DC Motor Model and Advantages and Disadvantages of AC and DC Machine

1. UNIVERSITY OF ENGINEERING & TECHNOLOGY<
ABBOTTABAD CAMPUS
Electrical Machine
Title:
DC Motor Model and
Advantages and Disadvantages of AC
and DC Machine
Zunaib Ali

2. Design Motor
Task Division
Section 1
(Motor Model)
Section 2 (Advantages and
Disadvantages of DC and AC
Machine)
1. Muhammad Hafiz Saifullah
b. Satia
1. Ian Jasper
2. Muhd Izwan Ikhmal
2. Farah Aqilah bt Md Nasir
3. Shahrul Haziq Bin M.
4. Muhd Nur Farhan Bin
Hamdan
Jamil 3. Siti Norfika bt Khamis
4. Muhammad Salleh
Hassanuddin b. Sanusi
5. Shafiqrullah Bin Samsuddin.
6. Ali Syariati b. Abd Wahab

3. Design Motor
Our DC Motor Background
•Design is based on the construction of brush DC Motor.
• There are permanent magnets on the outside and a spinning
armature on the inside
•When electricity is put into this electromagnet, it creates a magnetic
field in the armature that attracts and repels the magnets in the
stator.
•The armature will spin.

4. Design Motor
Material Used and Cost
TYPE OF MATERIAL
COST
1
Wood Block
Free
2
Recycle Bottle
Free
3
Wire Winding
RM 5.00
4
Card Board
RM 7.50
5
Permanent Magnet
RM 6.00
(ceramic)
6
Car battery (sponsored)
Free
7
Soldering Flux
Free
TOTAL COST
RM18.50

5. Design Motor
TYPE OF MOTOR
BRUSH MOTOR
NUMBER OF POLE
1
AMOUNT OF VOLTAGE
12V
AMOUNT OF WINDING
20
TYPE OF MAGNET
Ceramic
USED

6. Design Motor

7. Introduction
DC Motor
 DC motor is an electric motor that runs on direct
current (DC) electricity.
 Two types of DC motor - brush and brushless DC
Motor.
 Brushed DC electric motor generates torque
directly from DC power supplied to the motor by
using internal commutation, stationary magnets
(permanent or electromagnets), and rotating
electrical magnets.
 Brushless DC motors use a rotating permanent
magnet or soft magnetic core in the rotor, and
stationary electrical magnets on the motor
housing.

8. Introduction
AC Motor
 AC motor is an electric motor driven by
an alternating current.
 Commonly consists of two basic parts, an outside
stationary stator having coils supplied with
alternating current to produce a rotating magnetic
field, and an inside rotor attached to the output
shaft that is given a torque by the rotating field.
 Two main types of AC motors- depending on the
type of rotor used.
- the asynchronous motor
- the synchronous motor

9. Operation of DC Motor

10. Operation of DC Motor
1. When the coil is powered, a magnetic field is generated
around the armature. The left side of the armature is
pushed away from the left magnet and drawn toward the
right, causing rotation.
2. The armature continues to rotate.
3. When the armature becomes horizontally aligned, the
commutator reverses the direction of current through the
coil, reversing the magnetic field.
4. The process then repeats.

11. Advantages of DC Motor
Overall advantages that will be discussed are;
1. Provide excellent speed control for acceleration and
deceleration.
2. Easy to understand design
3. Simple, cheap drive design

12. Advantages of DC Motor
 Provide excellent speed control
- power supply of a DC motor connects directly to the field
of the motor allows for precise voltage control, which is
necessary with speed and torque control applications. (DC
shunt motor)
- The higher the armature voltage, the faster the rotation.
This relationship is linear to the motor's maximum speed.
(DC series motor)

13. Advantages of DC Motor
 Easy to understand design
- The design of the brushed DC motor is quite simple. A
permanent magnetic field is created in the stator by either of
two means:


Permanent magnets
Electro-magnetic windings
- If the field is created by permanent magnets, the motor is
said to be a "permanent magnet DC motor" (PMDC).
- If created by electromagnetic windings, the motor is often
said to be a "shunt wound DC motor" (SWDC).

14. Advantages of DC Motor
 Simple and cheap drive design
-Varying the speed of a brushed DC motor requires little more
than a large enough potentiometer.
-In practice, these have been replaced for all but sub-fractional
horsepower applications by the SCR (Silicon Controlled
Rectifiers) and PWM (Pulse Width Modulation) drives, which
offer relatively precisely control voltage and current.
- Adding an SCR allows simple voltage variability simply by
turning the knob and thereby the speed of the motor.
-Pulse-width modulation is an effective method for adjusting the
amount of power delivered to an electrical load

15. Disadvantages of DC Motor
 High maintenance
- care required to maintain the mechanical interface
used to get current to the rotating field.
- maintenance includes the commutator (the
collection of copper and mica segments attached to
the rotor winding over which the brushes pass), and
the brushes themselves.
 Not suitable in very clean environment.
- vulnerable to dust which decreases
performance.

16. Operation of AC Motor
 AC motor has two basic electrical parts: a "stator"
and a "rotor“.
Rotor
Stator

17. Operation of AC Motor
 Principle of operation for all AC motors relies on
the interaction of a revolving magnetic field
created in the stator by AC current, with an
opposing magnetic field either induced on the
rotor or provided by a separate DC current so
urce.
 Resulting interaction produces usable
torque, which can be coupled to desired loads
throughout the facility in a convenient manner.

18. Advantages of AC Motor




Low cost
Speed variation
High power factor
Reliable operation

19. Advantages of AC Motor
 Low Cost
- Lowest cost motor for applications requiring more than
about 1/2 hp (325 watts).
- due to the simple design of the motor.
- For this reason, AC motors are preferred for fixed speed
applications in industrial applications and for commercial
and domestic applications where AC line power can be
easily attached.
- Over 90% of all motors are AC induction motors.
- Can be found in air
conditioners, washers, dryers, industrial
machinery, fans, blowers, vacuum cleaners and many
other.

20. Advantages of AC Motor
 Speed variation
- The fixed number of winding sets (known as poles) built
into the ac motor, which determines the ac motor's base
speed.
- The frequency of the AC line voltage. Variable speed drives
(Adjustable speed drives) change this frequency to change the
speed of the motor.
- The amount of torque loading on the motor, which causes
slip.

21. Advantages of AC Motor
 High power factor
- power factor of an AC electrical power system is defined
as the ratio of the real power flowing to the load to
the apparent power in the circuit.
- a load with a low power factor draws more current than a
load with a high power factor for the same amount of
useful power transferred.
- higher currents increase the energy lost in the distribution
system, and require larger wires and other equipment.

22. Advantages of AC Motor
Reliable Operation
-The simple design of the AC motor results in extremely
reliable, low maintenance operation.
-Unlike the DC motor, there are no brushes to replace.
-If run in the appropriate environment for its enclosure,
the AC motor can expect to need new bearings after
several years of operation. If the application is well
designed, an AC motor may not need new bearings for
more than a decade.

23. Disadvantages of AC Motor
 Inability to operate at low speeds
- We know that standard AC motors should not be operated at
speeds less than about 1/3 of base speed. This is due to thermal
considerations. In fact a DC motor should be considered for these
applications.
 Poor positioning control
- Positioning control is expensive and crude with AC motors too.
Even a vector drive is very crude when controlling the standard AC
motor.
- Servo DC motors are more appropriate for these applications.

24. Disadvantages of AC Motor
 AC will produce eddy currents due to the production
of a back emf.
- Because motors are generators that operate in reverse, they
produce an emf just like generators do.
- Called as back emf and does not immediately appear when
a motor is initially turned on.
- The back emf is a consequence of Lenz's law, which states
that an induced emf produces a magnetic flux that resists the
change.
- Back emf works to reduce the current in the loop, thus
slowing the motor down, and it gets larger as the speed of the
motor increases.

25. Conclusion
 The advantages and disadvantages of DC and AC
motor somehow depends on application used.
• The reference of DC and AC refers how the
electrical current is transferred through and from
the motor. Both the types of the motors have
different functions and applications.
• However, AC motor is widely used in industry
application that support AC source voltage.