Types of Electric Motor and Uses – AC and DC Motor Explained Details

In this 21st century without electricity, we can't imagine doing any of our jobs. There is a major development that happened in technology and civilization only after the introduction of electricity and electrical devices.

We can’t imagine our life without ceiling fans, lights, computers, communication devices and many more.  It is proved that electricity and electrical devices play a major role in our life to make it easy and advance.

One such equipment which is continuously using in our domestic and industrial sector is the Motor. There are different varieties of motors used in different sectors according to their requirements. In this article, we are going to learn about the types of electric motors.

The electrical motor is the biggest advancements in the engineering and technology field ever since the invention of electricity.

What is an Electric Motor?

An electric motor is an electro-mechanical machine that converts electrical energy into mechanical energy. Basically, the motor produces the rotational force.

The working principle of the all-electric motor depends on the interaction between the magnetic and electric field.

Mainly, an electric motor has two types and they are AC motor and the DC motor. Let’s see these types of an electric motor in detail.

# AC Motor

The AC motor requires an alternating current to rotate. This motor converts the alternating current into mechanical power using electromagnetic induction.  The AC motor has two most important parts and they are stator and rotor.

Where the stator is the stationary part and the rotor is the rotating part of the motor. Mostly, AC motors are single-phase or three-phase.

The three-phase AC motor produces bulk power and mostly used in the industry. The single-phase AC motors used in small power applications. The single-phase AC motor is small in size and used in a variety of services.

Most of the domestic appliances such as refrigerators, fans, washing machines and mixers use the single-phase AC motor.

# DC Motor

A motor that converts the DC power into mechanical power is referred to as a DC motor. It is operated by the DC current. The basic working principle of a DC motor is that when a current-carrying conductor is placed in a magnetic field, a force exerted on it develops the torque.

The DC motor consists of two main part: Armature & Stator. The rotating part is the armature and their stationary part is the Stator.

Types of AC Motor

AC motors are mainly classified into three types and they are,

• Synchronous Motor
• Asynchronous or Induction Motor
• Linear Motor

1. Synchronous Motor

The synchronous motor changes the alternating current into mechanical power at the desired frequency. In this motor, the speed of the motor is synchronised with the AC frequency. Theses motors mainly depend on the three-phase supply.  In this, the motor speed is the constant speed at which the motor generates an electromotive force.

There is no air gap available in the speed of the stator current and rotor. So it provides more rotation accuracy. Because of high rotation accuracy, these motors are applicable in automation, robotics, etc.

The synchronous motor is segmented into two types:

(i) Reluctance Motor

The motor whose construction is similar to an induction motor and runs like a single-phase synchronous motor is called the reluctance motor.

In this motor, the rotor is like squirrel cage type and the stator include sets of windings such as auxiliary and main winding. To offer a level operation at a stable speed, the auxiliary windings are very useful.

These motors are commonly used in signal generators, recorders etc. which requires the proper synchronization.

(ii) Hysteresis Motor

The hysteresis motor has a uniform air gap and doesn’t have any DC excitation system. The rotor of this motor induces the hysteresis and eddy current to complete its required task. The working of a motor depends on the construction, single-phase or three-phase supply.

These motors provide very smooth operation with stable speed similar to other synchronous motors. The noise level of this motor is quite small, due to this reason they are used in the applications where the soundproof motors are required like a sound player, audio recorder etc.

2. Induction Motor

An induction motor or an asynchronous motor runs with asynchronous speed. It uses electromagnetic induction for transforming electric energy into mechanical power.

According to rotor construction, there are two types of induction motor. They are squirrel cage induction motor and phase wound induction motor.

On the basis of supply phases, the induction motor is classified into single-phase and three-phase induction motor.

(i) Squirrel Cage Rotor

The rotor of the motor has the shape of a squirrel cage.  In this, the inner component connected to the output shaft and looks like a cage. This rotor decreases the magnetic locking and the humming sound of the rotor.

(ii) Phase Wound Rotor

This rotor is a variation of the three-phase induction motor which is designed to provide high torque for loads with high inertia while taking very low current. It is also known as slip ring motors.

(iii) Single-phase induction motor

The motor which converts single-phase AC electric energy into mechanical power by using electromagnetic induction is known as a single-phase induction motor.

(iv) Three-phase Induction Motor

The motor which converts 3-phase AC electric energy into mechanical power is known as a three-phase induction motor.

3. Linear Motor

A linear motor is an electric motor that has had its unrolled stator and rotor. It produces a linear force along its length instead of the rotational torque (force). Mostly Linear motors are used on sliding doors and in actuators.

Types of DC Motor

As per the chart, based on its construction and electrical connection, the DC motor has different types.

1. Separately Excited DC Motor

In this motor, the DC windings are excited by the separate DC source. The separate DC source energizes the armature windings of the motor due to this, it produces the flux.

2. Permanent Magnet DC Motor

The motor which uses a permanent magnet to create field flux is a permanent magnet DC motor (PMDC). 

The PMDC motor provides more starting torque and has very good speed regulation. But it has a limitation of torque so they are typically found on low horsepower applications such as automobile starters, wipers, air conditioners, etc.

3. Self-Excited DC Motor

The motors in which the field winding is connected either in series or parallel to the armature winding is known as self-excited DC motor. Based on this, the self-excited DC motor is classified as:

(i) Series Wound DC motor

In the series wound DC motor, the field winding connects in series with the armature of the motor.

(ii) Shunt Wound DC motor

In the shunt wound DC motor, the field winding connects in parallel with the armature of the motor.

The shunt-wound motor offers good speed regulation. In this motor, the field winding can be separately excited or connected to the same source as the armature.

(iii) Compound Wound DC motor

The compound wound rotor has both the parallel and series connection of the field winding. The excitation of a compound wound DC motor has two types depending on the nature of compounding.

Cumulative compound DC motor- In this, the shunt field flux produced by the shunt winding assists the main field flux produced by the series winding.

 Differential Compound DC Motor- In this, the shunt field flux diminishes the effect of the main series winding we can say that the motor

To understand the types of DC motor in details, refer to the article Types of DC Motor.

Other Motors

There are different types of DC or AC motors available in the market with a variety of specification like Stepper motor, servo motor, brushed DC motor, brushless DC motor etc.

# Stepper Motor

Stepper motors are also DC motors that divide a full rotation into a number of equal steps. They have multiple coils and all are organized in groups called "phases". 

This motor will rotate one step at a time by energizing each phase in sequence.  Since each pulse helps the motor to rotate at a precise angle like1.8°.

The motor position can be controlled without any feedback system. This motor provides very precise positioning and speed control. For this reason, stepper motors are used in many precision motion control applications. Stepper motors come in different sizes and electrical characteristics.

# Servo Motor

A servo motor is a simple electric motor that rotates the machine parts with high efficiency and great precision. The servo motors are available in both AC and DC.

A servomotor is a linear or rotary actuator that allows for precise control of linear or angular position, velocity and acceleration.

The Servo Motor uses a regular motor and coupled with a sensor for positional feedback. It also requires a relatively sophisticated controller to operate.

Servo motors are used in many applications like toy car, RC helicopters and planes, Robotics, etc. To know more about it, refer to the article what is a servo motor?

Final Words

I hope this article helps you to understand the detailed information about the Types of Electric motor. These motors are used in number of applications. We at Robu.in hope that you found it interesting and that you will come back for more of our educational blogs.

Tags : AC motor , DC motor , electric motor , motor , types of AC motor , types of DC motor