A single phase induction motor works using a single phase power supply with two windings on the stator: a main winding and an auxiliary winding. It cannot self-start due to the alternating magnetic field produced. Various methods are used to generate a rotating magnetic field and enable self-starting, including split phase, shaded pole, and capacitor start designs. Single phase induction motors find applications in appliances, tools, and equipment where only single phase power is available.

1. SINGLE PHASE INDUCTION MOTOR

2.  A single-phase motor is an electrically-powered rotary
machine that can turn electric energy into mechanical
energy.
 It works by using a single-phase power supply. They contain
two types of wiring: hot and neutral.
 Their power can reach 3Kw and supply voltages vary in
unison.

4.  Electric motors let us obtain mechanical energy in the
simplest and most efficient manner.
 Depending on the number of supply phases, we can
find single-phase, two-phase and three-phase motors
with coiled startup winding and with coiled startup winding
with a capacitor.
 And choosing one or the other will depend on the
necessary power.
 If you are involved in a project and don’t know what type of
motor you should use, this will interest you! In it, we tell you
about each motor and their differences

5.  A single-phase motor is an electrically-powered rotary
machine that can turn electric energy into mechanical
energy.
 It works by using a single-phase power supply. They
contain two types of wiring: hot and neutral. Their power can
reach 3Kw and supply voltages vary in unison.
 They only have a single alternating voltage. The circuit
works with two wires and the current that runs across them is
always the same.

6.  In most cases these are small motors with a limited torque.
However, there are single-phase motors with a power of up to
10 hp that can work with connections of up to 440V.
 They do not generate a rotating magnetic field; they can only
generate an alternate field, which means that they need a
capacitor for startup.
 They are easy to repair and maintain, as well as affordable.
 This type of motor is used mainly in homes, offices, stores
and small non-industrial companies. Their most
common uses include home appliances, home and business
HVAC and other appliances such as drills, air conditioners and
garage door opening and closing systems.

8.  A two-phase motor is a system that has two voltages 90
degrees apart, which is no longer in use nowadays. The
alternator is composed of two windings placed at 90 degrees
from each other.
 They require 2 live and one ground wire that work in two
phases. One increases the current up to 240v for the motion,
and the other one maintains the fluidity of the current for the
use of the motor.

9.  A three-phase motor is an electric machine that transforms
electric power into mechanical energy by means
of electromagnetic interactions.
 Some electric motors are reversible – they can transform
mechanical energy into electric power acting as generators.
 They work by using a three-phase power source. They are
driven by three alternating currents of the same frequency,
which peak at alternating moments.
 They can have a power of up to 300KW and speeds ranging
between 900 and 3600 RPM.
 Three conductor lines are used for transmission, but the final
use requires 4-wire cables, which correspond to the 3 phases
plus neutral.

10. Three-phase electric power is the most common
method in use in electric grids around the world
since it transfers more power, and it sees significant
use in the industrial sector.

11.  First, we need to differentiate the type of installation and the
current that flows through it. In this regard, the difference
between single-phase current and three-phase current lies
in that single-phase current is transferred over a single line. In
addition, since there is only one phase or alternating
current, the voltage does not vary.
 Single-phase motors are used when a three-phase system is
not available and/or for limited power – they are generally
used for powers under 2 Kw or 3 Kw.

13.  Three-phase motors commonly see more use in industry,
since their power is over 150% greater than that of a single-
phase motor, and a three-phase rotating magnetic field is
generated.
 While running a single-phase motor can be noisy and
generate vibrations, three-phase motors are more expensive,
but they do not generate these vibrations and are less noisy.

14.  Single-Phase Induction Motor
 Construction
 Operation
 Types of 1-Phase Induction
Motors

15.  The single-phase motors are more preferred over a three-phase
induction motor for domestic, commercial applications.
Because form utility, only single-phase supply is available.
 So, in this type of application, the three-phase induction
motor cannot be used.
 in the following post, we will be showing the construction and
different types of 1-phase induction motors with working and
applications.

16.  A single phase induction motor is similar to the three phase
squirrel cage induction motor except there is single phase two
windings (instead of one three phase winding in 3-phase
motors) mounted on the stator and the cage winding rotor is
placed inside the stator which freely rotates with the help of
mounted bearings on the motor shaft.
 The construction of a single-phase induction motor is similar
to the construction of a three-phase induction motor.

18.  Similar to a three-phase induction motor, single-phase
induction motor also has two main parts;
 Stator
 Rotor

19.  In stator, the only difference is in the stator winding. The stator
winding is single-phase winding instead of three-phase
winding.
 The stator core is the same as the core of the three-phase
induction motor.
 In a single-phase induction motor, there are two winding are
used in stator except in shaded-pole induction motor.
 Out of these two windings, one winding is the main winding
and the second is auxiliary winding.
 The stator core is laminated to reduce the eddy current loss.
The single-phase supply is given to the stator winding (main
winding)

20.  Rotor of single-phase induction motor is the same as a rotor of
squirrel cage induction motor. Instead of rotor winding, rotor
bars are used and it is short-circuited at the end by end-rings.
Hence, it makes a complete path in the rotor circuit. The rotor
bars are braced to the end-rings to increase the mechanical
strength of the motor.
 The rotor slots are skewed at some angle to avoid magnetic
coupling. And it also used to make a motor run smooth and
quiet.
 The following fig shows the stator and rotor of a 1-phase
induction motor.


22.  Single-phase AC supply is given to the stator winding (main winding).
 The alternating current flowing through the stator winding produces
magnetic flux. This flux is known as the main flux.
 Now we assume that the rotor is rotating and it is placed in a magnetic
field produced by the stator winding.
 According to Faraday’s law, the current start flowing in the rotor
circuit it is a close path. This current is known as rotor current.
 Due to the rotor current, the flux produced around the rotor winding.
This flux is known as rotor flux.
 There are two fluxes; main flux which is produced by stator and
second is the rotor flux which is produced by the rotor.
 Interaction between main flux and rotor flux, the torque produced in
the rotor and it starts rotating.

23.  The stator field is alternating in nature. The speed of the stator
field is the same as synchronous speed. The synchronous
speed of the motor depends on the number of pole and supply
frequency.
 It can represent by two revolving fields. These fields are equal
in magnitude and rotating in the opposite direction.
 Let say Φm is a maximum field induced in the main winding.
So, this field is divided into two equal parts and that is Φm/2
and Φm/2.
 Out of these two fields, one field Φf is rotating in an
anticlockwise direction and the second field Φb is rotating in a
clockwise direction. Therefore, the resultant field is zero.
 Φr = Φf – Φb

24.  Φr = Φf – Φb
 Φr = 0
 Now consider the resultant field at different instants.

25. When a motor starts, two fields are induced as shown
in the above figure. These two fields are the same
magnitude and opposite direction. So, resultant flux is
zero.

26.  In this condition, the stator field cannot cut by rotor field and
resultant torque is zero. So, the rotor cannot rotate but it
produces humming.


27.  Now consider after the rotation of 90˚, both filed are rotated
and pointing in the same direction. Therefore, the resultant
flux is a summation of both fields.
 Φr = Φf + Φb
 Φr = 0
 Φr = 0

28.  In this condition, the resultant filed is equal to the maximum
field induced by the stator. Now, both fields rotate separately
and it is alternative in nature.
 So, both fields cut by the rotor circuit and EMF induced in the
rotor conductor. Due to this EMF, the current starts flowing in
the rotor circuit and it induces a rotor flux.
 Due to the interaction between stator flux and rotor flux motor
continues to rotate. This theory is known as Double
Revolving Theory or double field revolving theory.


29.  Now, from the above explanation, we can conclude that
the single-phase induction motor is not self-starting.
 To make this motor self-starting motor, we need stator flux
rotating in nature instead of alternating nature. This can be
done by various methods

30.  Types of Single-phase Induction Motors
 The single-phase induction motors are classified as;
 Split Phase Induction Motor
 Shaded Pole Induction Motor
 Capacitor Start Induction Motor
 Capacitor Start Capacitor Run Induction Motor
 Permanent Capacitor Induction Motor

31.  In this type of motor, an extra winding is wounded on the same core
of the stator.
 So, there are two windings in the stator.
 One winding is known as the main winding or running winding and
second winding is known as starting winding or auxiliary winding.
 A centrifugal switch is connected in series with the auxiliary
winding.
 The auxiliary winding is highly resistive winding and the main
winding is highly inductive winding.
 The auxiliary winding has few turns with a small diameter.
 The aim of auxiliary winding is to create a phase difference between
both fluxes produced by the main winding and rotor winding.

33.  The connection diagram is as shown in the above figure. The
current flowing through the main winding is IM and current
flowing through the auxiliary winding is IA.
 Both windings are parallel and supplied by voltage V.
 The auxiliary winding is highly resistive in nature. So, the
current IA is almost in phase with supply voltage V.
 The main winding is highly inductive in nature. So, the current
IM lags behind the supply voltage with a large angle.

34.  The total stator flux is induced by the resultant current of these
two winding. As shown in the phasor diagram, the resultant
current is represented as (I).
 It will create a phase difference between fluxes and resultant
flux produces a rotating magnetic field. And the motor starts
rotating.
 Auxiliary winding only uses to start the motor. This winding
is not useful in running condition.
 When the motor reaches 75 to 80 % of synchronous speed,
the centrifugal switch opens.
 So, the auxiliary winding is out from the circuit. And motor
runs on only main winding.

35.  The phase difference creates by this method is very small.
Hence, the starting torque of this motor is poor.
 So, this motor is used in low starting torque applications like a
fan, blower, grinder, pumps, etc.

36.  As compared to other types of single-phase induction motor,
this motor has a different construction and working principle.
This type of motor does not require auxiliary winding.
 This motor has stator salient pole or projecting pole and the
rotor is the same as squirrel cage induction motor.
 The stator poles are constructed specially to create a rotating
magnetic field.
 A pole of this motor is divided into two parts; shaded part and
un-shaded part.
 It can be created by cutting pole into unequal distances.

37.  A copper ring is placed in the small part of the pole. This ring
is a highly inductive ring and it is known as a shaded ring or
shaded band. The part at which shaded ring is paced is known
as shaded part of the pole and the remaining part is an
unshaded part.
 The construction of this motor is as shown in the below figure.

39.  When an alternating supply passing through the stator
winding, an alternating flux induced in the stator coil.
 Due to this flux, some amount of flux will link with shaded
ring and current will flow through a shaded ring.
 According to Len’z law, the current passing through coil is
opposite in nature, and flux produced due to this coil will
oppose the main flux.
 The shaded ring is a highly inductive coil.
 So, it will oppose the main flux when both fluxes are in the
same direction and it will increase the main flux when both
fluxes are in the opposite direction.

40.  So, it will create a phase difference between the main flux
(stator flux) and rotor flux. By this method, a phase difference
is very less. Hence, the starting torque is very less. It is used in
applications like toy motor, fan, blower, record player, etc.


41.  In this type of motor, two capacitors are connected in parallel
with series in auxiliary winding. Out of these two capacitors,
one capacitor is used only for starting (starting capacitor) and
another capacitor is connected permanently with the motor
(running capacitor).
 The circuit diagram of this figure is as shown in the below
figure.

43.  The starting capacitor has high capacitance value and a
running capacitor has low capacitance value. The starting
capacitor is connected in series with a centrifugal switch
that will open when the speed of the motor is 70% of
synchronous speed.
 During running conditions, both running winding and
auxiliary winding connected with motor. The starting
torque and efficiency of this motor are very high.
 Therefore, this can be used in the application where high
starting torque is required like a refrigerator, air
conditioner, ceiling fan, compressor, etc.


44.  The low-value capacitor is connected constantly with the
auxiliary winding. Here, the capacitor has low capacitance.
 The capacitor is used to increase the starting torque but it is
low compared to the capacitor start induction motor.


45.  The circuit diagram and phasor diagram of
this motor is as shown in the below figure.

47.  The power factor and efficiency of this motor are very high
and also it has a high starting torque that is 80% of full load
torque.
 This type of motor is used in the application like an exhaust
fan, blower, heater, etc.

48.  Single phase motors are not self starting and less efficient than three
phase induction motor and available in 0.5HP to 15HP and still they are
widely used for multiple purposes such as:
 Clocks
 Refrigerators, freezers and heaters
 Fans, table fans, ceiling fan, exhaust fans, air coolers and water coolers.
 Blowers
 Washing machines
 machine tools
 Dryers
 Type writers, photostats and printers
 Water pumps and submersible
 Computers
 Grinders
 Drilling machines
 Other Home instrument, equipment and devices etc.

49.  The equivalent circuit of a Single Phase Induction
Motor can be obtained by two methods named the Double
Revolving Field Theory and Cross Field Theory.
 Firstly the equivalent circuit is developed on the basis of
double revolving field theory when only its main winding is
energized.

50.  Considering the case when the rotor is stationary and only the
main winding is excited.
 The motor behaves as a single-phase transformer with its
secondary short circuit. The equivalent circuit diagram of the
single phase motor with only its main winding energized is
shown below:


52.  Here,
 R1m is the resistance of the main stator winding.
 X1m is the leakage reactance of the main stator winding.
 XM is the magnetizing reactance.
 R’2 is the standstill rotor resistance referred to as the main
stator winding.
 X’2 is the standstill rotor leakage reactance referred to as the
main stator winding.
 Vm is the applied voltage.
 Im is the main winding current.

53.  The core loss will be assumed to be lumped with the
mechanical and stray losses as a part of the rotational losses of
the rotor.
 The pulsating air gap flux in the motor at the standstill is
resolved into two equal and opposite fluxes with the motor.
 The standstill impedance of each of the rotors referred to as
the main stator winding is given as:

54.  The equivalent circuit of a single-phase single winding
induction motor with the standstill rotor is shown below.
 The forward and the backward flux induces a voltage Emf and
Emb respectively in the main stator winding.
 Em is the resultant induced voltage in the main winding.

55.  At the standstill condition Emf = Emb
 Now, with the help of an auxiliary winding, the motor is
started.
 As the motor attains its normal speed, the auxiliary winding is
removed.
 The effective rotor resistance of an induction motor depends
on the slip of the rotor.

57.  In the above circuit diagram, the air gap portion is split into
two parts.
 The first part shows the effect of forward rotating flux and the
second part shows the effect of the backward rotating flux.
 The effective rotor resistance with respect to the forward
rotating flux is R’2/2S and with respect to the backward
rotating flux is R’2/2 (2-s).
 When both forward and backward slips are taken into account,
the equivalent circuit shown below is formed.
 In this condition, the motor is running on the main winding
alone.

59.  The rotor impedance representing the effect of the forward
field referred to the stator winding m is given by an impedance
shown below:
The rotor impedance of a single phase induction motor
representing the effect of the backward field referred to the
stator winding m is given by an impedance shown below:

61.  The simplified equivalent circuit of a single-phase induction
motor with only its main winding energized is shown in the
figure below:

62. The above equation (3) is the equation of the current in the stator
winding.

63.  A special machine is a semi or 100% automatic machine
which allows specific operations dedicated to a product or a
family of products to be carried out.
 These machines can carry out one or more operations, for
example, assemblies, vision checks and packaging.


64.  The products that surround you on a daily basis are very likely to have one
day been shaped by a special machine (Vehicle, perfumery, household
appliances, Hifi ...).
 These machines are generally designed and manufactured in a single copy,
this continually represents a technological and industrial challenge for
manufacturers.
 The design and manufacture of a machine requires the intervention of a
multitude of trades:
 Industrial design
 Manufacture of mechanical parts, boilermaking
 Mechanical assembly of the assemblies
 Wiring of the machine and electrical cabinets
 Automation and robotics programming
 Developments and validations in real conditions
 User training
 The machines also require the integration of commercial components or
materials, carefully selected by the technicians.


65.  What are the types of special
machines?
 Various types of special purpose electric machines
including universal motor, permanent magnet motor,
reluctance motor, brushless DC motor, stepper motors,
linear induction motor and hysteresis motor are presented.
The construction, operation, characteristics and applications of
each machine are described.

66.  Special Electrical Machines and Drives
 Stepping Motors
 Constructional features, principle of operation, modes of excitation,
single phase stepping motors, torque production in variable
Reluctance (VR) stepping motor, Dynamic characteristics, Drive
systems and circuit for open loop control, Closed loop control of
stepping motor, microprocessor based controller
 Switched Reluctance Motors
 Constructional features, principle of operation. Torque equation,
Power controllers, Characteristics and control. Microprocessor
based controller. Sensor less control.

67.  Synchronous Reluctance Motors
 Constructional features: axial and radial air gap Motors. Operating principle,
reluctance torque – Phasor diagram, motor characteristics.
 Permanent Magnet Brushless DC Motors
 Commutation in DC motors, Difference between mechanical and electronic
commutators, Hall sensors, Optical sensors, Multiphase Brushless motor, Square
wave permanent magnet brushless motor drives, Torque and emf equation, Torque-
speed characteristics, Controllers-Microprocessor based controller. Sensor less
control.
 Permanent Magnet Synchronous Motors
 Principle of operation, EMF, power input and torque expressions, Phasor diagram,
Power controllers, Torque speed characteristics, Self control, Vector control,
Current control schemes. Sensor less control.


68.  (D) The term “special purpose motor” means any motor,
other than a general purpose motor or definite purpose
motor, which has special operating characteristics or
special mechanical construction, or both, designed for a
particular application.

69.  AC series motors are also known as the modified DC series motor as their
construction is very similar to that of the DC series motor. Before we
discuss these modifications, here it is essential to discuss what is the need
and where do we need to do modifications.
 In order to understand this, consider this question. What will happen when
we give an AC supply to DC series motor? Answer to this question is
written below:
 An AC supply will produce an unidirectional torque because the direction
of both the currents (i.e. armature current and field current) reverses at the
same time.
 Due to presence of alternating current, eddy currents are induced in the
yoke and field cores which results in excessive heating of the yoke and
field cores.
 Due to the high inductance of the field and the armature circuit, the power
factor would become very low.
 There is sparking at the brushes of the DC series motor.


70.  So considering above points we can say that we don’t have good
performance of DC series motor on the application of AC supply.
 Now in order to reduce the eddy currents there is need to laminate
the yoke and field core. This is our first modification to DC series
motor.
What about power factor how we can improve power factor? Now
the power factor is directly related to reactance of the field and
armature circuit and we can reduce the field winding reactance by
reducing the number of turns in the field winding.


71.  But there is one problem: on reducing the number of turns, field mmf will
decrease and due to this the air gap flux decrease.
 The overall result of this is that there is an increase in the speed of the
motor but decrease in the motor torque which is not desired.
 Now how to overcome this problem? The solution to this problem is the
use of compensating winding.
 On the basis of the usage of compensating winding we have two types of
motor and they are written below:
 Conductively compensated type of motors.
 Inductively compensated type of motors

72.  Given below is the circuit diagram of the conductively
compensated type of motors.
 In this type of motor, the compensating winding is connected
in series with the armature circuit. The winding is put in the
stator slots. The axis of the compensating winding is 90o
(electrical) with main field axis.


73.  Given below is the circuit diagram of the inductively
compensated type of motors.
 In this type of motor, the compensating winding has no
interconnection with the armature circuit of the motor.
 In this case, a transformer action will take place as the
armature winding will act as primary winding of the
transformer and the compensation winding will acts as a
secondary winding.
 The current in the compensating winding will be in phase
opposition to the current in the armature winding.


75.  Given below is the complete schematic diagram of the single
phase AC series motor with all the modifications (i.e.
compensating winding and inter pole).

76.  Speed control of this type of motor is best obtained by solid state device.
The motor has numerous applications such as portable drills, hair dryers,
table fans, kitchen appliances, etc. We have already discussed the
advantage of having compensating winding.
 Let us discuss what is the use of the inter pole? The main function of the
inter poles is to improve the performance of the motor in terms of higher
efficiency and a greater output from the given size of the armature core.
 We have taken very high reactive voltage drop of series field as compared
to either armature or the compensating field in order to reduce the series
filed inductance.
 The winding of the inter pole circuit is connected in parallel with the non
inductive shunt as shown in the above figure.

77.  A universal motor is a special type of motor that runs on
both AC and DC power supplies.
 Universal motors are series-wound (the armature and field
windings are in series).
 The series connection allows them to generate high torque;
hence the universal motors are generally built into the device
they are meant to drive.

78.  Examples include portable hand tools, blenders, vacuum
cleaners and sewing machines.
 The universal motor may be recognized by its distinctive
whirring sound when running.

79.  Two types of universal motors are in use, namely, non-
compensated and compensated.
 The non-compensated motor is usually built with concentrated
or salient poles .
 On the other hand, the compensated motor has distributed
field windings (main field and compensating winding).


81.  A universal motor is a special type of motor which is designed to run on
either DC or single phase AC supply.
 These motors are generally series wound (armature and field winding are
in series), and hence produce high starting torque (See characteristics of
DC motors here).
 That is why, universal motors generally comes built into the device they
are meant to drive. Most of the universal motors are designed to operate at
higher speeds, exceeding 3500 RPM.
 They run at lower speed on AC supply than they run on DC supply of same
voltage, due to the reactance voltage drop which is present in AC and not
in DC.
There are two basic types of universal motor : (i)compensated type and
(ii) uncompensated type.

82.  Construction of a universal motor is very similar to
the construction of a DC machine.
 It consists of a stator on which field poles are mounted. Field
coils are wound on the field poles.
 However, the whole magnetic path (stator field circuit and also
armature) is laminated.
 Lamination is necessary to minimize the eddy currents which
induce while operating on AC.

84.  The rotary armature is of wound type having straight or
skewed slots and commutator with brushes resting on it.
 The commutation on AC is poorer than that for DC. because
of the current induced in the armature coils.
 For that reason brushes used are having high resistance.

86.  A universal motor works on either DC or single phase AC
supply. When the universal motor is fed with a DC supply, it
works as a DC series motor. (see working of a DC series
motor here).
 When current flows in the field winding, it produces an
electromagnetic field. The same current also flows from the
armature conductors.
 When a current carrying conductor is placed in an
electromagnetic field, it experiences a mechanical force. Due
to this mechanical force, or torque, the rotor starts to rotate.
The direction of this force is given by Fleming's left hand rule.

87.  When fed with AC supply, it still produces unidirectional
torque. Because, armature winding and field winding are
connected in series, they are in same phase.
 Hence, as polarity of AC changes periodically, the direction of
current in armature and field winding reverses at the same
time.

Thus, direction of magnetic field and the direction of armature
current reverses in such a way that the direction of force
experienced by armature conductors remains same.
 Thus, regardless of AC or DC supply, universal motor works
on the same principle that DC series motor works.

88.  Speed/load characteristics of a universal motor is similar to
that of DC series motor.
 The speed of a universal motor is low at full load and very
high at no load.
 Usually, gears trains are used to get the required speed on
required load.
 The speed/load characteristics are (for both AC as well as DC
supply) are shown in the figure.

90.  Universal motors find their use in various home appliances
like vacuum cleaners, drink and food mixers, domestic sewing
machine etc.
 The higher rating universal motors are used in portable drills,
blenders etc.

91.  A stepper motor is an electromechanical system which is
transducing an electrical signal into a mechanical one.
 It is designed to accomplish a discrete movement (notion of
step) and reach a precise position.
 The movement is achieved through the use of a magnetic field
provided by coils and sensed by magnets.


92.  Commercially, stepper motors are used in floppy disk drives,
flatbed scanners, computer printers, plotters, slot
machines, image scanners, compact disc drives, intelligent
lighting, camera lenses, CNC machines, and 3D printers.


93.  A stepper motor is an electromechanical device it converts electrical power
into mechanical power.
 Also, it is a brushless, synchronous electric motor that can divide a full
rotation into an expansive number of steps.
 The motor’s position can be controlled accurately without any feedback
mechanism, as long as the motor is carefully sized to the application.
Stepper motors are similar to switched reluctance motors.
 The stepper motor uses the theory of operation for magnets to make the
motor shaft turn a precise distance when a pulse of electricity is provided.
 The stator has eight poles, and the rotor has six poles. The rotor will
require 24 pulses of electricity to move the 24 steps to make one complete
revolution.
 Another way to say this is that the rotor will move precisely 15° for each
pulse of electricity that the motor receives.

94.  The construction of a stepper motor is fairly related to a DC
motor.
 It includes a permanent magnet like Rotor which is in the
middle & it will turn once force acts on it. This rotor is
enclosed through a no. of the stator which is wound through a
magnetic coil all over it.
 The stator is arranged near to rotor so that magnetic fields
within the stators can control the movement of the rotor.

95.  The stepper motor can be controlled by energizing every stator
one by one.
 So the stator will magnetize & works like an electromagnetic
pole which uses repulsive energy on the rotor to move
forward.
 The stator’s alternative magnetizing as well as demagnetizing
will shift the rotor gradually &allows it to turn through great
control.

96.  The stepper motor working principle is Electro-Magnetism.
It includes a rotor which is made with a permanent magnet
whereas a stator is with electromagnets.
 Once the supply is provided to the winding of the stator then
the magnetic field will be developed within the stator.
 Now rotor in the motor will start to move with the rotating
magnetic field of the stator.
 So this is the fundamental working principle of this motor.

97. In this motor, there is a soft iron that is enclosed
through the electromagnetic stators.
The poles of the stator as well as the rotor don’t
depend on the kind of stepper.
Once the stators of this motor are energized then
the rotor will rotate to line up itself with the stator
otherwise turns to have the least gap through the
stator.
In this way, the stators are activated in a series to
revolve the stepper motor.