DC motor (Direct Current motor) is an electrical machine which converts electrical energy (DC power) into mechanical energy (rotational motion). It operates based on the principle of electromagnetic induction. A current carrying conductor in a magnetic field experiences a force, which causes it to rotate.
Key Components of a DC Motor
- stator: A fixed component generating a magnetic field with the use of permanent magnets or electromagnets is called stator.
- rotor (armature): The rotating component responsible for conducting current and producing torque.
- commutator: This is a mechanical device. It reverses the direction of current through the rotor windings. This allows the rotor to rotate continuously.
- Brushes: The brushes are used to transfer electrical current from the stationary power supply to the rotating commutator.
- Field Windings: Electromagnets that create the stator’s magnetic field.
DC motor workings principle
- Upon the application of direct current, an electric current passes through the windings of the armature.
- The Lorentz force initiates rotational motion in the rotor. This force results from the interaction between the stator’s magnetic field and current in the rotor.
- The commutator changes current polarity with the rotor motion to maintain the unidirectional torque.
Types of DC Motors
- Permanent Magnet DC Motor (PMDC)— It has a stator magnetic field generated by permanent magnets.
- Brushed DC Motor— It is a configuration commonly used for small scale applications and employs brushes, a commutator.
- Brushless DC Motor (BLDC)—Uses electronic commutation technology without brushes to improve efficiency.
- Series Wound DC Motor—The series connection of field and armature windings produces high initial starting torque.
- Shunt Wound DC Motor—The field and armature windings are connected in parallel, and therefore the operation is constant speed.
- Compound Wound DC Motor— Integration of Series and Shunt Windings
DC Motor Advantages & Disadvantages
Advantages
✔ Simple control (speed adjusted via voltage).
✔ High starting torque (good for robotics, EVs).
✔ Reliable and cost-effective for small applications.
Disadvantages
✖ Brushes wear out (maintenance needed).
✖ Less efficient than AC motors at high power.
✖ Sparks and noise due to commutation.
Applications
- Electric-powered vehicles, such as forklifts and electric bicycles.
- Robotics and Drone Systems: Advanced Precision in Speed Regulation
- Fans, Toys, Power Tools, etc. domestic device
- Industrial machines (conveyors, cranes).
Speed Control Methods
- Voltage Control (adjusting supply voltage).
- PWM (Pulse Width Modulation) – Efficient speed regulation.
- Field Weakening (reducing magnetic field for higher speeds).