A presentation on Electric Motor and its working principle, components, it's classification, types of AC & DC motor, special types of motors & its application.

1. Presentation By
Rahmat Ullah
B. Tech. (E.I.E)

2.  Electric Motor - Definition
 Working Principle of Electric Motor
 Basic Components of Electric Motor
 Classification of Electric Motor
 AC Motor – Definition
 Working Principle of AC Motor
 Types of AC Motor & it’s definition
 1- Ø Vs 3 – Ø Induction Motor
 DC Motor – Definition
 Working Principle of DC Motor
 Types of DC Motor & it’s definition
 Permanent Magnet DC Motor
 Brushless & Brushed DC Motor
 Special Types of Motor
 Application of Electric Motor

3.  An electric motor is an electrical machine that
converts electrical energy into mechanical
energy.
 History was made when Thomas Davenport of
Vermont invented the first official battery-
powered electric motor in 1834.
 Electric motors can be powered by alternating
(AC) current or direct current (DC).

4.  Joseph Henry & Michael Faraday created early
motion devices using electromagnetic fields.
 This was the first electric motor that had
enough power to perform a task and
his invention was used to power a small-scale
printing press.

5.  A motor shaft spins as a result of interaction
between two magnetic fields: One produced
by the electromagnet at the stator and the
other by the electromagnet at the rotor.

8.  Rotor/ Armature: The rotor in an electric motor is
the moving part, and the main function of this is
to rotate the shaft for generating the mechanical
power.
 Generally, the rotor includes conductors which
are laid to carry currents, and communicate with
the magnetic field in the stator.
 The rotating part of the motor - this used to be
called a rotor, it supports the rotating copper
coils.
 Stator: The stator in the motor is the inactive part
of the electromagnetic circuit. It includes
permanent magnets or windings. The stator can
be built with different thin metal sheets which
are known as laminations. These are mainly used
for reducing energy losses.

9.  Windings/Coil: Windings in the motors are
wires that are laid inside of the coils,
generally covered around a flexible iron
magnetic core so as to make magnetic poles
while energized with the current.
 For motor windings, copper is the most
frequently used material. Copper is the most
common material for windings and aluminum
is also used although that should be solid to
carry a similar electrical load securely.

10.  Bearings: The bearings in the motor mainly
give the support to the rotor to activate its
axis.
 The shaft of the motor expands with the help
of the bearings to the load of the motor. As
the load forces are used outside of the
bearing, then the load is known as overhung.

12.  An AC motor is an electric motor driven by
an alternating current (AC).
 The motor that converts the alternating
current into mechanical power by using an
electromagnetic induction phenomenon is
called an AC Motor.
 The stator and the rotor are the two most
important parts of the AC motors. The stator is
the stationary part of the motor. And the rotor
is the rotating part of the motor.
 An AC motor may be single phase or three
phase.

13.  The fundamental operation of an AC
Motor depends on the principle of
magnetism. The simple AC Motor contains a
coil of wire and two fixed magnets
surrounding a shaft.
 When an electric (AC) charge applies to the
coil of wire, it becomes an electromagnet.
This electromagnet generates a magnetic
field.

14.  In the case of an AC motor, a rotating
magnetic field is produced at the stator when
3 phase power is applied while the rotor field
is stationary.

15.  Hence, the North pole of the rotor field
constantly gets attracted towards the South
pole of the stator field and vice versa.
Likewise, similar poles of the rotor and the
stator repels.

16. 1) Synchronous Motor
i. Hysteresis Motor
ii. Reluctance Motor
2) Asynchronous / Induction Motor
 On the basis of Rotor
i. Squirrel Cage Induction Motor
ii. Phase Wound Induction Motor
 On the basis of Phase
i. Single Phase Induction Motor
ii. Three Phase Induction Motor

17.  The machine that changes the alternating
current into mechanical power at the desired
frequency is known as the synchronous motor.
 In the synchronous motor, the speed of the
motor is synchronised with the supply current
frequency.
 The synchronous speed is measured regarding
the rotation of the magnetic field, and it
depends on the frequency and the poles of the
motor.

18.  The synchronous motor is classified into two
types
i. Reluctance Motor
ii. Hysteresis motor.
 Reluctance Motor – The motor whose starting
process is similar to an induction motor and
which runs like a synchronous motor is
known as the reluctance motor.
 SRM motors can be used in analog electric
meters.
 Used in some washing machine designs.
 These can be used in electric vehicles.

20.  System cost is low
 This motor is having high efficiency.
 It is having heat tolerance because of the
absence of copper winding.
 Robust construction
 It is having a high power density
 These motors are having a constant long
power range.
 These are having high speed.
 SRM motor follows the quadrant operation

21.  Hysteresis Motor – The hysteresis motor is
the type of a synchronous motor which has
the uniform air gap and does not have any DC
excitation system.
 The torque in the motor is produced by the
hysteresis and the eddy current of the motor.

22.  It can be operated either using a single phase
or three phases and in a noiseless operating
environment.
 It maintains a constant speed.
 The torque generated in the motor is due to
the hysteresis and eddy current which is
induced due to stator winding.
 There are 4 types of hysteresis motor:
 Cylindrical type
 Disk type
 Circumferential-Field type
 Axial-Field type

23.  An induction motor or asynchronous motor is
an AC electric motor in which the electric
current in the rotor needed to produce torque
is obtained by electromagnetic induction from
the magnetic field of the stator winding.
 The machine which never runs at synchronous
speed is called the induction or asynchronous
motor. This motor uses electromagnetic
induction phenomenon for transforming the
electric power into mechanical power.

24.  Squirrel Cage Rotor – The motor which
consists squirrel cage type rotor is known as
a squirrel cage induction motor. The squirrel
cage rotor decreases the humming sound and
the magnetic locking of the rotor.

25.  Phase Wound Rotor /Slip Ring Rotor IM– This
rotor is also known as the slip ring rotor, and
the motor using this type of rotor is known as
the phase wound rotor.

26.  Single Phase Induction Motor: Single phase
induction motors are the simple motors
which operate on single phase A.C. and in
which torque is produced due to induction of
electricity caused by the alternating magnetic
fields.
 A single phase induction motor consists of a
single phase winding on the stator and a cage
winding on the rotor.

28.  When a 1 phase supply is connected to the
stator winding, a pulsating magnetic field is
produced.
 In the pulsating field, the rotor does not rotate
due to inertia.
 Therefore a single phase induction motor is
not self-starting and requires some particular
starting means.

29.  Some single-phase AC electric motors require
a "run capacitor" to energize the second-
phase winding (auxiliary coil) to create a
rotating magnetic field while the motor is
running. Start capacitors briefly
increase motor starting torque and allow
a motor to be cycled on and off rapidly.
 Two theories have been suggested to find the
performance of a single phase induction
motor.
◦ Double revolving field theory.
◦ Cross-field theory.

30.  Three Phase Induction Motor: The motor
which converts 3-phase AC electric power
into mechanical power, such type of motor is
known as a three-phase induction motor.
 3 phase induction motor, as this type of
motor does not require an additional starting
device. These types of motors are known as
self-starting induction motors.

31.  The stator of the motor consists of
overlapping winding offset by an electrical
angle of 120o.
 When we connect the primary winding, or the
stator to a 3 phase AC source, it establishes
rotating magnetic field which rotates at the
synchronous speed.
 The rotating magnetic field rotates at the
synchronous speed Ns=120f/P.

34.  A DC motor is an electrical machine that
converts electrical energy into mechanical
energy. In a DC motor, the input electrical
energy is the direct current which is
transformed into the mechanical rotation.

35.  When kept in a magnetic field, a current-carrying
conductor gains torque and develops a tendency
to move. In short, when electric fields and
magnetic fields interact, a mechanical force
arises. This is the principle on which the DC
motors work.

36.  In DC motor, the stator field remains
stationary and the rotor field is changed by
changing the direction of current from in it
using a commutator.
 Hence, the North pole of the rotor field
constantly gets attracted towards the South
pole of the stator field and vice versa.
Likewise, similar poles of the rotor and the
stator repels.

38.  Separately Excited Motor: The motor in which the
DC winding is excited by the separate DC source
is known as the separately excited dc motor.
 With the help of the separate source, the
armature winding of the motor is energised and
produce flux.

39.  Self-Excited Motor: In self-excited DC
motors, the field winding is connected either
in series or parallel to the armature winding.
 Based on self-excited DC motor, can further
be classified as:
◦ Shunt Wound DC Motor
◦ Series Wound DC Motor
◦ Compound Wound DC Motor

40.  Shunt Wound DC Motor: In a shunt wound
motor, the field winding is connected parallel
to the armature as shown in the figure.

41.  Owing to the fairly constant speed and
medium starting torque of shunt DC motors,
they are used in the following applications:
◦ Centrifugal and Reciprocating Pumps
◦ Lathe Machines
◦ Blowers and Fans
◦ Drilling Machines
◦ Milling Machines
◦ Machine Tools

42.  Series Wound DC motor: In a series wound DC
motor, the field winding is connected in
series with the armature winding as shown in
the figure.

43.  Owing to the high starting torque and
variable speed of series DC motors, they are
used in the following applications:
◦ Conveyors
◦ Hoists, Elevators
◦ Cranes
◦ Electric Locomotives

44.  Compound Wound DC Motor: DC motors
having both shunt and series field winding is
known as Compound DC motor, as shown in
the figure.

45.  Owing to the high starting torque of
cumulative compound DC motors, they are
used in the following applications:
◦ Shears
◦ Heavy Planers
◦ Rolling mills
◦ Elevators

46.  The term PMDC stands for “Permanent
Magnet DC motor”. It is one kind of DC motor
which can be inbuilt with a permanent
magnet to make the magnetic field necessary
for the electric motor operation.
 PMDC Motor’s rotor includes armature core,
commutator, & armature winding.
 The operating voltage of the PMDC motor is 6
volts, 12 volts otherwise 24 volts DC supply
attained from the voltage sources.

47.  The PMDC motor’s permanent magnets are
maintained with a cylindrical-steel stator and
these supplies like a return lane for the magnetic
flux.
 The rotor supplies like an armature, and it
includes commutator segments, winding slots, &
brushes like in conventional dc machines.

48.  PMDC are classified into three namely
◦ Alnico Magnets,
◦ Ceramic (Ferrite) Magnets
◦ Rare-earth Magnets.
 Alnico magnets are used within motors which
have the ratings in the range of 1kW-150kW.
 Ferrite or Ceramic magnets are much cheap
within fractional kw (kilowatt) motors.
 Rare-earth magnets are made with samarium
cobalt as well as neodymium iron cobalt.

49.  A brushless DC motor, also known as
synchronous DC motor, unlike brushed DC
motors, do not have a commutator. The
commutator in a brushless DC motor is
replaced by an electronic servomechanism
that can detect and adjust the angle of the
rotor.
 A brushed DC motor features a commutator
that reverses the current every half cycle and
creates single direction torque. While brushed
DC motors remain popular, many have been
phased out for more efficient brushless
models in recent years.

51.  Direct Drive: Direct drive is a high-efficiency,
low-wear technology implementation that
replaces conventional servo motors and their
accompanying transmissions. In addition to
being far easier to maintain over a longer
period of time, these motors accelerate more
quickly.
 Linear Motors: These electric motors feature
an unrolled stator and motor, producing
linear force along the device’s length. In
contrast to cylindrical models, they have a flat
active section featuring two ends. They are
typically faster and more accurate than
rotatory motors.

52.  Servo Motors: A servo motor is any motor
coupled with a feedback sensor to facilitate
positioning; thus, servo motors are the
backbone of robotics. Both rotary and linear
actuators are used. Low-cost brushed DC
motors are common, but are being
superseded by brushless AC motors for high-
performance applications.

53.  Stepper Motors: Stepper motors use an
internal rotor, electronically manipulated by
external magnets. The rotor can be made
with permanent magnets or a soft metal. As
windings are energized, the rotor teeth align
with the magnetic field. This allows them to
move from point to point in fixed increments.

54.  Universal Motor: This is a special kind of
motor and this motor works on single AC
supply otherwise DC supply.
 Universal motors are series wound where the
field and armature windings are connected in
series and thus generates high starting
torque.
 These motors are mainly designed for
operating at high-speed above 3500 rpm.
They utilize AC supply at low-speed and DC
supply of similar voltage.

55.  The applications of electrical motor mainly
include blowers, fans, machine tools, pumps,
turbines, power tools, alternators,
compressors, rolling mills, ships, movers,
paper mills.
 The electric motor is an essential device in
different applications like HVAC- heating
ventilating & cooling equipment, home
appliances, and motor vehicles.

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