The Multiple Uses of DC Motors
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| DC Motors |
DC Motors are arguably the most useful type of electrical motors,
and with good reason, they are designed to be used with batteries, solar cells
or similar cell based energy sources, and as a result are used in systems where
you don't have to be tied to a wall. Furthermore, even in systems where they
are tied to the wall, sometimes it can be more efficient and cost effective to
run DC
Motors even in certain situations.
Motors generally though give the impression of a gas guzzling car. In this
article, I hope to dispel that myth, and educate you on where and when DC Motors can be
and are used.
Low Power DC Motors
The lower power motors aren't really useful for things
commonly associated with motors. Lifting and transportation applications
require more power & torque for them to work. However, what they lack in
power they make up in precision. Low power DC motors are particularly useful as
speed changes from 0 to 1 are almost instantaneous. Therefore, they can be used
successfully in digital systems.
A low speed, low power brushless DC motor can be found in
most turntable devices, particularly precision turntable devices. Devices with
such motors are things like personal computers (usually, with 3 motors in it,
one for the hard drive, and one for the processor cooler), CD & DVD
players.
Medium Power DC Motors
Medium power DC Motors have a
use too in systems. Generally they are connected to the mains, and use a
rectifier to convert the AC current into a DC current to be used for the task
in hand. As a result of this, they also need to be stepped down (voltage
reduced) so that the current doesn't overpower the circuit and burn out the
motor. This limits their usage to larger systems that require room for both a
stepper and a rectifier. But they still serve a purpose, particularly in
systems where size nor speed is an issue, just reliability. One such place is
in pinsetters in a bowling alley, for example.
High Power DC Motors
Arguably the most common and useful motors are High Power
DC Motors. These motors are generally used in open systems, and generally used
in systems were torque and power, as well as drive are paramount. Examples of
such systems include electric wheelchairs, electric scooters, Segways, hybrid
cars, as well as in elevators.
Of course, with power comes great power usage, and whilst
the most energy efficient form of motor, they can require a lot of energy to
run. Part of the creative process of using them is to be efficient (drive
systems in hybrid cars use the petrol motor's momentum to recharge a battery,
which will be then used to power the DC motor), but generally the battery will
need to be recharged or replaced at regular intervals. Even so, it's usually
infrequently the battery needs replacing. Furthermore, any systems attached to
the mains don't suffer from this problem. (By Andrew
Roberts)
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