Electric Motors seems to be
included in most household appliances today. The primary part of every
mechanical movement that we see in our environment is made possible by Electric
Motors. Either powered by AC or DC sources.
Brushed Motors
In order for us to easily
understand what we are talking about, here are the basic parts of an electrically
powered DC motor:
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| Image Source: www.embedded.com |
As you can see in the
image above, its main parts consist of permanent
magnets, armature, brushes, shaft, commutator and coils. The permanent magnets are
positioned on the outside layer, surrounding the armature inside. The magnets
are stationary or does not move from its position that is why it’s called as STATOR.
On the other hand, the armature rotates, that is why it’s called as the ROTOR.
Electromagnet is what the
armature is made up, and when electricity flows through it, it produces a
magnetic field in the armature that makes the magnets in the stator to be
attracted and repelled. The armature can only spin up to 180 degrees. So, in
order for it to spin continuously, we have to change the polarity of the
electromagnet. For that process to be possible, the brushes is positioned so
that it can make contact with the electrodes attached to the armature and flips
the polarity of the electromagnets as it continually spins. The process will
continue not unless the source of electricity runs out.
The advantage of this motor set
up is that it is very easy to manufacture and will not cost a lot of bucks. It
may not be pricy, but it has its downfalls such as : the easy wear out of the
brushes, it is harder to cool down because the electromagnet is placed at the
center, the speed of the motor is very limited because of the brushes, the
number of poles is also limited, and it generates electrical noise.
Brushless Motors
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| Image Source: www.mathworks.com |
The parts of the Brushless DC
Motor is the same as that of the Brushed one, only the positions of the parts
are inverted. In Brushed Motors, the permanent magnets are in the stator, but
in BLDC Motors, the magnets are in the ROTOR. And the electromagnets are placed
in the STATOR.
With the emergence of computer,
the motor system can be controlled efficiently unlike with the use of brushes. Electrical
noise is much lesser compared to the brushed one. And you don’t need to worry
about brushes anymore. The position of
the electromagnets is another advantage because they are very easy to cool. If you
want to gain more precision on the motor, adding more electromagnets on the
stator will do the trick.
The only disadvantage of this
type of motor is the greater cost in manufacturing, but the cost will be
recovered because the efficiency is improved and will last long compared to the
brushed motors.
