The Switched reluctance Motor (SRM) is an old member of the
Electric Machines Family. Its simple structure, ruggedness and
inexpensive manufacturing capability make it more attractive for Industrial
applications. However these merits are overshadowed by its inherent high
torque ripple, acoustic noise and difficulty to control.
This thesis presents a space vector modulation for SRM drive. The SRM is
fed by a three-phase asymmetrical power converter having three legs,
each of which consists of two IGBTs and two free-wheeling diodes. During
conduction periods, the active IGBTs apply positive source voltage to the
stator windings to drive positive currents into the phase windings. During
free-wheeling periods, negative voltage is applied to the windings and the
stored energy is returned to the power DC source through the diodes.
Switched-reluctance (SR) motors with advent of compact but powerful
solid-state power devices and ICs.
Now, with a new emphasis on energy efficiency, switched-reluctance
motors may be ready to take a more prominent role in appliances, industrial
equipment, and even off-road gear
The dc machine has been the primary choice for the servo applications,
because of their excellent drive performance and low initial cost.
The advantages of the ac machine to the dc machine are in the areas of
The low cost, ruggedness and almost maintenance free operation of the
induction machines have made it the workhorse of the industry.
The different types of synchronous motors are used because of the high
level of accuracy that can be achieved in speed control.
The simplicity in both motor construction and power converter requirement
made the switched reluctance motor (SRM) an attractive alternative to the
induction motor and the PM motors in adjustable speed drive applications.
A quest for energy efficiency has fostered development of switched
reluctance motors that are inherently simple and can supply variable
BASIC CONSTRUCTION OF AN SRM
The SRM is a doubly-salient, singly-excited machine with independent
windings of the stator.
Its stator structure is same as PM motor, but the rotor is simpler having no
permanent magnet on it
Stator windings on diametrically opposite poles are connected in series or
parallel to form one phase of the motor.
The configurations with higher number of stator/rotor pole combinations
have less torque ripple.
A switched-reluctance motor works in a way that is somewhat analogous
with a stepper motor. An SR-motor rotor consists of laminated-steel
It carries no windings, magnets, or other features. The protuberances are
strongly magnetically permeable. Areas surrounding them are weakly
permeable by virtue of slots cut into them.
The reluctance motor is an electric motor in
which torque is produced by the tendency of
its moveable part to move to a position
where the inductance of the excited winding
The reluctance motor is a type of
synchronous machine. It has wound field
coils of a DC motor for its stator windings
and has no coils or magnets on its rotor.
Figure shows its typical structure. It can be
seen that both the stator and rotor have
salient poles; hence, the machine is a doubly
CONTROL METHODS OF SWITCHED RELUCTANCE MOTOR
Voltage controlled drives.
Current controlled drives.
T/A or efficiency Maximization.
Torque ripple minimization.
Acoustic Noise Minimization.
Sensor less controllers.
PARAMETERS OF CONTROLLING
Appropriate positioning of the phase excitation
pulses is the key in obtaining effective performance.
θon, θdwel and Iph
Control parameters determine torque, efficiency
and other performance parameters.
SRM provides an attractive solution
for a number
of applications, such as
Fluid Pumps, vacuum blowers
Process control industries
Electromechanical brake system
Electric power steering
Fuel pump operation
A reduction of about 15~25 dB noise
level is achieved with the low-noise
The drive system with optimally-
designed SRM has 35% wider speed
range with 6~20% lower torque-dip.
Position and speed sensor less SRM drive is realized using sliding-mode
Online adaptation with sensor less operation.
Indirect estimation shows the promise of sophisticated control (torque-
ripple minimization) realization with sensor less operation
CONVERTER means Which converts AC-DC or
Which converts ac-dc is known as rectifier
And dc-ac is known as inverter
The converter operation is depend on firing angle
If α<90 it operates as rectifier and α>90 it operates
Converter consisting of IGBTs and diodes and
other power electronic equipments
DIFFERENT TYPES OF
AC to DC converters
AC voltage controllers (or)
Choppers (or)DC to DC converters
Inverters(or)DC to AC converters
• The SVPWM is considered as a better technique of PWM implementation as it has
advantages over SPWM in terms of good utilization of dc bus voltage, reduced switching
frequency and low current ripple.
• Space Vector Modulation (SVM) for VSI is based on the representation of the phase
quantities as vectors in a two-dimensional ( α,β ) plane.
• Switching States (Three-Phase)
• Eight switching states
Space Vector Modulation
• Space Vector Diagram
• Active vectors: to
(stationary, not rotating)
• Zero vector:
• Six sectors: I to IV
Space Vector Modulation
CURRENT-CONTROL AND TORQUE AMPLIFICATION OF 6 POLE
STATOR 4 POLE ROTOR OF SWITCHED RELUCTANCE
This project presents a current-controlled 60-kW 6/4 SRM drive
using the SRM specific model based on measured magnetization
The SRM is fed by a three-phase asymmetrical power converter
having three legs, each of which consists of two IGBTs and two
During conduction periods, the active IGBTs apply positive source
voltage to the stator windings to drive positive currents into the
During free-wheeling periods, negative voltage is applied to the
windings and the stored energy is returned to the power DC source
through the diodes.
The fall time of the currents in motor windings can be thus reduced.
By using a position sensor attached to the rotor, the turn-on and
turn-off angles of the motor phases can be accurately imposed.
The most suitable and flexible Switched Reluctance Motor
converter is the asymmetric type converter. This converter
has the ability of fault tolerance; continuous operation with
reduced power output of the motor drive can also be obtained
in case of failure of one winding.
By comparing different type converter topologies; it is found
that the asymmetric converter type (With MOSFET) is suitable
for very high speed operation of SRM drive because of the
quick rise and fall times of current and moreover it give
negligible shoot through faults. But, for medium speed
operation at high power,
IGBTs power switches are preferred due to low conduction
losses and due to their high input impedance. In future SVM
analysis to be conducted for all these converters to analysis to
performance of SRM to reduce the torque ripple.
[I] Samia M. Mahmoud, Mohsen Z. EI-Sherif, "Studying Different Types of Power Converters Fed
Switched Reluctance Motor," International Journal of Electronics and Electrical Engineering, vol. I,
no. 4, pp. 281-290 December 2013.
 T. Wichert, "Design and construction modifications of switched reluctance machines," Ph.D.
thesis, Warsaw University of Technology, 2008.
 Y Hasegawa, K. Nakamura, and O. Ichinokura, "Development of a switched reluctance motor
made of permendur," in Proc. 2nd Int. Symp. on Advanced Magnetic Materials and Applications,
Journal of Physics, 2011.
 M. T. Lamchich, Torque Control, InTech Publisher, February 10,2011, ch. 8.
 R. D. Doncker, D. W. J. Pulle, and A. Veltman, Advanced Electrical Drives: Analysis, Modeling,
Control, Springer Press, 2011, ch. 10.
 E. S. Elwakil and M. K. Darwish, "Critical review of converter topologies for switched reluctance
motor drives," International Review of Electrical Engineering, vol. 2, no. I, January-February 20 I I.