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Brushless Motors Vs Brush Motors
- Jul 17, 2017 -

                                                        What’re the differences between a Brushless Motor and a Brush Motor ?

The principle behind the internal working of both a brushless DC motor and a brushed DC motor are essentially the same.  When the motor windings become energized, a temporary magnetic field is created that repels(and/or attracts) against permanent magnets.  This force is converted into shaft rotation, which allows the motor to do work.  As the shaft rotates, electric current is routed to different sets of windings, maintaining electromotive repulsion/attraction,  forcing the rotor to continually turn.

Construction differences

Brushes inside  electric motors are used to deliver current to the motor windings through commutator contacts.  Brushless motors have none of these current carrying commutators.  The field inside a brushless  motor is switched via an amplifier triggered by a commutating device, such as an optical encoder.

Brushed motor Advantages:

Simplified  wiring:  Brush motors can be wired directly to DC power and control can be a simple as a switch.

Low cost:

Brushed Motor Disadvantages:

Less efficient

Electrically noisy: The switching action of the commutators constantly creating and breaking inductive circuits creates a great deal of electrical and electromagnetic noise.

Brushless Motor Advantages:

Long lifespan: No brushes to wear out
low maintenance: No brushes to replace
High efficiency

Brushless Motor disadvantages:

High initial cost: Need for commutating device  like an encoder and a drive or controller

Brusheless motor vs brush motor efficiency:

Brushless motors are typically 85-90% efficient whereas brushed DC motors are around 75-80% efficient.

This difference in efficiency means that more of the total power used by the motor is being turned into rotational force and less is being lost as heat.