Synchronous Motor vs. Induction Motor

At their core, electric motors are devices that convert electrical energy into mechanical motion, powering everything application. In the realm of electrical machinery, two prominent contenders stand out – the synchronous motor vs. induction motor.

These two distinct types of electric motors serve as essential workhorses in a myriad of industrial and commercial applications, each possessing unique characteristics and operational principles.

In this blog, we’ll explore how alternating current (AC) electric motors work and the synchronous and induction motors’ differences, advantages, and applications.

How Does an AC Electric Motor Work?

AC motors, short for alternating current motors, are the backbone of electrical systems and industrial applications. These motors can convert electrical energy into mechanical motion by utilizing the alternating current supplied by the power grid.

AC motors operate on the fundamental principle of electromagnetic induction, which was first described by Michael Faraday. In essence, as the direction of the alternating current reverses in the coils of the motor, it creates a changing magnetic field. This magnetic field interacts with the rotor or armature of the motor, causing it to rotate.

AC motors come in various types, including synchronous and induction motors, each with its unique characteristics and applications. They have their efficiency, reliability, and adaptability, making them indispensable in powering an array of devices, from household fans and air conditioners to industrial pumps and conveyor systems.

ac motor

Synchronous Motors

What Are Synchronous Motors?

Synchronous motors are a category of electric motors that can operate at a constant speed precisely synchronized with the supply frequency. They are capable of rotating at a synchronous speed, which is determined by the frequency of the alternating current (AC) power supply and the number of poles in the motor.

Unlike induction motors, synchronous motors do not operate at less than the synchronous speed of the motor. In fact, they can maintain this synchronous speed under various load conditions, which makes them ideal for applications that require precise speed control.

Advantages of Synchronous Motor

The advantages of synchronous motors lie in their precision. They are capable of maintaining constant speed, making them ideal for applications where timing is critical. These motors excel in scenarios where a fixed speed or synchronous operation is essential.

Applications of Synchronous Motors

Synchronous motors find their niche in various sectors, including timekeeping, robotics, and precision control systems. They drive applications where maintaining a precise speed is imperative, such as in clocks, timers, and other time-sensitive devices.

Induction Motors

What Are Induction Motors?

Induction motors, also known as asynchronous motors, are a class of electric motors that have simplicity and reliability. These motors operate on the principle of electromagnetic induction, which supplies alternating current (AC) power to the stator windings, creating a rotating magnetic field. This rotating field induces currents in the rotor(squirrel cage rotor or wound rotor), setting it in motion. 

Induction motors are characterized by their lack of a direct electrical connection to the rotor, making them robust and low-maintenance. They are suitable for various applications, from household appliances to industrial machinery, owing to their adaptability, efficiency, and cost-effectiveness.

Advantages of Induction Motors

Induction motors are favored for their robust and straightforward design. They require minimal maintenance, and their reliability is second to none. These motors are known for their ability to deliver consistent performance in various settings.

Applications of Induction Motors

The versatility of induction motors is remarkable. They can be found in household appliances, industrial machinery, conveyor systems, and even electric cars. Their reliability and adaptability make them the motor of choice in a wide range of applications.

Synchronous Motor vs. Induction Motor

synchronous motor vs. induction motor

Understanding the distinctions between these two motor types is crucial for making informed choices in selecting the right motor for a specific application. This part highlights the key differences between synchronous and induction motors.

Synchronization with Supply Frequency:

Synchronous Motors: Operate at a constant speed and voltage precisely synchronized with the supply frequency.

Induction Motors: Operate at a speed lower than the synchronous speed and are not synchronized with the supply frequency.

Starting Mechanism:

Synchronous Motors: It is not self starting. It has to be run up to synchronous speed by any means before it can be synchronized to AC supply.

Induction Motors: These have self-starting torque and do not require external equipment to start. It can start when they supply power to the stator, eliminating the need for a power source to excite or start the rotor.

Precision and Speed Control:

Synchronous Motors: Excel in applications that demand precise speed control and synchronous operation, such as timekeeping devices and precision robotics.

Induction Motors: Offer reliable performance but do not provide the same level of speed control as synchronous motors. If the load increases the speed of the induction motor decreases.


Synchronous Motors: Tend to have slightly higher efficiency due to their ability to operate at a precise speed, but the difference may not be significant in many applications.

Induction Motors: Are known for their overall energy efficiency.


Synchronous Motors: Often require more maintenance due to their complex design, which may include excitation systems and slip rings or brushes.

Induction Motors: Are renowned for their simplicity and low maintenance requirements, as they have fewer moving parts and no slip rings or brushes.

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In the world of AC motors, the choice between synchronous and induction motors is not a matter of one being superior to the other. Each motor type has its strengths and applications where it excels. Making an informed decision requires a thorough understanding of the specific requirements of your application.

The precision and synchronization of synchronous motors have their place, just as the reliability and versatility of induction motors have theirs. The key lies in recognizing the unique demands of your application and selecting the motor that aligns best with those needs.


What factors should be considered when choosing between synchronous vs. induction motors?

The differences between Synchronous and Asynchronous Motor are explained by considering factors like their type, slip, requirement of additional power source, the requirement of slip ring and brushes, cost, efficiency, power factor, current supply, speed, self starting, effect in torque because of change in voltage, their operational speed and various applications of both Synchronous and Asynchronous motor.

The nature of the application and the desired performance characteristics play a pivotal role in motor selection.

Can induction motors offer variable speed control?

Induction motors can provide variable speed control through the use of external devices like variable frequency drives (VFDs).

Do both synchronous and induction motors require maintenance, and how do they compare in this regard

Both synchronous and induction motors require maintenance, but the extent and nature of maintenance differ. Synchronous motors generally demand more maintenance due to their complex design, which includes excitation systems and slip rings or brushes. These components may require periodic inspection and replacement.

In contrast, induction motors are known for their robust and low-maintenance design. They have fewer moving parts, no slip rings, and no brushes. This simplicity reduces the need for frequent maintenance, making them a preferred choice in applications where reliability and minimal upkeep are essential, contributing to lower operational costs and increased uptime.

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