This presentation contains the details about Phasor diagram and characteristics of Synchronous Reluctance motor

1. Contents:
 Phasor diagram
 Torque – Speed characteristics
 Comparison of Axial and Radial flux Motors
 Designing Parameters
 References
Synchronous Reluctance Motor – Phasor diagram and
Characteristics
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

2. Phasor Diagram
The synchronous reluctance machine is considered as a balanced three phase circuit, it is
sufficient to draw the phasor diagram for only one phase.
The basic voltage equation neglecting the effect of resistance is
V = E – j IsdXsd – j Isq
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

3. Where ,
V is the Supply Voltage Is is the stator current
 E is the excitation emf
δ is the load angle
ɸ is the phase angle
Xsd and Xsq are the synchronous reactance of direct and quadrature
axis
Isd and Isq are the direct and quadrature axis current
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

4. Torque Speed Characteristics
The torque speed characteristic of synchronous reluctance motor
is shown in fig. The motor starts at anywhere from 300 to 400
percent of its full load torque (depending on the rotor position of the
unsymmetrical rotor with respect to the field winding) as a two
phase motor.
As a result of the magnetic rotating field created by a starting and
running winding displaced 90° in both space and time. At about ¾th
of the synchronous speed a centrifugal switch opens the starting
winding and the motor continues to develop a single phase torque
produced by its running winding only.
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

5. As it approaches synchronous speed, the reluctance torque is sufficient to pull the
rotor into synchronism with the pulsating single phase field.
The motor operates at constant speed up to a little over 20% of its full load torque.
 If it is loaded beyond the value of pull out torque, it will continue to operate as a
single phase induction motor up to 500% of its rated speed.
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

6. Comparison between axial airgap synchronous reluctance
motor and radial airgap synchronous reluctance motor.
Radial airgap motors Axial airgap motors
High speed applications Low speed applications
Lamination is radial Lamination is axial
More mechanical strength Less mechanical strength
The radially laminated rotor has
the best potential for economic
production
The axially laminated rotor in
general gives the best
performance, but the mass
production difficulties with
folding and assembling the
laminations make its adoption by
industry unlikely.
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

7. Design parameters of a synchronous
reluctance motor.
• High output power capability
• Ability of the rotor to withstand high speeds
• Negligible zero-torque spinning losses
• High reliability
• High efficiency
• Low cost
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics

8. REFERENCES
S.No Books / Web Sources
1. K.Venkataratnam, ‘Special Electrical Machines’, Universities Press (India) Private Limited, 2008
2. T.J.E. Miller, ‘Brushless Permanent Magnet and Reluctance Motor Drives’, Clarendon Press,Oxford, 1989.
3. T. Kenjo, ‘Stepping Motors and Their Microprocessor Controls’, Clarendon Press London, 1984.
4.
R.Krishnan, ‘Switched Reluctance Motor Drives – Modeling, Simulation, Analysis, Design andApplication’, CRC
Press, New York, 2001.
5. P.P. Aearnley, ‘Stepping Motors – A Guide to Motor Theory and Practice’, Peter Perengrinus ,London, 1982.
6. T. Kenjo and S. Nagamori, ‘Permanent Magnet and Brushless DC Motors’, Clarendon Press, London, 1988.
7. K.Dhayalini, “Special Electrical Machines,” Anuradha Publications, 2017.
8. Google and Wikipedia
Kongunadu College of Engineering & Technology Synchronous Reluctance Motor - Phasor diagram and Characteristics