Definition of Electric Motor
Electric
Motors is an electromagnetic device that converts energy
electricity
into mechanical energy. This mechanical energy is used in industri example : rotate
the pump impeller, fan or blower , drive the compressor , lifting materials. Electric
motors are also used in household electrical appliances such as : mixer ,
electric drill , fan.
Electric
Motors Consept
Electromagnet Force ( Fleming 's left hand law )
The size of the electromagnetic force is greatest when the magnetic
field direction upright to the electric current , and increases in proportion to the length of the conductor ,
a large electric current , and the strength of the magnetic field .
As shown in the figure ,
when the coil is inserted in a magnetic field , an electric current flowing in
the opposite direction on the left and right sides , and the magnetic force
generated on the basis of Fleming 's left hand , so that coil creates a
circular motion , because this rotation continues constantly, it is needs
commutator and brush.
Work basic electric motor
Part towards the north
pole to the wire conductor and the pole south receive a force from the vertical
direction opposite to the conductor wire spinning. This is called the principle
of rotation of the motor.
The picture above can be
described as follows:
o Figure a. When the
coil or coils in the armature electrified armature will be a magnet, so that
the left side of the armature into magnetic north pole and the armature to the
right into a magnet pole South. As a result, the stator magnets and armature
magnets will be mutually contradictory so that armature will rotate.
o Figure b. Armature
still moving and until the vertical upright position a straight to the
non-magnetic field so that the armature will continue to move.
o Figure c. Armature
moves up to the position of the pole pairs (Armature north pole to the north
pole and the south pole stator armature with the south pole stator). Then
commutator reverse the current to the armature so that the magnetic field on
the armature turns. As a result, the north
pole armature met north pole stator and south pole armature met south pole stator so
contradictory and causing the armature rotates again.
Construction of Electric
Motor
Types of Electric Motor
The electric motor
consists of a rotor ( moving parts) and the stator (static part). rotor has
core magnet, and the stator has coils serves as an electric magnet when
electrified. The electric motor is classified into two types: AC electric motor (alternating
current) and DC electric motor (direct current).
1. DC Electric Motor
DC electric motor is one of
actuator the most widely used in
industrial or robotic systems. The working principle of DC motors is uses
magnets to produce rotation. The electric current flowing through the brush so
that it will cause the motor spinning. DC motor with stator electromagnet is
divided into 3 types : series electric motor, shunt electric motors and
compound electric motors.
• Series electric motor
has artmature connected with the
electromagnet in series. The electric motor of this type has characteristics a
high torque of the early rotation.
• shunt electric motor
has an armature connected to the electromagnet in
parallel. The setting
on the electric motor is much easier compared to the electric motor series.
• Compound Electric
motors has armature associated with the electromagnet in series and parallel.
2. Electric AC Motor
Electric AC motors is a
kind of electric motor which are widely used in today's modern world . Although
AC motors are mostly used for rotating equipment requiring constant speed but
use with speed control is often done in a variety of industrial applications .
The advantages of the AC
motor is as follows :
a. high efficiency
b . High reliability
c . Easy maintenance
Maintenance is easy
because AC motor not use brushes periodically be replaced .
d . Prices were
relatively cheap .
The prices were cheap
compared with a DC electric motor
because electrik ac motor not use a brush and a rectifier like is used
on a DC electric motor .
Besides the advantages above AC electric motor has a weakness
in the controlling, AC electric motors made to produce a constant speed so that to produce a varied
rotation, system requires control that quite complicated .
3. Steper Electric Motor
The stepper motor is
one types of DC motors. The difference with ordinary DC motor is a stepper
motor has a step rotations depending on the number of stator. Step use degree
rotation, ranging from 00 to 900. Part steper motors, the rotor is permanent
magnets in the stator while using electromagnet. The rotor will move when each
becomes stator magnet with electrified. Motion rotation rotor rotating step by
step in accordance with the magnetism of the stator. If all the stator has
become magnet rotor can complete one rotation.
Steper motors are widely
used in various applications of equipment that has
precision high rotation
so that no require sensors to determine position.. Motor steper divided into
three types: steper permanent magnet motors, variable reluctance motors and steper
hybrid type motor. Each has a difference in use.
In the picture above,
the rotor in the form of a permanent magnet will move from stator 2b toward the
stator 1a. The rotation resulted in the movement and angles some degree. If the
rotor is given voltage in turn to the stator 1a, 1b, 2a, 2b, and back to 1a
then all stator will become a magnet in alternately, so that the rotor will
move one full rotation from 1a, 1b, 2a, 2b and back to 1a.
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