UPSC » UPSC CSE Study Materials » Physics » Motors

Motors

A motor is a device that converts electrical energy into mechanical energy. The essential concept behind the operation of an electric motor is Faraday's Law of Induction.

The term “motor” refers to any power unit that generates motion, often known as a “prime mover,” whereas “electric motor” refers to a “prime mover that employs electricity.”

Electric motors are machines that convert electric power into motive energy or electrical energy into mechanical energy. Mechanical output (motive energy) can be shortened to output, whereas electrical input can be abbreviated to read input. During the energy conversion process, some input is transformed to heat rather than motive energy.

This is known as “loss.”

Electric Motor

An electric motor is a device that converts electrical energy into mechanical energy. Most electric motors operate by reacting between the motor’s magnetic field and the electric current in a wire winding. This contact generates a force in the form of torque, which is applied to the shaft of the motor.

Electric motors are used in a range of applications such as autos, trains, power tools, fans, air conditioning, household appliances, and many more.

The Principle behind the operation of an electric motor is Faraday’s Law of Induction.

Components of a Motor

Before understanding what is the principle of an electric motor, we need to know the components of a motor.

Motor components are divided into five categories.

  •   Rotor Spinning portion
  •   Bearing Supporting part of the rotor’s rotating shaft
  •   Stator
  •   Bracket or end plate creating force utilized to revolve the rotor: The stator’s bearing supporting component

·   Lead wire: A wire attached to the drive circuit, which provides power to the motor, or a wire connected to the power supply

Principle of Electric Motor- Faraday’s Law of Electromagnetic Induction

Faraday’s Law of Electromagnetic Induction is the Principle of Electric Motors.

Faraday’s Law of Electromagnetic Induction (also known as Faraday’s law) is a basic law of electromagnetism that describes how a magnetic field interacts with an electric circuit to produce an electromotive force (EMF). This is known as electromagnetic induction.

Faraday’s law of induction describes the operation of transformers, motors, generators, and inductors.

A current will be created in a conductor subjected to a changing magnetic field, according to Faraday’s law. The induced current’s direction will be such that the magnetic field established by the induced current opposes the initial changing magnetic field that produced it, according to Lenz’s law of electromagnetic induction.

The right-hand rule of Fleming can be used to determine the direction of this current flow.

Types of motors

Electric motors have now become more and more versatile and adaptive. The most common electric motors in use today are:

  •   AC Brushless Motors

AC brushless motors are among the most widely used motors. The induction of a spinning magnetic field which is created in the stator to turn both the stator and the rotor at the same time is employed in them. They are powered by permanent electromagnets.

  •       Brushed DC Motors

The brush orientation on the stator determines the current flow in a DC motor. In other versions, the orientation of the brush relative to the rotor bar segments is more important. The commutator is crucial in every design of a DC motor.

  •       Brushless DC Motors

DC brushless motors were created to deliver superior performance in a smaller space than DC brushed motors, and they are even smaller than equivalent AC counterparts. In the absence of a slip ring or commutator, an integrated controller is utilised to assist operation.

  •   Direct Drive

Direct drive is a high-efficiency, low-wear technology that substitutes traditional servo motors and their associated gearboxes. These motors have faster acceleration and are significantly easier to maintain over a longer period of time.

  •   Linear Motors

These electric motors have an unrolled stator and motor which helps in providing a linear force over the length of the device. As opposed to cylindrical variants, they consist of a flat active portion with two ends. They are often more precise and quicker  than rotatory motors.

Conclusion

Motors are often powered by electricity, and too much current can be damaging. Motor running and stall currents are crucial. The operational current is the average amount of current drawn by the motor under typical torque circumstances. Heat sinks are required to keep the coils from melting if the motor is continually running or if the voltage is higher than the rated voltage.

Voltage is used to keep net current flowing in just one direction and to overcome back current. The torque increases as the voltage increases.

The general rule is that motors function best at high speeds, however this is not always possible if gearing is required. Adding gears affects motor efficiency, thus consider both speed and torque decreases.

These are the essentials to consider while selecting a motor. Pay attention to the application’s parameters, such as voltage, current, torque, and velocity, since these will determine which motor is best suited.

faq

Frequently asked questions

Get answers to the most common queries related to the UPSC Examination Preparation.

What is the relation between Speed, Power and Torque?

Ans. Power(P)= Speed(n) X Torque(M)

How can the speed of electric motors be increased?

Ans. The strength of the magnetic field must be changed to make the motor spin faster or slower. This is achieved by...Read full

Is it possible to utilise an electric motor as a generator?

Ans: Despite the fact that an electric motor and a generator both utilize the same current, a motor cannot be ‘swi...Read full

How can electric motors increase their revolutions per minute (RPM)?

Ans: The tempo may be increased by increasing the frequency. If a motor’s base speed is 60 Hz, raising the fre...Read full