WHY IS BRUSHLESS BETTER?
Below is some text from an article from Popular Mechanics website:
How Old-School Brushed Motors Work
A traditional brushed motor is made
up of four basic parts: carbon brushes,
a ring of magnets, an armature, and a
commutator. The magnets and brushes
are stationary, while the armature and
commutator rotate together on the
motor shaft within the magnets.
When the motor is energized, a charge
travels from the battery, through the
brushes, and into the commutator. (The
brushes are spring-loaded to maintain
physical contact with the commutator.)
The commutator then passes the charge
on to the armature, which is made up
of copper windings (they look like
bundles of copper wire). The windings
are magnetized by the charge and push
against the stationary ring of magnets
that surround it, forcing the armature
assembly to spin. The spin doesn’t stop
until the charge from the battery stops.
How Brushless Motors Work
A brushless motor loses the brushes and
the commutator. And the locations of
the magnets and windings are reversed:
The magnets are on the conventional
motor shaft and the copper windings
of the armature are fixed and surround
the shaft. Instead of brushes and a
commutator, a small circuit board
coordinates the energy delivery to the
windings.
Because the electronics communicate
directly with the stationary windings,
the tool adjusts according to the task
- which is why the companies market
these as “smarter” tools. For example,
if you’re using a brushless drill to drive
screws into Styrofoam, it more readily
senses the lack of resistance (compared
with a brushed motor) and begins to pull
only what little charge it needs from the
battery. If the tool then starts putting
three-inch screws into mahogany, it
will adjust accordingly and draw more
current. By contrast, a brushed motor
will always run as fast as it can while in
use.
In addition, brushless motors can be
more powerful overall. Because the
copper windings are on the outside of
the motor configuration, there is room
to make them larger. Brushless motors
also don’t have the friction and voltage
drop that brushes create by dragging
against the spinning commutator. This
physical contact results in a continuous
energy loss during the operating
process.
The net gain is a tool with greater efficiency and more durable motors.