GROUP MEMBERS
SHUJAT ALI (18B-037-PE)
ZAIN-UL-ABDIN (18B-012-PE)
ZARGHAM MUGHAL (18B-038-PE)
MUHAMMAD IRTIZA BARI (18B-013-PE)
SWITCH RELUCTANCE MOTOR
CONSTRUCTION, WORKING AND PERFORMANCE ANALYSIS
CONSTRUCTION OF SWITCH
RELUCTANCE MOTOR
VARIABLE RELUCTANCE MOTOR OR SWITCHED RELUCTANCE MOTOR HAS TWO
DIFFERENT CONSTRUCTIONS: SINGLY SALIENT CONSTRUCTION AND DOUBLY
SALIENT CONSTRUCTION. STATOR AND ROTOR MAGNETIC CIRCUITS ARE
LAMINATED TO REDUCE THE CORE LOSSES IN BOTH TYPE OF SRM.
SINGLY SALIENT CONSTRUCTION:
A SINGLY SALIENT CONSTRUCTION SRM COMPRISES OF A NONSALIENT STATOR AND A SALIENT TWO POLE ROTOR. THE ROTOR
DO NOT HAVE ANY WINDING WOUND OVER IT BUT THE STATOR
HAVE TWO PHASE WINDING
It should be noted that, in actual SRM the number of phase winding on stator
may be more than two. Since the rotor is of salient construction, the
inductance of stator phase winding varies with the rotor position. The
inductance is minimum when the rotor axis and stator phase winding axis
coincides whereas it is maximum when both the axis are in quadrature.
DOUBLY SALIENT
CONSTRUCTION
UNLIKE SINGLY SALIENT TYPE, THE STATOR OF DOUBLY SALIENT
SWITCHED RELUCTANCE MOTOR IS OF SALIENT CONSTRUCTION AND
CONSISTS OF FOUR POLES AS SHOWN IN FIGURE BELOW. THE ROTOR
DO NOT CARRY ANY WINDING AND IS OF SALIENT CONSTRUCTION BUT
HAVE TWO POLES. THUS THIS TYPE OF SRM IS A HETRO-POLAR MOTOR
WHERE THE NUMBERS OF STATOR AND ROTOR POLES ARE NOT SAME.
• THE STATOR PHASE WINDINGS ARE
CONCENTRATED WINDING. THESE
CONCENTRATED WINDINGS ON
RADIALLY OPPOSITE POLES ARE EITHER
CONNECTED IN SERIES OR PARALLEL TO
RESULT INTO TWO PHASE WINDING
ON STATOR.
• A DOUBLY SALIENT TYPE SWITCHED
RELUCTANCE MOTOR OR VARIABLE
RELUCTANCE MOTOR PRODUCES MORE
TORQUE AS COMPARED TO SINGLY
SALIENT TYPE FOR THE SAME SIZE.
THEREFORE, A DOUBLY SRM IS MORE
COMMON AND WIDELY USED.
WORKING OF SWITCH
RELUCTANCE MOTOR
AS WE KNOW THAT MAGNETIC FLUX HAVE A TENDENCY TO FLOW THROUGH LOWEST RELUCTANCE
PATH, THEREFORE ROTOR ALWAYS TENDS TO ALIGN ALONG THE MINIMUM RELUCTANCE PATH. THIS IS
THE BASIC WORKING PRINCIPLE OF SWITCHED RELUCTANCE MOTOR OR VARIABLE RELUCTANCE
MOTOR.
THEREFORE, WHEN STATOR PHASE WINDING A IS ENERGIZED, THE ROTOR ALIGN ALONG THIS PHASE
AS SHOWN IN FIGURE BELOW.
When stator phase winding A is de-energized
and winding B is energized, the rotor align itself
along B phase as shown in figure below.
Similarly, the rotor occupies a position along phase
winding C when this phase is energized.
Thus rotor rotation in clockwise direction is
achieved by energizing the phase winding in a
ABC sequence. If rotor rotation in anti-clockwise
direction is require, stator phase winding must be
energized in ACB sequence.
It must also be noted that, a particular phase
winding must be energized / de-energized in
synchronism with rotor position. This means as
soon as the rotor align along the A phase, B phase
must be energized and A phase must be deenergized if clockwise rotor rotation is required.
To better understand the working principle,
carefully observe the animation of Switched
Reluctance Motor.
Performance analysis
Advantages
Simple rotor
• This motor uses very simple rotor
making it low cost
Less manufacturing steps
Manufacturing is easy with less steps compared with other motors
Absence of brushes
Absence of brushes means that the cost is
low and no losses occurring at brushes.
High efficiency
This motor has high
efficiency also it has no
brushes meaning low
losses and higher
efficiency
Disadvantages
Pulsed torque
The nature of torque is
pulsed or non uniform
which leads to torque
ripple and noise
Position Measurment
A need to measure position
because switching of
phases in sequence is used
to run the motor
CONCLUSION