DC Motor

A machine that converts electrical energy into mechanical energy is known as an electric motor. When a current-carrying conductor is put in a magnetic field, it is subjected to forces that aid in shaft or axle rotation.

A motor is a mechanical device that converts electrical energy into mechanical energy. Spinning blades in a mixer, for example, mash and incorporate contents. The mixer’s electric energy is turned into mechanical energy when the blade rotates, producing the desired action.

Principle of electric motor

Many scientists contributed to the development of the electric motor. A magnetic field is created by an electric current travelling through a conductor. This was initially noticed in the 19th century by Hans Christian Oersted. The magnetic effect of electric current is the name for this phenomenon. A current-carrying conductor put in a magnetic field encounters a force that causes the conductor to move, according to Andre Marie Ampere, a French scientist. A moving field generates an electric current, as demonstrated by English physicist Michael Faraday. Their experiments, as well as those of many other scientists, contributed to the development of machinery such as motors and generators.

In a magnetic field, a current-carrying conductor is placed. It is pushed in a direction that is perpendicular to both the field and the current by a force. The direction of movement can be determined using Fleming’s left-hand rule.

Consider two bar magnets with their poles facing each other and separated by a narrow escape. A small length of conducting wire is fashioned into a loop and inserted into the gap between the magnets, where it will be surrounded by the magnetic field created by the magnets. The loop starts spinning as soon as the ends are connected to the battery contacts. This is because the magnetic field of the magnet interferes with the electric current flowing through the conductor. Due to the magnetic poles created in the circle, the induced South Pole is pulled to the North Pole, and vice versa. The South Pole becomes the North Pole as the current in the circle reverses, and it is dragged to the magnet’s south pole.

Construction of DC motor

• Battery: A battery is a DC power source that is commonly used to power a basic motor. It feeds the armature coil with DC current.

• Brushes: The electric motor has two carbon brushes that act as a connection between the commutator and the battery terminals.

• Permanent magnets: Permanent magnets provide a powerful magnetic field.

• Commutator: Commutator of the split ring type: The commutator is responsible for reversing current in the armature coil. It’s made up of two parts of a metallic ring. The two ends of the armature coil are attached to the metallic rings of these two parts.

• Armature core: The armature core holds the armature coil in place while also providing mechanical support.

• Armature coil: A single or more rectangle-shaped loops of insulated copper wire make up an armature coil.

• Axle or Shaft: This is the location where mechanical power is exchanged. On the shaft, the armature core and commutator are placed.

Working of a DC motor

It is powered by direct current DC. Let us simplify its structure to a single coil between two poles to better understand how it works.

Towards the north pole, current flows from A to B, and near the south pole, current flows from C to D. As a result, the field lines and the current direction are perpendicular to each other. As a result, the sides AB and CD are subjected to a force whose direction is determined by Fleming’s left-hand rule.

Side AB is subjected to an upward force, whereas side CD is subjected to a downward force. As a result, the rectangular coil ABCD moves in a circular motion. Due to the split ring, current flows in the directions D to C near the north pole and B to A near the south pole after the half rotation. As a result, the force on both sides does not change direction, and the coil rotates constantly.

Losses in DC motor

Copper power losses are caused by electrical winding resistance, whereas iron power losses are caused by hysteresis and eddy currents in the armature’s iron core. While the iron loss is nearly constant from no load to full load, the copper loss varies greatly depending on the load current.

These are the two most common electrical losses in motors, and they’re put together to get the total electric power loss. In copper conductors, power loss is proportional to the square of the current flowing  P=I2R.

Conclusion

We’ve seen how the interaction between electricity and the magnetic field is used to create a moving force in this article. Motors are separated into two types based on the source of electricity: DC and AC motors. Depending on the source of electricity, the sorts of electricity, and the nature of the task to be done, we employ several types of motors. Some jobs require big loads, while others necessitate the correct speed. Motors and their windings are also built differently depending on the source and the work they have to execute.