DCmotors

DC motors are machines that convert direct current electrical energy into mechanical energy. They are widely used whenever adjustable speed or high starting torque is required.

Brushed DC motors have a stator that provides a magnetic field and a rotor with windings connected to a commutator and brushes. When voltage is applied, current in the rotor windings produces torque through interaction with the stator field. The rotor also generates a back-EMF that increases with speed, reducing net voltage and thereby limiting speed.

Brushless DC motors (BLDC) use electronic commutation rather than brushes. Permanent magnets are typically on the rotor, while the stator contains windings driven by a controller that sequences phases according to rotor position.

Common brushed configurations include series, shunt, and compound. In a series motor the field current adds to the armature current, giving high starting torque but speed varies with load; in a shunt motor the field is connected in parallel and speed is more constant.

Control methods rely on adjusting voltage or current. Pulse-width modulation with power electronics is standard for both brushed and brushless types, with BLDC controllers using rotor-position feedback.

Applications include robotics, CNC machines, electric vehicles, power tools, conveyors, and actuators.

Advantages include high starting torque and good speed control; drawbacks include brush wear in brushed motors and the need for electronics in BLDC systems.

Performance depends on design, cooling, and controls; DC motors cover a wide range of sizes from tiny hobby motors to large industrial units.