Here are the key points about brushed DC motors:
- It consists of an armature (rotating part) and a stator (stationary field part).
- The armature has a commutator which is a cylinder split into segments insulated from each other. Brushes ride on the commutator and provide electric contact.
- Windings are placed on the armature which carry current and produce electromagnetic force. Permanent magnets on the stator provide static magnetic field.
- Current flow creates a magnetic field around the armature windings. This interacts with the static field of the permanent magnets resulting in a rotational force (torque) as per Fleming’s left hand rule.
- As the armature rotates, the commutator switches the current direction in the windings to reverse the magnetic poles. This maintains the torque in one direction.
- The commutator and brushes arrangement allows bidirectional current flow through the armature as it rotates.
- Speed control is achieved by varying the applied voltage. Higher voltage leads to higher armature current, stronger torque and increased speed.
- Has high starting torque but speed is limited to around 5000 rpm. Well suited for applications like electric drills, toys, locomotive motors etc.
Following are some common applications where brushed DC motors are used:
- Electric vehicles – Brushed DC motors were traditionally used in electric cars and trains to provide traction power. Though now being replaced by brushless motors.
- Cordless power tools – Drills, circular saws, jigsaws etc often use brushed DC motors because of their high starting torque and speed control capability.
- Toys – Small cheap DC motors are very commonly used in toy cars, model trains, drones etc. Their low cost, simplicity and ability to run on low voltages make them ideal.
- Window motors in vehicles – Brushed DC motors are used to raise and lower power windows in many cars. They can directly run on 12V car battery.
- Small fans – Portable fans, desk fans often use small brushed DC motors around 10-50W power range. They provide adequate airflow while being low cost.
- Automation – In production lines, robotic arms, pick-and-place machines, brushed DC motors are used to provide precise position and speed control.
- Household appliances – Mixers, blenders, vacuum cleaners, treadmills use brushed DC motors matched to the specific speed and torque requirements.
- Computer peripherals – HDDs, DVD drives, printers use small brushed DC motors for rotary motion and positioning.