives? Rotor is simple and it tends to have a low inertia, The stator is simple to wind, In most applications the bulk of the losses appear on the stator, which is relatively easy to cool, Due to the absence of magnet the maximum permissible rotor temperature may be higher than in PM motors, Under fault conditions the open circuit voltage and short circuit current are zero or varying small, Extreme by high speeds are possible PART B 1.
Explain the construction and working of Switched Reluctance motor? With a block diagram explain the importance of closed loop control of Switched Reluctance motor. Describe the various power controller circuits to Switched Reluctance motor and explain the operation of any one scheme with suitable circuit diagram. Describe the various operating modes of Switched Reluctance motor.
Derive the voltage and torque equation of Switched Reluctance motor. Draw and explain torque speed characteristics of Switched Reluctance motor. Discuss the advantages and disadvantages of Switched Reluctance motor. Discuss in detail the frequency of variation of the inductance of each phase winding of Switched Reluctance Motor. Valliammai Engineering College.
Stepper motor? Stepper motor is a motor which rotates step by step and not continuous rotation.
When the stator is excited using a DC supply the rotor poles align with the stator poles in opposition such that reluctance is less. What are the advantages of Stepper motor? No feedback is normally required for either position control or speed control, Positional control is non cumulative, Stepping motor are compatible with modern digital equipment 3. Mention the different types of stepper motor? Variable Reluctance stepper motor Single stack, Multi stack , Permanent magnet stepper motor, Hybrid stepper motor, Outer rotor stepper motor 4.
Step Angle of stepper motor and Resolution of stepper motor? A stepping motor rotates through a fixed angle for every pulse.
The rated value of this angle is called the step angle and expressed in degrees. Resolution is defined as the accuracy of positioning of the rotor pole at a particular step angle with respect to stator pole. Holding torque and Detent torque of stepper motor. Holding torque is defined as the maximum static torque that can be applied to the shaft of an excited motor without causing continuous rotation.
Detent torque is defined as the maximum static torque that can be applied to the shaft of an unexcited motor without causing continuous rotation. Pull in and pull out torque of stepper motor.
Pull in torque is called the starting characteristics and refer to the range of frictional load torque at which the motor can start and stop without loosing steps for various frequencies in a pulse strain.
Pull out torque is called the slewing characteristics. After the test, motor is started by a specified driver in the specified excitation mode in the self starting range; the pulse frequency is gradually increased; the motor will eventually run out of synchronism. The relation between the frictional load torque and the minimum pulse frequency with which the motor can synchronize is called pull out characteristics.
Slewing frequency and stepping frequency of stepper motor. May 13 Slewing frequency is defined as the maximum frequency stepping rate at which the loaded motor can run without losing steps is alternatively called the maximum slewing frequency.
The speed of rotation of a stepping motor is given in terms of the number of steps per second and the term stepping rate is often used to indicate speed. Maximum starting torque and maximum starting frequency of stepper motor. Maximum starting torque is alternatively called as maximum pull in torque and is defined as the maximum frictional load with which the motor can start and synchronize with the pulse train of frequency as low as 10 Hz.
Maximum starting frequency is the maximum control frequency at which the unloaded motor can start and stop without losing steps. What is rest position or equilibrium position of stepper motor? It is defined as the position at which as excited motor comes to rest at no load.
What is micro stepping and how is it achieved? It is possible to subdivide on natural step into many small steps by means of electronics. This method is known as mini step or micro step. What is the effect of magnetic saturation in stepper motor? The efficiency is improved, and the losses are reduced.
What are the classifications of drive system of stepping motor? Open loop system, closed loop system What is the relationship between the step number and the step angle in a stepper motor? What is Cyclonome? A stepping motor manufactured by Sigma instruments Inc. What are the various bipolar drives used for stepper motor? What are the different modes of excitation used in variable reluctance stepping motors?
Mention the limitations of open loop operation of stepper motors. The open loop drive is attractive and widely accepted in applications of speed and position controls. However the performance of stepper motor driven in open loop mode may fail to follow a pulse command when the frequency of the pulse train is too high or the inertial load is too heavy.
What are the different modes of excitation? Single phase excitation, two phase excitation, Half step mode, Mini-step drive.
Compare closed loop control and open loop control in stepper motor. Closed loop control is more accurate, oscillatory motions are avoided for certain speed ranges, Speed remains constant for high inertial load, follows the input pulses at stepping frequency are some of the advantages over open loop control.
But it is costly and complex. Define torque constant of a stepper motor. The torque constant of the stepper motor is defined as the initial slope of the torque current curve of the stepper motor. Explain the construction and principle of operation of 1-phase and 2-phase of Variable Reluctance Stepping Motor. Explain the construction and operation of permanent magnet Stepping motor? Explain the construction and operation of hybrid Stepping motor?
Discuss the static and dynamic characteristics of stepper motor with neat sketch? What are the drawbacks of open loop system? What is the need of closed loop control of stepper motor? Explain in detail the linear and non linear analysis of stepper motor? Explain in detail the drive system of a stepping motor?
Explain in detail the multi stack Variable Reluctance Stepping motor? Explain the concept of torque production in variable reluctance stepping motor. Problem on torque and stepping angle of stepper motor. What type of single-phase induction motors is employed in high-speed fractional KW applications? Single phase A. C series motor. Give the main difference in construction of an A.
C series motor and a D. The entire iron structure of the field cores and yoke are laminated to reduce the eddy current loss. Number of turns in the field winding is reduced to have large reactance and higher power factor.
C series motors are provided with commutating poles. What is the specialty of hysteresis motor? The rotor has no winding 4. What are the various methods available for making a single-phase motor self-starting? C series motor 6. Classification of single phase motor?
What is the principle of working of a hysteresis motor? This is the synchronous motor magnetic locking which does not require any dc excitation to the rotor and it uses non projected poles. List the applications of Linear Induction motor. Magnetic Levitation, linear propulsion, and linear actuators. They have also been used for pumping liquid metals 9.
What is the necessity of having laminated yoke in an ac series motor? Yoke and the pole and armature cores of ac series motors are laminated so that eddy current losses are reduced and so efficiency is improved and heating is reduced. How can the speed of a linear induction motor be controlled? The speed of a linear induction motor can be controlled by varying both frequency and voltage simultaneously Does the starting torque of a hysteresis motor have the hysteresis torque as the only component?
No, eddy current torque in addition to hysteresis torque. What is the principle of working of a Linear induction motor? Whenever there occurs a relative motion between the field and the short circuit conductors, currents are induced in them which results in electromagnetic forces and under the influence of these forces, according to Lenzs law, the conductors try to move in such a way as to eliminate the induced currents. What are parameters does the LIM speed depends upon?
LIM synchronous speed does not depend upon number of poles but on pole pitch and supply frequency. Write the expression of Thrust force of LIM. Mention the advantages and disadvantages of LIM. Low initial cost, simplicity, No overheating of rotor. High magnetizing current results in poor efficiency and low pf. Draw the phasor diagram of a. How commutation effect is reduced in ac series motor.
Commutation effect is reduced by compensating winding Conductively and inductively and interpoles. What are the modifications done while designing ac series motor? The magnetic circuit is laminated to reduce eddy current loss, the field no.
Mention some reasons why dc series motor cannot be operated satisfactorily in ac supply. Ripple in torque, increase in eddy current, poor starting torque, develops rotational emf which decreases efficiency of the motor.
Mention the characteristics and application of Hysteresis motor. Because of noiseless operation and ability to drive high inertia loads, hysteresis motors are particularly well suited to drive timing devices, electric clocks, tape-decks, turn tables and other precision audio equipment.
What is the principle and working of hysteresis motor? What is the principle and working of AC series motor? Explain 3. Explain the principle of operation and applications of repulsion motor and hysteresis motor. Explain Hysteresis motor with neat sketches the principle of operation and the application.
A W , 2pole ,50Hz, V single phase series motor with salient poles has a total resistance of 15 leakage resistance of 40, mutule resistance of 80 in d-axis and 50 in q-axis. If the stray power losses are 20watts, calculate the current , speed and power factor of the motor at full-load.
What is the constructional difference between dc series and 1phase series motor? Why should a series motor never be operated on no load? List the common application of 1 phase series motor 7. Mention the problems usually encountered when a dc series motor is operated on ac.
What design modification are to be incorporated for its satisfactory operation on ac?
Compare the speed for dc and ac. Explain commutation in ac series motor and Derive the torque equation of ac series motor. Oct 14, Vikasangel marked it as to-read Shelves: This review has been hidden because it contains spoilers.
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