Working Principle of DC Motor: A 2022 Complete Guide

An electrical device known as a DC motor that┬átransforms electrical energy into mechanical energy. Direct current, which is used as an electrical energy source in a DC motor, is converted into mechanical rotation. In this working principle of DC motor, 2022 complete guide, we’ll provide you a thorough explanation of what a DC motor is, as well as its several components┬áand working.

What is DC motor?

A direct current (DC) motor is a type of electric motor that converts electrical energy into mechanical energy.

The aforementioned definition leads us to the conclusion that a DC motor is any electric motor that is run on direct current, or DC. In the following sections, we’ll learn about DC motor construction and how a DC motor transforms the electrical energy it receives from a DC source into mechanical energy.

Main components of DC Motor

The following are the principal components of a DC motor:

Stator or a Field Coil

A DC motor field coil is a stationary component that has winding wound on it to create a magnetic field. Between its poles, this electromagnet contains a cylindrical hollow.

Brushes

A carbon and graphite structure is used to create the brushes for a DC motor. From the external circuit to the revolving commutator, these brushes carry electric current. As a result, it becomes clear that the commutator and brush unit are involved in transferring power from the dynamic electrical circuit to the mechanically revolving area, or rotor.

Armature or Rotor

An insulated cylinder made of magnetic laminations serves as the armature of a DC motor. The cylinder’s axis and the armature are parallel. The field coil and the armature, a revolving component that spins on its axis, are separated from one another by an air gap.

Commutator

The commutator of a DC motor is a cylindrical construction constructed of mica-insulated copper segments that are piled on top of one another. A commutator’s main job is to feed the armature winding with electrical current.

Working of DC Motor

The key components of a DC motor were covered in the section before this one. Let’s now use this information to better grasp how DC motors works.

When the field coil of the DC motor is energized, a magnetic field develops in the air gap. The generated magnetic field is directed in the radial direction of the armature. The magnetic field “enters” the armature from the field coil’s South pole side and “exits” it from the North pole side.

The basis for how a DC motor operates is the idea that anytime a current-carrying conductor is positioned inside a magnetic field, it feels a magnetic force whose direction is determined by Fleming’s Left-hand Rule. In other words, the DC motor rotates as a result of the magnetic fields of the current-carrying electromagnet and the permanent magnet interacting.

A force of the same magnitude but acting in the opposite direction is applied to the conductors situated on the other pole. The torque produced by these two opposing forces makes the motor armature revolve.

Application of Fleming Left-Hand Rule

A current-carrying wire and magnetic flux are necessary for the DC motor’s working principle. Think about a coil that runs a DC current through brushes and a commutator. The segments of this commutator may freely revolve about their axis. Positive polarity is applied to the commutator segment that makes contact with the left brush, while negative polarity is applied to the right one. This causes electricity to flow through the coil.

The conductor on the left side always receives an upward force, according to Fleming’s Left-Hand Rule, whereas the conductor on the right side always experiences a downward force. So, with DC motors, a unidirectional torque is produced.

Backing EMF

An EMF is formed in the conductor as a result of the interaction between the current-carrying conductor and the varying magnetic field created by the field coil. This EMF, also known as back EMF, behaves in the opposite direction to the applied voltage. The amount of back EMF is inversely proportional to the motor’s speed. EMF armature current will start to decrease when the back is increased. Since the torque is inversely proportional to the armature current, it will also fall until the load can be supported. As a result, the motor’s speed will be controlled.

A DC motor’s speed will drop and its back EMF will rise if it is quickly loaded. The torque will rise to meet the load demand as armature current rises.

Working principle of DC motor

When held in a magnetic field, a conductor carrying current produces torque and begins to move. In essence, when electric and magnetic fields interact, a mechanical force is created. This idea underlies the operation of DC motors.

Types of DC Motor

Electric shavers to vehicles are just a few of the many uses for DC motors. Based on the connections of the field winding to the armature, they are divided into many varieties to accommodate this large variety of applications.

  • Separately Excited DC Motor
  • Self-Excited DC┬áMotor

Let’s now go into more depth about the various DC motor kinds.

Self-Excited DC Motor

The field winding and armature winding are coupled in self-excited DC motors either in series or parallel. As a result, the self-excited DC motor can also be categorized as:

  • Shunt wound DC motor
  • Series-wound DC motor
  • Compound winding DC motor

Separately Excited DC Motor

A separately excited DC motor that has a DC external source powers the field coils.

DC motor Applications

The following is a list of the applications for several DC motors:

Cumulative Compound DC motors

Cumulative compound DC motors have a powerful beginning torque, which makes them ideal for the following applications:

  • Large Planers
  • Shears
  • Elevators
  • Rolling machines

DC Shunt Motors

They are employed in the following applications because shunt DC motors have a relatively consistent speed and a moderate starting torque:

  • Reciprocating and centrifugal pumps
  • Fans and Blowers
  • Milling machines┬á
  • Lathe machines
  • Drilling equipment
  • Machine tools

Series DC Motors

The following applications employ series DC motors because of their strong starting torque and variable speed:

  • Conveyors
  • Lifts and Hoists
  • Cranes
  • Electrified Trains

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