DC Motor Basics

• DC motors are in countless consumer electronic devices from CD players to computers to radio-controlled airplanes. There are many different kinds of DC motors, but they all work on the same principle. They turn current into pulses of magnetism, which they use to turn a rotor. There are many different kinds of electric m
  
  

Brushed DC Motors

• Brushed DC Motors have two coils of wire around a rotor in the middle. Surrounding the coil are two magnets, both facing in the same direction. When the coils are facing the magnets, electricity flows into them. When electricity flows into a coil, it creates a magnetic field, and this magnetic field pushes the coils away from their magnets. As the rotor turns, the current shuts off. When the rotor has turned 180 degrees, each rotor faces the opposite magnet. The coils turn on again, this time with the electricity flowing in the opposite direction. This creates another pulse, pushing the rotor around again. The rotor has electric contacts on it, and there are small metal brushes that bump against the contacts. The brushes send in electricity, turning the motor on and off at the right times.
  
  

Brushless DC Motors

• Brushed motors work reasonably well, but they have a few drawbacks. The brushes create friction, slowing the motor and wasting energy. They also wear out. The brushes corrode or get worn away by friction from the rotor. Brushless motors solve both of these problems. A brushless motor has a permanent magnet on the inside of the rotor, facing so that its north and south poles are perpendicular to the axis of rotation. Around the rotor are coils. The coils work much like they do in a brushed motor. They give out timed pulses to push the magnet, spinning the rotor. Because there are no brushes, however, the motor can't control itself. Instead, it is attached to an electronic speed controller, which gives pulses of electricity at a certain speed to control the motor. The faster the coils pulse, the faster the motor will spin.