Objectives of the lesson:

After this lesson students will be able to build a simple

electric DC motor

DC Motor (Direct Current Motor)

A DC motor is an electrical machine that converts direct current (DC) electrical energy into mechanical (rotational) energy. It works on the principle that a current-carrying conductor placed in a magnetic field experiences a force, causing the rotor to rotate. (NIDEC CORPORATION)

Main Parts of a DC Motor

• Stator – Produces the magnetic field.

• Rotor (Armature) – Rotating part carrying the windings.

• Commutator – Reverses the current direction in the armature to maintain continuous rotation.

• Brushes – Transfer electrical current from the power supply to the rotating commutator.

• Shaft – Delivers the mechanical output.

Working Principle

1. DC power is supplied to the motor.

2. Current flows through the armature windings.

3. A magnetic field is produced around the armature.

4. The interaction between the armature's magnetic field and the stator's magnetic field creates torque.

5. The commutator reverses the current at the correct time, allowing the rotor to keep rotating in the same direction. (ITP NYU)

Types of DC Motors

• Permanent Magnet DC (PMDC) Motor

• Series DC Motor

• Shunt DC Motor

• Compound DC Motor

• Brushless DC (BLDC) Motor

Advantages

• High starting torque.

• Easy speed control.

• Quick start and stop.

• Suitable for variable-speed applications.

Disadvantages

• Brushes and commutator require maintenance (in brushed DC motors).

• Brush wear can produce sparks.

• Generally more maintenance than AC or brushless motors.

Applications

• Electric vehicles

• Cranes and hoists

• Robotics

• Power tools

• Fans and pumps

• Toys and household appliances

• Conveyor systems (groschopp.com)