Skip to main content

Brushed D.C. Motors vs Brushless D.C. Motors

BRUSHED D.C. MOTORS vs BRUSHLESS D.C. MOTORS

What is a brush?
A brush is a silver, copper, or graphite compound that transfers electric current from the power source to the commutator(electromagnet polarity changing element of an electric DC motor).
How do brushed DC motors work?
Brushed DC motors function as a result of the interaction between a rotating electromagnet and a mechanical rotary switch that maintains the current’s direction. The electromagnet, part of a system called an armature(the thing that spins the motor), is created by electric current passing through a rotating set of 2 or more wire coils. The mechanical rotary switch, called a commutator, changes the polarity of the armature every cycle so that the armature can push or pull on the permanent magnets that are on the outside part of the motor to continue spinning.
How do brushless DC motors work?
Brushless DC motors work as a result of the interaction between an external rotor that is a permanent magnet and three pairs of driving coils (electromagnets). The brushless motor also has a set of drive electronics that control which pair of driving coils is activated at a given time. A brushless motor works by activating the three sets of driving coils in series so that they push the external permanent magnet around the center shaft. The stages of driving coil activation can be adjusted to various speeds by the electronic speed controller.
Brushed vs Brushless
Brushed - A brushed motor is controlled by two wires: it is simple to control due to the lack of electronics as well as the analog nature of the control(voltage based). This lack of electronics allows brushed motors to function in extreme environments. Brushed motors are difficult in the necessity for frequent maintenance to replace brushes as well as less reliability and longevity. Generally, brushed motors are more simple to manufacture, build, and control but lack the refinement of brushless motors.
Brushless - Brushless motors are controlled by electronic speed controllers and a system of sensors which allows for more precise control than the mechanical switch for brushed motors. The lack of brushes (which wear down over time and need to be replaced) allows for less frequent maintenance. Brushless motors have more consistent speed and torque as well as a generally greater efficiency. They have a greater ratio of power to size than their bulkier brushed relatives as a result of their better thermal characteristics. The speed is limited only by voltage and therefore has a wider range than brush/commutator reliant motors. While being more expensive and complex to produce and construct(especially the expensive electronic elements), brushless motors are a more refined and longer lasting solution that are more likely to fit a variety of use cases.
Anatomy of brushed DC motor vs brushless DC motor
brushed-brushless.jpgGeneral comparison and explanation
Scientific publication discussing the benefits of brushless DC motors

Comments

Post a Comment

Popular posts from this blog

Physics of Sound Dampeners and Active Noise Cancellation

Physics of Sound Dampeners and Active Noise Cancellation Sound dampening foam panels in a recording studio. ANC headphones worn by pilots and/or passengers in consumer aviation aircraft.  Acoustic treatment of soundscapes has grown alongside the sound production industry. Whether through absorption panels, diffusors and cloud panels to treat a space or headphones placed directly over the ears of listeners, acoustic treatment comes in many forms. Environments are treated acoustically to absorb excess sound to prevent sound levels from crossing a threshold above which the desired goal cannot be had. Before getting into sound dampening, we must discuss sound. Sound is produced when an object vibrates (a form of oscillation) and temporarily displaces nearby air molecules causing a wave effect as the displaced molecules collide with their neighboring molecules. Sound waves are fluctuations in pressure as the initial displacement of molecules experiences collisions that in ...
Post a Comment
Read more

Large Hadron Collider

The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator. The LHC is the largest machine in the world. It took thousands of scientists, engineers and technicians decades to plan and build, and it continues to operate at the very boundaries of scientific knowledge. It first started up on 10 September 2008, and remains the latest addition to CERN’s accelerator complex. The LHC consists of a 27-kilometre ring of superconducting magnets with a number of accelerating structures to boost the energy of the particles along the way. Map of LHC (located in Geneva, Switzerland) Thousands of magnets of different varieties and sizes are used to direct the beams around the accelerator.  Just prior to collision, another type of magnet is used to "squeeze" the particles closer together to increase the chances of collisions. The particles are so tiny that the task of making them collide is akin to firing two needles 10 kilometres apart with suc...
Post a Comment
Read more

Aerodynamics of a Golf Ball

One may wonder how a small golf ball can travel at incredibly high speeds for such long distances.  While the swing of the club is a major component, the structure of the golf ball is quite important.  Unlike a baseball or tennis ball, a golf ball has dimples all over it (usually 336 dimples).  These dimples allow the golf ball to travel without facing much air resistance.  This diagram shows how air travels around the golf ball. The dimples on the golf ball also prevent drag that would occur in the wake region, resulting in further distance.  Also due to the contact with the club during the swing, the golf ball has backspin during its entire flight.  This diagram shows the motion of the golf ball mid flight with the lift force of F. There are hundreds of different types of golf balls that a player can choose.  Some show little affect to a player's game while others can alter their performance completely.  Personally, I prefer Callaway Supers...
Post a Comment
Read more