A Brushed DC (Direct Current) motor is a type of electric motor that converts electrical energy into mechanical rotational motion. It is called "brushed" because it uses physical brushes and a commutator to switch the direction of current flow in the motor's coil windings. While Brushed DC motors were widely used in the past, they have been largely replaced by Brushless DC motors (BLDC) and other more advanced technologies due to their drawbacks in terms of maintenance and efficiency.
Here's how a typical Brushed DC motor operates:
Construction: The motor consists of several key components, including a rotor (armature), a stator with permanent magnets, a commutator, brushes, and coil windings. The rotor is the rotating part of the motor, while the stator remains stationary. The commutator is a segmented ring connected to the rotor, and the brushes maintain physical contact with the commutator.
Power Supply: When a voltage is applied across the coil windings, a current flows through them. The brushes and commutator play a critical role in changing the direction of the current in the coil windings, which creates a rotating magnetic field.
Electromagnetic Principle: The magnetic field generated by the coil windings interacts with the permanent magnets in the stator, causing the rotor to rotate. As the commutator rotates with the rotor, the brushes make contact with different segments of the commutator, reversing the current flow in the coil windings, and thus reversing the direction of the magnetic field.
Continuous Rotation: This process of switching the direction of the current flow allows the rotor to keep rotating continuously in the same direction, as long as the power supply is maintained and the brushes and commutator remain functional.
Motion Control Systems:
Brushed DC motors were extensively used in various motion control systems in the past, thanks to their relatively simple control mechanisms. Some of the applications include:
Industrial Machinery: They were used in conveyor belts, automated assembly lines, and other industrial equipment where simple speed and direction control were required.
Automotive: They were employed in electric windows, windshield wipers, and electric seat adjustments.
Robotics: In early robotic systems, brushed DC motors were utilized in the joints and actuators.
Consumer Electronics: They were found in appliances like hairdryers, electric shavers, and small household gadgets.
However, despite their past widespread use, Brushed DC motors have several limitations. The friction between the brushes and commutator causes wear and tear, leading to maintenance issues and reducing the motor's lifespan. Additionally, the physical contact between brushes and commutator results in electrical noise and reduced efficiency. As a result, Brushed DC motors have been largely replaced by more efficient and reliable technologies like Brushless DC motors and AC induction motors in most modern motion control systems.